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Crystal engineering of metal-carboxylate based coordination polymers

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Title:
Crystal engineering of metal-carboxylate based coordination polymers
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Book
Language:
English
Creator:
Lu, Jianjiang
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University of South Florida
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Tampa, Fla.
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Subjects / Keywords:
Self-assembly
Supramolecular chemistry
Metal-organic supramolecular synthons
Topology
Nanoscaled secondary building units
Dissertations, Academic -- Chemistry -- Doctoral -- USF   ( lcsh )
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government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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Summary:
ABSTRACT: This dissertation endeavors to delineate practical paradigms for crystal engineering based upon the understanding of supramolecular chemistry and self-assembly, i.e. the design and synthesis of novel functional crystalline materials. Two basic metal-organic building units, Zn(RCO₂)₂(py)₂ and (L₂)M₂(RCO₂)₄ (M = Zn, Cu), as well as nano-scaled secondary building units (nSBUs) that are constructed from Cu₂(RCO₂)₄ are researched and discussed. Design strategies have been developed to propagate these metal-organic synthons into predictable coordination polymer networks. A series of crystal structures, as well as their syntheses and characterization, are presented. This work demonstrates that supramolecular structures can be designed from pre-selected molecular precursors with the consideration of chemical functionalities and geometrical arrangements.The design strategy represents a practical paradigm for the construction of porous materials as well as interesting networks with special topologies. The modular nature of these metal-organic building units introduces a broad impact on the discovery of novel coordination compounds with potential useful properties.
Thesis:
Dissertation (Ph.D.)--University of South Florida, 2004.
Bibliography:
Includes bibliographical references.
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Mode of access: World Wide Web.
Statement of Responsibility:
by Jianjiang Lu.
General Note:
Includes vita.
General Note:
Title from PDF of title page.
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Document formatted into pages; contains 239 pages.

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oclc - 56137546
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ABSTRACT: This dissertation endeavors to delineate practical paradigms for crystal engineering based upon the understanding of supramolecular chemistry and self-assembly, i.e. the design and synthesis of novel functional crystalline materials. Two basic metal-organic building units, Zn(RCO)(py) and (L)M(RCO) (M = Zn, Cu), as well as nano-scaled secondary building units (nSBUs) that are constructed from Cu(RCO) are researched and discussed. Design strategies have been developed to propagate these metal-organic synthons into predictable coordination polymer networks. A series of crystal structures, as well as their syntheses and characterization, are presented. This work demonstrates that supramolecular structures can be designed from pre-selected molecular precursors with the consideration of chemical functionalities and geometrical arrangements.The design strategy represents a practical paradigm for the construction of porous materials as well as interesting networks with special topologies. The modular nature of these metal-organic building units introduces a broad impact on the discovery of novel coordination compounds with potential useful properties.
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Crystal Engineering of Metal-Carbo xylate Based Coordination Polymers by Jianjiang Lu A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry College of Arts and Sciences University of South Florida Major Professor: Michael J. Zaworotko, Ph.D. Kyung Woon Jung, Ph.D. Li-june Ming, Ph.D. Julie P. Harmon, Ph.D. Wenbin Lin, Ph.D. Date of Approval: April 29, 2004 Keywords: Self-Assembly, Supramolecular Ch emistry, Metal-Organic Supramolecular Synthons, Topology, NanoScaled Secondary Building Units Copyright 2004 Jianjiang Lu

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A A c c k k n n o o w w l l e e d d g g e e m m e e n n t t s s First and foremost, I would like to expr ess my deepest thanks and the most sincere appreciation to my supervisor, Prof essor Michael Zaworotko, for his advice and guidance throughout my whole study. I would like to thank my committee members, Dr. Julie Harmon, Dr. Kyung Woon Jung, Dr. Li-june Ming and Dr. Wenbin Li n, for their encouragement and guidance. I would also like to express my sincere gratitude to all of the members of the Zaworotko research group, who have helped me in one way or another. Specifically, I would like to thank Dr. Brian Mouton, who ha s made significant contributions to the research described herein. In addition, I woul d like to acknowledge the Staff and Faculty of the Department of Chemistry at the Univ ersity of South Florid a for their support and encouragement. Finally, I am very grateful to my wife (Hong Xiang) fo r her love, concern, understanding and moral support.

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Many of the figures in this dissertation are presented in colo r. If you are looking at a black & white copy and need to view the co lor images for clarificat ion, the original is available through the library at the University of South Florida, at www.virtual.lib.usf.edu.

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i T T a a b b l l e e o o f f C C o o n n t t e e n n t t List of Tables viii List of Figures x Chapter 1 Introduction 1 1.1. Preamble 1 1.2. Crystal Engineering 2 1.2.1. Background 2 1.2.2. Modular chemistry 5 1.2.3. Crystal engineering and supram olecular chemistry in solution 5 1.3. Coordination Polymers and Design Strategies 7 1.3.1. Background 7 1.3.2. Design principles 8 1.3.2.1. Design of porous materials 12 1.3.2.2. Design of crystals in non-center symmetry from achiral ligands 13 1.3.3. Supramolecular isomerism in coordination polymers 15 1.3.4. Supramolecular synthons in crystal e ngineering of coordination polymers 15 1.3.4.1. Mononuclear center mode 17 1.3.4.2. Secondary Building Units (SBUs) 18 1.3.5. Examples of coordination polymer s from supramolecular synthons 20 1.3.5.1. Zero dimensional structures 20

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ii 1.3.5.2. Infinite structures 24 1.4. Summary 28 Chapter 2 Coordination Polymers Based upon Zn(RCO2)2(py)2 29 2.1. Preamble 29 2.2. Compound 1 ---Zn(bdc)(py)2 31 2.2.1. Experimental Section 31 2.2.2. Structural Elucidation 33 2.3. Compound 2 -Zn1.5(btc)(py)3•1.5H2O 35 2.3.1. Experimental Section 35 2.3.2. Structural Elucidation 35 2.3.3. Network topology 37 2.4. Compound 3 -[Zn(bdc)(bpeta)]n. x (guest) (3a-3e) 39 2.4.1. Experimental Section 39 2.4.2. Structural Elucidation 40 2.5. Compound 4 -[Zn(bdc)(bpeta)]n x (small guest) (4a and 4b) 45 2.5.1. Experimental Section 45 2.5.2. Structural Elucidation 46 2.6. Discussion and Conclusions 48 2.7. CSD Database studies of Zn(RCO2)2(N)2 51 Chapter 3 Three Dimensional Structures Based upon Zn2(RCO2)4 and Zn2(RCO2)3 SBUs 53 3.1. Preamble 53 3.2. Compound 5 -{[Zn2(btc)]8[Zn2(btc)1.333]3}n 55

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iii 3.2.1. Experimental Section 55 3.2.2. Structure Elucidation 55 3.2.3. Network Topology 57 3.3. Compound 6 – [L2Zn2(btc)4/3]n 64 3.3.1. Experimental Section 64 3.3.2. Structure Elucidation 64 3.3.3. Network Topology 66 3.4. Discussion 68 Chapter 4 Self-Assembled Supramolecules Based upon Dicopper Tetracarboxylate Complexes, [(Cu2(RCO2)4)] and Angular Ditopic Ar omatic Carboxylate Acids 73 4.1. Preamble 73 4.2. Compound 7 -[(L)(S)Cu2(bdc)2]12 (7a and 7b) 74 4.2.1. Experimental Section 74 4.2.2. Structure Elucidation 75 4.3 Compound 8 -{[Cu2(bdc)2(py)2]4}n 79 4.3.1 Experimental Section 79 4.3.2. Structure Elucidation 79 4.4. Compound 9 -{[Cu2(bdc)2(4-pic)2]4 4(o-Dichlorobenzene)}n 83 4.4.1. Experimental Section 83 4.4.2. Structure Elucidation 84 4.5. Compound 10 -{[Cu2(tdc)2(MeOH)2]44Naphthalene-8MeOH}n 86 4.5.1. Experimental Section 86 4.5.2. Structure Elucidation 87

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iv 4.6. Compound 11 (Kagome Lattice) -{[L2Cu2(bdc)2]3}n (11a and 11b) 89 4.6.1. Experimental Section 89 4.6.2. Structure Elucidation 90 4.7. Compound 12 -[Cu2(bdc)2(L)2]n (USF-1) 95 4.7.1. Experimental Section 95 4.7.2. Structure Elucidation 95 4.7.3. Network Topology 97 4.8. Discussion and Conclusion 98 Chapter 5 Self-Assembled Supramolecules Based upon Linear Dimetal Tetracarboxylate Complexes, [(M2(RCO2)4)] 106 5.1. Preamble 106 5.2. Compound 13 -[Cu2(C6H5CO2)4](bpeta)xGuest (13a-13g) 110 5.2.1. Experimental Section 110 5.2.2. Structure Elucidation 112 5.2.3. Discussion 119 5.3. Compound 14 -[HMTA][Cu2(CH3OC6H4CO2)4] 119 5.3.1. Experimental Sections 119 5.3.2. Structure Elucidation 120 5.3.3. Discussion 122 5.4. Compound 15 -[HMTA]2[Cu2(p-NO2PhCO2)4]3 125 5.4.1. Experimental Section 125 5.4.2. Structure Elucidation 126 5.4.3. Discussion 127

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v 5.5. Compound 16 -[HMTA]3[Cu2(C2H5CO2)4]5, the first two-dimensional supramolecular (5, 3 4)-net 129 5.5.1. Experimental Section 129 5.5.2. Structure Elucidation 130 5.5.3. Discussion 132 5.6. Compound 17 -[HMTA][Cu2(PhCO2)4]2 134 5.6.1. Experimental Section 134 5.6.2. Structure Elucidation 135 5.6.3. Discussion 137 5.7. Compound 18 – (10,3)-a networks, [Melamine]2[Cu2(C2H5CO2)4]3 and [HMTA]2[Cu2((CH3)3CCO2)4]3 (18a and 18b) 139 5.7.1. Experimental section 139 5.7.2. Structure Elucidation 140 5.7.3. Discussion 145 5.8 Conclusions 147 5.9. CSD database studies of Di metal tetracarboxylate SBUs 149 Chapter 6 Conclusions & Future Directions 154 6.1. Summary 154 6.2. Crystal Engineering vs Design 155 6.3. Future direction 157 6.3.1. A new interpretation of the network topology of compound 6 157 6.3.2. Partially terminated square SBUs 160 6.4. Some pre-designed structures 161

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vi 6.5. The last words 163 References 164 Appendices 181 Appendix A1. Crystal data and structure refinement for compound 1 182 Appendix A2. Crystal data and structure refinement for compound 2 183 Appendix A3. Crystal data and structure refinement for compound 3a 184 Appendix A4. Crystal data and structure refinement for compound 3b 185 Appendix A5. Crystal data and structure refinement for compound 3c 186 Appendix A6. Crystal data and structure refinement for compound 3d 187 Appendix A7. Crystal data and structure refinement for compound 3e 188 Appendix A8. Crystal data and structure refinement for compound 4a 189 Appendix A9. Crystal data and structure refinement for compound 4b 190 Appendix A10. Crystal data and stru cture refinement for compound 5 191 Appendix A11. Crystal data and stru cture refinement for compound 6 192 Appendix A12. Crystal data and stru cture refinement for compound 7a 193 Appendix A13. Crystal data and stru cture refinement for compound 7b 194 Appendix A14. Crystal data and stru cture refinement for compound 8 195 Appendix A15. Crystal data and stru cture refinement for compound 9 196 Appendix A16. Crystal data and stru cture refinement for compound 10 197 Appendix A17. Crystal data and stru cture refinement for compound 11a 198 Appendix A18. Crystal data and stru cture refinement for compound 11b 199 Appendix A19. Crystal data and stru cture refinement for compound 12 200 Appendix A20. Crystal data and stru cture refinement for compound 13a 201

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vii Appendix A21. Crystal data and stru cture refinement for compound 13b 202 Appendix A22. Crystal data and stru cture refinement for compound 13c 203 Appendix A23. Crystal data and stru cture refinement for compound 13d 204 Appendix A24. Crystal data and stru cture refinement for compound 13e 205 Appendix A25. Crystal data and stru cture refinement for compound 13f 206 Appendix A26. Crystal data and stru cture refinement for compound 13g 207 Appendix A27. Crystal data and stru cture refinement for compound 14 208 Appendix A28. Crystal data and stru cture refinement for compound 15 209 Appendix A29. Crystal data and stru cture refinement for compound 16 210 Appendix A30. Crystal data and stru cture refinement for compound 17 211 Appendix A31. Crystal data and stru cture refinement for compound 18a 212 Appendix A32. Crystal data and stru cture refinement for compound 18b 213 Appendix B 14 types of pe ntagon periodical tilting 214 About the Author End Page

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viii L L i i s s t t o o f f T T a a b b l l e e s s Table 2.1. Selected crystallographic parameters for 1 32 Table 2.2. Selected crystallographic parameters for 2 35 Table 2.3. Selected crystallographic parameters for 3a-e 40 Table 2.4. Selected crystallographi c parameters for 4a and 4b 45 Table 2.5. Zinc tetrahedral with two nitrogen atoms and two carboxylates 52 Table 3.1. Selected crystallographic parameters for 5 55 Table 3.2. Selected crystallographic parameters for 6 64 Table 4.1. Selected crystallographi c parameters for 7a and 7b 75 Table 4.2. Selected crystallographic parameters for 8 79 Table 4.3. Selected crystallographic parameters for 9 84 Table 4.4. Selected crystallographic parameters for 10 87 Table 4.5. Selected crystallographi c parameters for 11a and 11b 90 Table 4.6. Selected crystallographic parameters for 12 95 Table 5.1. Selected crystallographic parameters for 13a-g 111 Table 5.2. TGA data summary of the per centage and temperature upon removal of guest molecules in compounds 13b-13g 112 Table 5.3. Selected crystallographic parameters for 14 120 Table 5.4. Selected crystallographic parameters for 15 126 Table 5.5. Selected crystallographic parameters for 16 130 Table 5.6. Selected crystallographic parameters for 17 135

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ix Table 5.7: Selected crystallogr aphic parameters for 18a and 18b 140 Table 5.8. Number of reported SBU struct ures for the transition elements 149 Table 5.9. Copper SBU with nitrogen donor liga nds at axial direc tions (188 hits) 150 Table 5.10. Copper SBU with oxygen donor ligands at axial directions (229 hits) 152 Table 5.11. Copper SBU with nitrogen atom s at axial directions (this work) 153

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x L L i i s s t t o o f f F F i i g g u u r r e e s s Figure 1.1. Crystal engineering – from molecule to crystals 6 Figure 1.2. Some examples of high symme try multidentate organic ligands 10 Figure 1.3. Examples of coordinatio n polymer network topologies 12 Figure 1.4. Some examples of or ganic supramolecular synthons 16 Figure 1.5. Examples of mono-metal organi c (pyridine or carboxylates or both) recognition styles (synthons) 17 Figure 1.6. Some examples of metalcarboxylate Secondary Building Units (synthons) 19 Figure 1.7. Dimetaltetracarboxyl ate, two different ways to build extended structures 20 Figure 1.8. Formation of an M4L4 molecular square 21 Figure 1.9. The 5 Platonic and 13 Archimedean Solids 22 Figure 1.10. Fifty molecules assemble to form a supramolecular dodecahedron. 22 Figure 1.11. Formation of an M6L4 octahedral cage 23 Figure 1.12. Formation of an M4L6 Molecular tetrahedral 23 Figure 1.13. Formation of (4,4) square grid by metal ions and 4,4’bipyridine in 1:2 ratio 25 Figure 1.14. Formation of octahe dral 3-D open-framework 25 Figure 1.15. Formation of (4,4) square grid by square SBU and 1,4-BDC 26

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xi Figure 1.16. Formation of cubic 3-D openframework by octahedral SBU and 1,4BDC 26 Figure 1.17. Formation of dimondi od 3-D chiral networks 27 Figure 1.18. Formation of (6,3) 2-D chiral open-framework 27 Figure 2.1. Zn(CH3CO2)2(py)2, CSD #ZZZPKM01, an example of metal organic supramolecular synthon 30 Figure 2.2. Racemic chain dimmer (a ) and their packing view along bc plane (b) and in a axial direction (c) in compound 1 34 Figure 2.3. Overhead (a) and perspective (b ) views of the two dimensional network seen in the crystal structure of Zn1.5(btc)(py)3, 2. 37 Figure 2.4. Schematic representation of zinc and trimesate nodes 38 Figure 2.5. Schematic illustration of Zn1.5(btc)(py)3, 2. 39 Figure 2.6. Space-filling of perspective (a ) and side view (b) of the puckered rectangular grid coordinati on polymer network in 3a 42 Figure 2.7. An illustration of (a) packing view of the puckered grid and (b) how two noncovalent networks (illustrated in space-filling mode) generate parallel interpenetration with one puc kered rectangular grid (ill ustrated in stick mode) in 3a. 43 Figure 2.8. A view of the noncovalent nets that are formed by benzene molecules in 3a 44 Figure 2.9. Schematic illustration of puckered grid, [Zn(bdc)(bpeta)]n, 3. 44 Figure 2.10. (a) a (6,3) network built from Zn/bdc zigzag chain and bpeta, (b) the cross linking of (6,3) network by another bpeta 47

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xii Figure 2.11. The pseudo-diamondoid network in 4a. The bridging ligands are replaced with straight lines that connect zinc nodes. 47 Figure 2.12. An illustration of the thr ee pseudo-diamondoid networks that interpenetrate in 4a 48 Figure 3.1. SBU based upon M2(carboxylate)4 – a supramolecular synthons with a square molecular shape 54 Figure 3.2. Molecular and Space f illing models of compound 5, {[Zn2(btc)]8[Zn2(btc)1.333]3}n 57 Figure 3.3. Schematic representation of dizinc SBU and trimesate 58 Figure 3.4. Schematic representation of ( 3,4)-connected net of compound 5 after first simplification 59 Figure 3.5. Schematic representation of compound 5 with squa re and triangle 60 Figure 3.6. (a)The secondary building units (SBUs) employed for the construction of faceted polyhedra; (b) crystal struct ure and schematic illustration of 5 view along the [001] crystallographic plane. 61 Figure 3.7. Small cubicuboctahedra and oc tahemioctahedron extracted from 5 63 Figure 3.8. Molecular and Space fill ing models of compound 6, [Zn2(btc)1.333]n 65 Figure 3.9. Schematic representation of ( 3,4)-connected net of compound 5 after first simplification 66 Figure 3.10. Schematic representation of compound 6 with square 67 Figure 3.11. Crystal structure and schema tic illustration of 6 viewed along the [001] crystallographic plane 67 Figure 3.12. Small rhombihexahedron extracted from 6 68

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xiii Figure 3.13. An illustration of how the vertices of the molecular squares and triangles connected by the btc moieties 70 Figure 3.14. Schematic illustration of th e nine possible faceted polyhedra 72 Figure 4.1. Molecular, space fill ing models and topology of small rhombihexahedra in compound 7 76 Figure 4.2. Body-center cubic packing of small rhombihexahedra in 7a (a) and 7b (b) 77 Figure 4.3. Schematic illustration of Compound 7 of SBU connectivity 78 Figure 4.4. Two different arrangements of bdc molecules around the dicopper center in (a) Compound 7 and (b) compound 8 80 Figure 4.5. Space filling and ball and stick m odels of two different types of nanosized SBUs in Compound 8 81 Figure 4.6. (a) Space-filling diag ram of the crystal structur e of 8. (Guest molecules have been omitted for clarity). (b) Prof ile of the hour-glass shaped channels between adjacent bowls. The shaded area is the empty volume; guest molecules are located in the widest areas of the channels. (c)Packing view of the layers 82 Figure 4.7. Schematic illustration of the network observed in compound 8 (a) top view (axial pyridines are omitted for cl arity) (b) side view (molecules are omitted). 83 Figure 4.8. Space filling and ball and stick models of 1,2 alternative nano-sized SBU in Compound 9 85

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xiv Figure 4.9. (a) Space filling model of one laye r structure (b) One layer in ball-stick model with odichlorobenzene solvents in space-filling model. Each cavity contains one guest molecule. Note: guests are in polar arrangement 85 Figure 4.10 Packing view of compound 9 (4-picoline and guest molecules are omitted for clarity) 86 Figure 4.11. Space filling and ball and stick models of 1,2 alternative nano-sized SBU in Compound 10 88 Figure 4.12. (a) Ball and stick diagram of the layer structure of 10. Each cavity contains one naphthalene and two MeOH guest molecules. (b) Packing view of the stacking of layers in 10 88 Figure 4.13. Space filling and ball-stick mode ls of trigonal nSBU in Compound 11 91 Figure 4.14. (a) Space-filling diagram of the crystal structure of 11. (Guest molecules have been omitted for clarity). (b) Packing view of the stacking of layers in 11a 92 Figure 4.15. Packing view of the stacking of layers in 11b 93 Figure 4.16. Schematic illustration of th e network observed in compound 11 (a) top view (axial pyridines are omitted for clarity) (b) side view (molecules are omitted). 94 Figure 4.17. (a) Crystal structure of 12; (b) bdc molecule nearly at the same plane in compounds 7, 8, and 11; (c) Carboxylat e groups in bdc molecule deviate themselves from benzene ring in compound 12 96 Figure 4.18. Schematic illustration of the topology of USF-1 and CdSO4 97

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xv Figure 4.19. Five structures with different topologies that ar e constructed from square SBU and bdc 98 Figure 4.20. Connectivity of SBUs in compound 7 and compound A 100 Figure 4.21. Two different arra ngements of molecular squares bridged by bdc (a) in compound 7; (b) in compounds 8, 9 and 11 101 Figure 4.22. Schematic illustration of the permutation of two carboxylate groups in dicarboxylic acid 102 Figure 4.23. Schematic illustration of four atropisomers of a calix[4]arene: (a) cone, (b) partial cone, (c) 1,2-alte rnate, and (d) 1,3-alternate. 103 Figure 4.24. Illustration of extraction of 2D networks (without axial ligands) in compounds 8 and 11 from the 3-D network of compound 6 104 Figure 5.1. The M2( -O2CR)4 moiety functions as linear spacer. This moiety has been prepared for a wide range of transition metals and can be readily functionalized at either the equatorial or axial positions. 107 Figure 5.2. Organic ligands that are used to connect linear SBUs 108 Figure 5.3. HMTA molecular can be proj ected as a tetrahedral node, angler, pseudo trigonal or tetragonal geometries will be generated when HMTA uses its 2, 3, or 4 nitrogen atoms respectively. 108 Figure 5.4. A schematic representation of the possible topologies that are based upon the symmetry of the ligands used in this study. 109 Figure 5.5. (a) A view of the 1-D chain co mposed of bimetal liner spacer and bipyethane; (b) Tope view of the chain (c ) Packing view of ch ains into a layer structure by interdigitation and C-H interactions; (d) Tope view of the

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xvi layer (the channel direction is marked by a blue arrow) (e) A view of two adjacent layers stack each other by interactions. 114 Figure 5.6. Type I host/guest compounds, 13b. (a) Anisole is located inside the channel and methoxyl group is heading to the space created by rotation of bpeta. (b) A view of the packing style. 116 Figure 5.7. Type II compound 13e (a) pack ing view; (b) solvent chain running through the channel; (c) side vi ew of the solvent chain. 117 Figure 5.8. Type III host/guest compound, 13g, benzene molecules are the aromatic solvent sitting between the laye rs with the alternative style of 1:1 and 1:2. 118 Figure 5.9. (a) View of chain structure and (b) View of packing style of [HMTA][Cu2(p-CH3OC6H4CO2)4] 14. 121 Figure 5.10. Eight topologically different modes of 1-D coordination polymers 123 Figure 5.11. Two other possible topologies from angular node and linear spacer: square box (a) and 1-D helix (b) 125 Figure 5.12. Overhead and perspective views of the Honeycomb network (Nitrophneyl groups and H atoms omitted for clarity) seen in the crystal structure of [HMTA]2[Cu2(p NO2C6H4CO2)4]3, 15. 127 Figure 5.13. a pseudo trigonal node generated by HMTA 128 Figure 5.14. Honeycomb structure from copper acetate and tpt 129 Figure 5.15. Overhead and pers pective views of the (5,3 4)-network The ethyl groups (omitted for clarity) fill the pe ntagonal cavities, which have sides of 1.00 nm and diagonals of 1.54 nm. 131

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xvii Figure 5.16. There nets of 14 tilings th at contain congruent pentagons. 133 Figure 5.17. A tetrahedral node projected down the 3-fold axis (a), and 2-fold axis (b) affording pseudo trigonal and pseudo square geometries, respectively. 134 Figure 5.18. Diamondoid networks using lin ear SBU’s and HMTA tetrahedral nodes. (Phenyl groups were omitted for clarity) 136 Figure 5.19. A perspective view of [Mo2(MeCO2)40.5HMTA 0.5CH2Cl2], a double interpenetrated diamondoid network 138 Figure 5.20. Environment of a melamine mo lecule coordinated to three copper SBU (R groups in SBU were omitted for clarity) affording trigonal node. 141 Figure 5.21. (a). A view down the c axis il lustrateing the four interpenetrating networks of [Melamine]2[Cu2(C2H5CO2)4]3 18a; (b). A single net of (10,3)-a network which is left handed along the c axis; (c). A view along the 3-fold axis of the same single net; (d). A view of the 41 helix from part of one independent net (carboxylate groups were omitted for clarity in a-c). 142 Figure 5.22. (a). One (10,3) circle consis ts of 10 HMTA molecules as nodes and 10 copper square SBUs function as linear spacers; (b). A single left-hand net of the (10,3)-a network in 18b (Carboxylate groups were omitted for clarity and HMTA was replaced by tetradedral node) 144 Figure 5.23. The (10,3)-a network of [HMTA]2[Cu2((CH3)3CCO2)4]3 18b. (a). View along the pseudo41 axis of one single ne t; (b). View along the pseudo 3-fold axis of one single net; (c). Ra cemic interpenetration of two (10,3)-a nets. (Carboxylate groups were omitted for clarity) 144

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xviii Figure 5.24. (10,3)-a network (right hand) pr ojection along 4-fold axis and 3-fold axis 145 Figure 5.25. Histogram showi ng the distribution of Cu-O distances among the structures containing the SBU in c oordination with two N-donor and four carboxylates 151 Figure 5.26. Histogram showi ng the distribution of Cu-N distances among the structures containing the SBU in c oordination with two N-donor and four carboxylates 151 Figure 5.27. Histogram showi ng the distribution of Cu -Cu distances among the structures containing the SBU in c oordination with two N-donor and four carboxylates 152 Figure 6.1. Schematic representation of compound 6 with triangle 158 Figure 6.2. Octahedral/cuboctahedra buildi ng units that are extracted from compound 6 159 Figure 6.3. Four possible cases of the partially terminated square SBU 161 Figure 6.4. Six pre-designed stru ctures based upon the partially terminated square SBU 162 Figure 6.5. Two examples of possible stru ctures that can be built from linear spacer and angular ditopic amines 162

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xix Crystal Engineering of Metal-Carbo xylate Based Coordination Polymers Jianjiang Lu A A B B S S T T R R A A C C T T This dissertation endeavor s to delineate practical paradigms for crystal engineering based upon the understanding of supramolecular chemistry and selfassembly, i.e. the design and synthesis of novel functional crystalline materials. Two basic metal-organic building units, Zn(RCO2)2(py)2 and (L2)M2(RCO2)4 (M = Zn, Cu), as well as nano-scaled secondary building units (nSBUs) that are constructed from Cu2(RCO2)4 are researched and discussed. Design strategies have been developed to propagate these metal-organic synthons into predictable coordination polymer networks. A series of crystal structures, as well as their syntheses and characterization, are presented. This work demonstrates that supramolecu lar structures can be designed from preselected molecular precursors with the cons ideration of chemical functionalities and geometrical arrangements. The design strate gy represents a practical paradigm for the construction of porous materials as well as in teresting networks with special topologies. The modular nature of these metal-organic building units introduces a broad impact on the discovery of novel coordination compounds with potential useful properties.

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1 C C h h a a p p t t e e r r 1 1 I I n n t t r r o o d d u u c c t t i i o o n n 1.1. Preamble Crystals are defined as “solids that ha ve, in all three dimensions, a regularly repeating internal ar rangement of atoms”.1 One of the most importa nt aspects of crystals is their ability to diffract X-rays since at om distances, bond distances between atoms in crystals, are at the same range of X-ray wa velengths. After the full establishment of Xray crystallography, single cr ystal X-ray diffraction tec hniques have become the preferred method to determine molecular stru ctures. This method is now becoming more and more powerful mainly due to the c ontinuous advance of computer technology in crystal data collection, crystal structure solving and view ing, as well as the construction of crystal structure database. We are actually living in a world of cr ystals. Sugar, ice, salt, diamond and gold are very well known examples of crystalline solids. Crystallin e material stands out as a distinct substance mainly due to the increa sing significance of crystalline material in science and technology as well as in everyday life. Research in this particular field is largely motivated by searching for a better unde rstanding of the physical principles that govern the crystal packing as well as fo r novel functional crystalline materials.

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2 1.2. Crystal Engineering 1.2.1. Background Crystal engineering, a concep t that is defined as “ making crystals by design ”, was traditionally regarded as being introduced by Schmidt in 1971.2 However, recent literature surveys illustrate that it was actually first introduced by Pepinsky in 1955.3 The initial purpose of this concept is very limited. Schmidt called engineering crystal structures for solid-state photochemistry, while Pepinsky wanted to design crystal structures from big ion comp lexes. However, during the last two decades, this new concept has spread into such dive rse areas as material chemistry,4-6 pharmacy,7-13 nanotechnology14-17 and other fields.18-30 The property of a crystal depends on two aspects based upon structure-function relationship: 1) its molecular component(s) and 2) the packing style (three-dimensional arra ngement) of molecular component(s). The manipulation of molecular component s is still in the realm of organic synthetic chemistry. During the last century, we have witn essed tremendous progress in molecular chemistry (i.e. putting the atoms toge ther by covalent bond). It used to be the major thought that changing the substances’ structure subsequen tly affected their properties. However, this kind of research ha s reached its limitation due to the fact that big molecules31,32 (e.g. molecular weight larger than 1000 Dalton) will be very difficult and inefficient to be built by the current synthetic method (i.e. adding one or several bonds per step).

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3 It is, however, the second aspect that fl ourishes the idea of crystal engineering and provides an alternative method to the first one. This aspect clearly demonstrates the fact that new functional solid-state materials ar e able to be designed based solely on the existing molecular compounds by putting th em together in a rational way. As the crystal engineering of new crystal line materials is critically dependent on the understanding of intermolecula r interactions, a more detail ed and accurate definition was given by Desiraju:33 “Crystal Engineering ---the understanding of intermolecular interactions in the context of crystal packing and in the utilization of such understanding in the design of new solids with desirable physical and chemical properties.” Desiraju’s definition of the concept of crystal engineering clearly illustrates that controlling molecular components in the solid state in a pred ictable way is critical for controlling the function of crysta lline materials. However, pr ediction of crystal structure from its chemical compositions has been though t a difficult task and has been regarded as “one of the scandals in the physical sciences”.34 Recent advances in the prediction of crystal packing properties and hence the crystal st ructures from molecular component(s) by theoretical modeling have proceede d with only a limited amount of success.33,35-37 On the other hand, synthetic chemistry can be self-dependent. Synthetic chemists can learn from past experiences and summarize them into a system that gives them a guide for future experiments. In the past de cade, crystal engineers have been actively involved in this area of research and tr emendous achievements have been accomplished. As a result, a crystal structure database Cambridge Structural Database (CSD),38 is now playing a more and more important role in crystal engin eering research.

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4 Another important concept, supramolecu lar chemistry, was introduced about the same time as the concept of crystal engineering. Supramolecu lar chemistry is defined as ‘chemistry beyond the molecule’ by Lehn,39 bearing the organized entities of higher complexity that result from the association of two or more chemical species held together by intermolecular forces. The fundamental precept of crystal engineeri ng is that crystals are in effect “supermolecules”,40 the result of a series of directional, and therefore predictable, supramolecular molecular rec ognition events. Under these circumstances, crystal engineering is now a part of s upramolecular chemistry, in other words, “applications of molecular recognition and s upramolecular chemistry to the solid state.”19 The design of new crystalline mate rials is based on the knowledge of intermolecular interactions. These intermolecular interactions include covalent coordination bond, hydrogen bond, hydrophobic/hydrophi lic, polar interaction, etc. Crystals are very complicated systems th at involve numerous weak intermolecular interactions and this is the major reason why it is so difficult for their theoretical study. Considering this situation, it is not surprising that synthetic crystal engineers started their research by choosing relatively strong and di rectional interactions involving coordination and hydrogen bonds. Here, the first step for ch emists to do is to simplify the systems with only a limited number of strong and simple factors, so that other weak effects will be suppressed or ignored. The resulted crystal structures will then be much easier to be controlled and predicted.18

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5 1.2.2. Modular chemistry In one way, building a crystal with molecu les is just the same as building a house with bricks. The molecular building block a pproach -construction of crystals from molecular components -is based upon the a ssumption that molecula r components are the “Legos” and intermolecular in teractions are the “glue”.18,19,31,41-46 This approach gives crystal engineers the idea that judicious selection of molecules with specific shape and functional groups (number, direction and position) are very important si nce this is the key to control the topology of network in a pred ictable way. The modular feature of these building blocks means that they can be fine-t uned to refine the systems to reach the best functional properties. It also hints the structural diversity – the existence of isomerism -since it is possible for a given set of molecular building blocks to generate more than one possible superstructure. Modular approach to crystal engineering is different from theoretical approach in that the degree of control can be only part ial. Although a calibrate d three-dimensional design can give a relatively accurate pr ediction of crystal cell and symmetry,47-49 crystal engineering may just be a control and pr ediction of simple molecular complexes (supermolecules), low dimensional structures su ch as 1-D, 2-D, or distorted 3-D in the resulted crystalline phase. S o, crystal engineering does not have to give a precise prediction on the crystal’s space group and symmetry. 1.2.3. Crystal engineering and supram olecular chemistry in solution Of course, supramolecular chemistry in so lution is very important since biological activities are processed in solution. Supramolecular chemistry in solution is also the most

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6 difficult part of research si nce it involves more complicat ed and dynamic processes. As crystal structures can provide accurate and sometimes unambiguous structural information, crystal engineering can provide de tailed information to help to get a better understanding of supramolecular systems in solution. Nevertheless, there are arguments50 that the phases in liquid do not have to be the same as the phases in solid and molecular behavior may be different in these two states For this reason, it is understandable that in many cases, NMR and mass spectroscopy ar e required for further confirmation. On the other hand, supramolecular chemistry in solution is also very important for crystal engineering in that almost all molecular crystals come from solution. Understanding the nucleation process is th e key to the success of “true” crystal engineering. This process involves competitio ns among all of the possible crystal packing styles. Therefore, the crystal that is finally obtained is actually the “winner” of this contest. To know what is inside this “winne r” is important. However, to understand why it is the “winner” is more important. This is the process that crystal engineers just cannot bypass. Figure 1.1. Crystal engineering – from molecule to crystals Molecular Component(s) Nucleation Process Crystals

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7 1.3. Coordination Polymers and Design Strategies 1.3.1. Background Assigning coordination polymer in the realm of supramolecular chemistry is somehow a controversial issue51 since the coordination bond is mainly a covalent bond while supramolecular chemistry normally d eals with weak noncovalent bond such as hydrogen bond. However, several reasons listed below show that coordination bonding is likely to resulting self-assembly, like hydrogen bonding normally does. 1) Coordination bond is generally weak er than conventional covalent bond,52 2) Coordination bond is normally created without breaking existed covalent bond, 3) Multi-molecular metal/organic buildi ng blocks can be self-assembled spontaneously in ju st one-pot reaction, 4) Coordination bond is more reversible than conventional covalent bond (i.e. self-correct) and it can go back and fort h to reach the most stable phase that the system could have. In summary, coordination polymers are kind of novel infinite supramolecular compounds, formed by self-assembly in which me tal moieties typically act as nodes, and multifunctional organic ligands act as spacers th at propagate these nodes. Both chemical and geometrical attributes of transition metals and organic ligands are the basic elements in coordination polymer chemistry.53 The difference between coordi nation polymers and hydrogen bonded supramolecular structures is the introduction of metal ions/complexes in the formal case.

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8 These metal ions/complexes provide a series of new features into crystal engineering including 1) a set of coordination geometries, 2) a wild range of binding strengths and lability and 3) a variety of photochemical, electro chemical, magnetic and catalytic properties. Coordination polymers are also closely re lated to their inorganic analogue – the minerals, in which they are all crystallin e materials involving metal ions. While the chemistry of minerals deals with interacti ons between inorganic atoms/ions, coordination chemistry deals with the interactions between metal ions and ligands. Minerals have been well studied as part of traditional inorganic chemistry, and crystal engineering of coordination polymers is regarded as part of the modern inorganic chemistry. By applying the concepts of crystal engineering and self-assembly, arti ficial minerals or zeolites54-56 are now feasible by means of the me tal organic supramolecular approach. Many of the topologies of re sulted coordination polymers are unprecedented in nature. 1.3.2. Design principles The design of coordination polymers fr om modular chemistry approach is straightforward. In general, the two comp lementary parts metal ions/complexes and organic ligands constitute the basic building bl ocks. Ditopic functional feature for each of them is required to propagate them selves into superstructures. The coordination nature of metal ions is well recognized. For example, Co(II) and Ni(II) are frequently found to have an octahedral coordination sphere, Cu(I) can adopt a

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9 tetrahedral mode, Pd(II), Pt(II ) are well known to be in a square planar coordination environment. Some metal ions have dive rse coordination modes based upon specific chemical environments, such as Zn(II) or Cu( II). Moreover, metal ions such as Ca(II) and lanthanide(III) compouns have coordination numbe rs larger than six. On the other hand, organic ligands could be linear, trigonal, tetrahedral, or squa re. While exo-dentate multitopic ligands lead the coordination proces s to infinite structures, endo-dentate multitopic ligands have the ability to create fi nite structures. It s hould be noted that the angle of organic molecule multitopic building blocks are not always critically precise in chemistry systems since molecules can bend th emselves and withstand torsion/stress. Some of these organic ligand examples are illustrated in Figure 1.2. The combination of metal ions/complexes and or ganic building blocks into supra-molecular structures will be discussed in the following sections.

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10Figure 1.2. Some examples of high sy mmetry multidentate organic ligands Ditopic Exo-dentate ligands N N O OH N O OH O O H Endo-dentate ligands* N N O OH O O OH Trigonal Exo-dentate ligands N N N N N N O O H O OH O OH Endo-dentate ligands* N OR N N Square N N N N N N N N N N N N Tetrahedra N N N N O O H OH O O H O O H O CN CN CN NC

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11 The metal ions and organic ligands menti oned above are inhere ntly encoded with the information (e.g. function group and symmet ry) to predetermine the potential overall structures of the resulted product. In other words, the ideal situation of these building blocks together with the “rigid” coordina tion bond can provide precisely predictable “ideal networks” based upon mathematics. Although, in the real chemistry world, multidentate ligands may not all fit the ideal situation, these “ideal network” examples still provide “non-ideal” irregu lar networks with the most closed examples and facilitate their study. Basically, there are three different kinds of coordination polymers that can be constructed from nodes (define geometry) and ditopic spacers (linear or angular spacers) that propagate the nodes: 1) metal ions as nodes, organic ligand as spacers, 2) organic ligands as nodes, metal or metal complexes as spacers, and 3) metal ions and organic ligand are all nodes, (in this case, coordination bond and part of the ligand as spacers). About three decades ago, A.F. Wells su mmarized topologies of networks with nodes and spacers from inorganic compounds.57,58 This simplification process results in a change of crystal structures in to a series of points (nodes) of certain geometry that are connected to a fixed number of other points. These topologie s have been used to study the network structures of minera ls. In the earl y 1990’s, Robson59-61 first introduced the same principle into the realm of metal or ganic coordination netw orks. The reduction of supramolecular networks into schematic representations has facilitated the identification and understanding of topologies underlyi ng seemingly complex metal-organic

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12 frameworks. It also provides a useful tool to design new supramolecular coordination polymers based upon building bloc ks and topology blueprints. Figure 1.3 illustrates some examples of coordination polymer networks based upon the node (angular, “T shape”, square, trigon al, tetrahedral, and octahedral node) and spacer (only linear spacer) modes. They are all predictable based on first principle. Figure 1.3. Examples of coordina tion polymer network topologies 1.3.2.1. Design of porous materials20,62 Porous materials are always targeted sin ce they provide the po tential applications in the fields of absorption/desorption, catal ysis, gas-storage, and sensor. Zeolites are prototype compounds. However, zeolites have their own limitations. For example, the pore size cannot be easily expanded into nano scal e, and it is also di fficult to modify the A B E F G H K J I D C L

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13 pore surface and design special features su ch as chirality. However, metal organic coordination polymers can overcome these limitati ons due to the diversity and flexibility of organic compounds. Design of porous materials is straightfo rward. For all the predefined networks, expanding the length of ligands/spacers wi ll increase empty space of channels and cavities and thus create high porosity. The modification of ligands with function groups will provide an opportunity to modify the pore environment. Although interpenetration will frustrate the chance of obtaining large pore materials, it also provides better thermostability and large surface area, which ma y enhance the capability of gas storage. Three-dimensional (3-D) structures are al ways the priority, since low dimensional (1-D or 2-D) structures may overlap each other and diminish the channels. Among all these 3-D structures, diamondiod and octahedral frameworks ar e usually targeted for their convenience to design. Their networks can be bu ilt from tetrahedral or octahedral nodes and linear spacers. Many metal ions or meta l clusters adapt both types of symmetry. 1.3.2.2. Design of crystals in non-center symmetry from achiral ligands Crystals with non-center6,63 symmetry are useful func tion materials that possess special properties such as secondary nonlinear optic (N LO), piezoelectric, and pyroelectric etc. Porous chiral materials also have the potential applications such as chiral separation and asymmetric catalysis. Mainly two methods have been applie d to design these special crystalline materials. One is to use chiral ligands.64-68 This is a method that is getting more and more

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14 attention in recent years. Th e other is to use achiral ligands. There are several design strategies in this method.69 1) Selection of non-center symmetric build ing units to serve as nodes and spacers70-72 This strategy is based on the observa tion that the building units with center symmetry always introduce the inversion center in crystal structure. However, using noncenter symmetric building units does not guara ntee that non-center symmetric networks will be resulted. Another problem of this strategy is that although non-center symmetry network is possible, there always exists the chance that another ne twork creates inversion center by interpenetration or stacking. Nevertheless, coordi nation polymers with odd interpenetration number still have the non-center symmetry character. 2) Design of networks that are inherent in non-center symmetry73,74 Some network topologies, such as 1-D helix or (10,3)-a networks, are in noncenter symmetry. Targeting these special topol ogies will naturally provide the chances for asymmetric compounds. However, there ar e still chances of coexistence of racemic networks. 3) The host/guest coordination networks A center symmetric network could host gue st molecules in non-center symmetry arrangement. This is a phenomenon that has been observed for many examples,75,76 but there is still lack of de liberate design strategies.

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15 1.3.3. Supramolecular isomerism in coordination polymers Supramolecular isomerism, a term first coined by Zaworotko,18,69,77,78 defines “the existence of more than one superstructu re for a given set of molecular components.” It is important to note that, although supram olecular isomerism affords superstructural diversity, it also limits the number of possible architectures to those that can be generated rationally from the molecular components that are present in netw ork. The existence of supramolecular isomerism provides additiona l chances for preparing novel functional materials. Supramolecular isomers are well -known depending on the synthesis conditions that they come from.79 Therefore, finding the right conditions which favor one over another will provide the chance to co ntrol these supramolecular isomers. There are several supramolecu lar isomers in Figure 1.3. For example, helical and zigzag chain structures, A and B, are all constructed from the same building blocks, angular ditopic node and linear spacer with th e same ratio (1:1). Therefore, these two structures are isomers to each other. Based on the same principle, structures C, D, E, F are isomers constructed by “T” shape nodes a nd linear spacers buildin g units; structures H (6,3) and I (10,3)-a are isomers based on tr igonal node and linear spacer building units; and structures J (cubic diamond) and K (hexagon diamond) are isomers based on tetrahedral node and linea r spacer building units. 1.3.4. Supramolecular synthons in crystal e ngineering of coordination polymers First of all, what are synthons? According to Corey’s definition:80 Synthons are “…structural units within molecules which can be formed and/or assembled by known or conceivabl e synthetic operations”.

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16 O O H O O H Supramolecular synthons, a term introduced and defined by Desiraju,81 initially focused on the crystal engineering of molecule crystals. Its definition is presented below: “Supramolecular synthons are structural units within supermolecules which can be formed and or assembled by known or conceivable synthetic operations involving intermol ecular interactions”. Some examples of supramolecular synt hons are illustrated in Figure 1.4. They are intermolecular interac tion patterns among specific organic functional groups with stable and frequent appearances in crystal struct ures. The concept of supramolecular synthons offers a new design guideline and exerts grea t impact in the development of crystal engineering. Figure 1.4. Some examples of or ganic supramolecular synthons Expanding the concept of supramolecular synthons into all realms of crystal engineering, including coordi nation polymers, is reasonabl e since there are many metal organic chromophores that are stable, reliable and well re peated in crystal structures. Metal-organic synthon examples are disc ussed in the following two parts. O N H N O H O N H O O H N N H O O H N O O H H O O O H O H O N O H N H O O O H N H

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17 1.3.4.1. Mononuclear center mode A mononuclear center mode of coordination interaction is always in a situation that the metal ions define the geometry in th e resulted structures. Some of these examples are illustrated in Figure 1.5. Nevert heless, there are a few examples82 that metal ions are in linear geometry that can serve as linear spacers. Structure motives A, B and C are constructed from the metal ion and nitrogen atoms (mainly aromatic N atoms such as in pyridine) interactions. They are all partially terminated by a ligand or counter ions to be angular, “T” shape or square nodes, respec tively. Structure motives D, E and F are commonly seen in the transition metal (Z n, Cu, Ni and Co, respectively) carboxylate interaction fashions normally with two carboxyl ate groups attaching to one metal center. Other ligands such as pyridine and so lvent molecules will occupy the remaining positions. ________________________________________________________________________ ______________________________________________________________________ Figure 1.5. Examples of mono-metal organic (pyridine or carboxylates or both) recognition styles (synthons) A B E F D C

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18 1.3.4.2. Secondary Building Units (SBUs) In many cases, metal carboxylate interactions involve more complicated situations since there are many circumstances in wh ich the two oxygen atoms in the carboxylate group can coordinate with metal ions at the same time. If one regards monometal chromophores as “Primary Building Units”, then “Secondary Buildi ng Units (SBUs)” are given to new structure motives that involve more than one metal ion.83-90 It should be noted here that the concept of Secondary Build ing Units (SBUs) has been wildly used in the analyses of zeolite structures.91-93 In the context of metal organic coordi nation area, according to Yaghi’s definition:83 “Secondary building units (SBUs) ar e molecular complexes and cluster entities in which ligand coordina tion modes and metal coordination environments can be utilized in the transformation of these fragments into extended networks…” It should be noted that, di fferent from the monometal chromophores which metal ions normally define the nodes, it is the SBUs complexes that define the geometry based upon their own geometry features. Some of the well-known metal carboxylate SBUs are illustrated in Figure 1.6. Interestingly, they all possess high symmetry such as D4h, D3d, D3h and Td, therefore this enables them th e ability to extend themselves into welldefined predictable networks. Significance of SBUs: Control the topology of resulted product “Consideration of the geometric and chem ical attributes of the SBUs and the organic linkers leads to the pr ediction of the framework topology.”83

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19 ________________________________________________________________________ ________________________________________________________________________ Figure 1.6. Some examples of metal-carboxylate Secondary Building Units (synthons) Build robust porous structures with good thermal stability83 Secondary building units have multiple M-O coordination bonds which increase the stability of node and subsequently enhan ce the thermal stability of whole structures. Robust features of the SBU based nodes can si gnificantly reduce the chance and degree of interpenetration and incr ease the degree of porosity. Modify the structure by changing the car boxylic acid and axial directions Modular nature of SBUs endows the ab ility of systemati cally changing the building units for screening the properties. So me of the SBU have two different ways to A B E D C

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20 modify their propagation directions. For exampl e, square SBUs can be modified in both equatorial directions with carboxylates and ax ial directions with amines. (Figure 1.7) Figure 1.7. Dimetaltetracarboxyl ate, two different ways to build extended structures Construct nano-scale SBUs based on small SBUs for even larger porous structure94,95 New strategy has been used to build bigger SBU based on the small one. The new SBU will be used to build even larger nano-scaled architectures or open frameworks. 1.3.5. Examples of coordination polym ers from supramolecular synthons 1.3.5.1. Zero dimensional structures Zero dimensional structures are usua lly in nanoscale dimension with high symmetry and may contain the theoretical or practical significances. Nano-sized molecular species are aesthetically pleasi ng and also are important basic units for host/guest chemistry, catalysis, nano-tec hnology and are the building blocks for suprasupermolecular chemistry. Design principl es that are based upon the concepts of crystal engineering and self-assembly have b een applied to the construction of discrete polygons by Stang, Fujita, and Hupp et. al. Th e combination of a ngular vertices and linear spacers give enablement to make molecular architectures according to the predefined angle. Among all those reported molecular architectures, metal ions usually OR

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21 function as geometry definers and molecu lar squares (see Figure 1.8) are the most common.96-111 This is not surprising since metal ions are always in squa re or octahedral coordination environments. Pt2+ and Pd2+ metal ions are particularly useful in functioning as 90 angle ditopic building blocks. Other mol ecular architectures such as molecular triangles, pentagons, hexagons, and mol ecular polyhedra are relatively rare.21,82,112-118 ________________________________________________________________________ ________________________________________________________________________ Figure 1.8. Formation of an M4L4 molecular square Platonic and Archimedean solids119 (See Figure 1.9) are perfect design targets since they present the ideal discrete st ructures based upon high symmetry nodes and connections. Stang,21,120-122 Fujita108,123-125 and Raymond126-128 have contributed tremendously to this area. Some of the results are illustrated in Figure 1.10-1.12. N N +

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22 Platonic Solids Archimedean Solids Figure 1.9. The 5 Platonic and 13 Archimedean Solids Figure 1.10. Fifty molecules assemble to form a supramolecular dodecahedron.

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23 _______________________________________________________________________ ________________________________________________________________________ Figure 1.11. Formation of an M6L4 octahedral cage ________________________________________________________________________ ________________________________________________________________________ Figure 1.12. Formation of an M4L6 Molecular tetrahedral N N N N N N N H N H O H OH O H OH O O M + +

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24 1.3.5.2. Infinite structures The use of transition metal ions as nodes and organic ligands as spacers represents the most common approach and has afforded a wide range of 1-D,129-134 2-D61,135-146 and 3-D47,147-159 networks. Advantages to the use of metal-ligand chemistry are that it is inherently modular, that synthesis can be accomplished in one step and that transition metals can be selected for their existi ng properties as well as their geometry. Figure 1.13160 illustrates the simplest 2-D (4,4) square sheet that can be generated by using commonly available metal moieties and linking them with linear “spacer” ligands. All the metal ions are in octahedr al coordination mode with two opposite sites terminated by nitrate anions. Replacing NO3 with SiF6 2generates a perfect octahedral 3D network, which is illustrated in Figure 1.1447,161 (M = Zn2+, Cu2+). In this compound, SiF6 2ions bridge the adjacent layers. In these two networks, large ch annels are generated by 4,4’bipyridine spacers with effective dimension of ca. 8 8 2. Figure 1.15162 and 1.16163 illustrate two examples of porous network structures that are based upon square and octahedral SBUs. The compound in Fig. 1.15 possesses a (4,4) square grid sheet whereas the compound in Fig. 1.16 has a 3-D cubic topology. Since these compounds have good thermal stabi lity, because of robust SBU and excellent sorption properties, they promise practical, us eful metal-organic zeolite-like materials. Figure 1.17164 and 1.18165 illustrate two examples of chiral networks built from zinc ion and achiral and ch iral ligand, respectively. Th ese two compounds represent a new kind of functional materi al that may have special properties such as NLO, asymmetric catalysis an d chiral separations.

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25 ________________________________________________________________________ ________________________________________________________________________ Figure 1.13. Formation of (4,4) square grid by metal ions and 4,4’bipyridine in 1:2 ratio ________________________________________________________________________ ________________________________________________________________________ Figure 1.14. Formation of octahedral 3-D open-framework N N M FSiF5 FSiF5 N N + +

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26 ________________________________________________________________________ ________________________________________________________________________ Figure 1.15. Formation of (4,4) square grid by square SBU and 1,4-BDC ________________________________________________________________________ ________________________________________________________________________ Figure 1.16. Formation of cubic 3-D open-framework by octahedral SBU and 1,4-BDC O OH O O H + + O OH O O H

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27 _______________________________________________________________________ ________________________________________________________________________ Figure 1.17. Formation of dimondiod 3-D chiral networks ________________________________________________________________________ ________________________________________________________________________ Figure 1.18. Formation of (6,3) 2-D chiral open-framework + N O O O N H O O H + O OH N

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28 1.4. Summary Crystal engineering is now a highly interd isciplinary research field that requires the knowledge of mathematics, physics, chemis try, and biology from synthesis (inorganic and organic chemistry), struct ural and topology prediction, an d analysis (crystallography, mathematics) to characteri zation (thermal, absorption, ma gnetism, optical, etc) and applications (sensor, gas storage etc). It pr ovides new chances as well as challenges to modern chemists. Crystal engineering has expanded and eliminated all boundaries of traditional chemistry and will have a dramatic impact on the development of new science and technology. The big success of the recent supramolecu les approach is on the way of reaching the goal of control and predic tability. Significant progress and tremendous achievements have been seen in functiona l materials with potential applications such as: molecular recognition, gas storage,166,167 chiral molecular separation,67 magnetism,168,169 non-linear optics170 and catalysts.171,172 This progress propels Feynman’s dream173 from 40 years ago to be realized: “What would happen if we could arrange the atoms one by one the way we want them?”… “What could we do with layered st ructures with just the right layers? What would the properties of materials be if we could really arrange the atoms the way we want them? They would be very in teresting to investigate theoretically. I can not see exactly what would happen, but I can hardly doubt that when we have some control of the arrangement of things on a small scale we will get an enormously greater range of possible prope rties that substances can have, and of different things that we can do.” We shall witness a fantastic progress of this field in this new century.

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29 C C h h a a p p t t e e r r 2 2 C C o o o o r r d d i i n n a a t t i i o o n n P P o o l l y y m m e e r r s s B B a a s s e e d d u u p p o o n n Z Z n n ( ( R R C C O O2 2) )2 2( ( p p y y ) )2 2 2.1. Preamble The design principle has been discussed in Chapter 1 regarding the construction of infinite structures that are based u pon the coordination bond. The key to success in crystal engineering is to pr e-select and control supramol ecular synthons that can be utilized as building units. Thus, predictabl e networks can be created by extending metal organic synthons with multidentate orga nic ligands. The remaining body of this dissertation is focused on the design, synthe sis and characterization of novel coordination polymers based upon the pre-selected me tal organic basic building units. In the last decade, three major properties have been intensively researched in the field of metal organic coordination po lymers: porosity, non-center symmetry and magnetism. Among all reported structures, zinc( II) ion is one of the most commonly used metal ions to design novel materials with porosity and non-center symmetry. This metal ion is well known for its rich diversity of coordination modes as well as its basic building units with carboxylate ligands. It can adopt all the SBU styles listed in Figure 1.6. One of these coordination modes, mono zinc with tw o carboxylates and two pyridines, possesses a distorted tetrahedral mode, which is a good building unit for the design of non-center symmetry nets as well as porous materials. Lin and his coworkers72,164,174,175 have

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30 reported the design and syntheses of noncentr osymmetric networks that are based upon this building unit and unsymmetrical organic lig ands such as isonicotinic acid, a ligand with pyridine and carboxyl ate groups in the same compound. Some of these unsymmetrical networks exhi bit strong secondary harmonic generation (SHG) activity. According to a CSD database search, ther e are 42 hits of te trahedral mode of Zn(RCO2)2(py)2 (py = pyridine). One of the simplest examples, Zn(CH3CO2)2(py)2, CSD #ZZZPKM01, is illustrated in Figure 2.1. It should be noted that 23 structures are infinite, most of them afford the diamondoid t opology (see Figure 1.17 for one example). ________________________________________________________________________ ________________________________________________________________________ Figure 2.1. Zn(CH3CO2)2(py)2, CSD #ZZZPKM01, an example of metal organic supramolecular synthon The first strategy to build a c oordination polymer based upon Zn(RCO2)2(py)2 is to fix two directions of th is building unit with two pyr idine molecule and to use multitopic carboxylates to propagate the rema ining two directions. Two carboxylic acids are selected: 1,3-benzendicarboxylic acid (bdc ) and 1,3,5-Benzentricr boxylate acid (btc). Because tetrahedral zinc nodes, bdc and btc are all noncentr osymmetrical, the resulted coordination polymers might possess non-center symmetry.

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31 The second strategy is to extend tetrahedra l zinc node in four directions by using 4,4’,-bipyridylethane (bpeta) and bdc. Porous materials can be expected since bpeta and bdc have the length of ca. 13 and 10, respectively. 2.2. Compound 1 ---Zn(bdc)(py)2 2.2.1. Experimental Section In a typical reaction, Zinc nitrate hexahydrate (0.145g, 0.500 mmol) and 1,3benzendicarboxylic acid (0.166g, 1.00 mmol ) and pyridine (0.157g, 2.31 mmol) were added to 10.0 mL water. The solution was kept in a 40 mL vial. Colorless plate crystals 1 (0.30 x 0.20 x 0.05 mm) formed under ambient conditions. Crystals formed within days in a 29.9% (58 mg) yield based on Zn. The crystals are thermally stable up to 160 C. After which the TG curve shows a mass loss of about 30% between 160 and 250 C. Further heating leads to decomposition above 400C. The most intense peaks observed in the X-ray powder diffraction (X PD) patterns from the bulk sample are consistent with those calculated from singl e-crystal diffraction data. Selected crystallographic parameters are presented in Table 2.1. Complete crystallographic data for compound 1 can be found in Appendix A1.

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32Table 2.1. Selected crystallographic parameters for 1 Crystal system Space group (#) a () b () c () alpha () beta () gamma () V (3) Triclinic P-1 (2) 9.0833(10) 10.1744(11) 10.2319(12) 67.209(2) 74.990(2) 72.236(2) 819.46(16) Thermogravimetric analysis TGA was performed using a TA Instruments TGA 2950 thermogravimetric analyzer at a heating rate of 10 C min-1 in N2 stream. X-ray powder diffraction data for compounds 1 and all subsequent compounds described throughout this disse rtation, were collected on a Rigaku powder diffractometer with Cu K radiation in steps of 0.02 over the 3-40 angular range and a fixed-time counting of 2 seconds at 25 C. Single-crystal X-ray diffr action data for compound 1 and all subsequent compounds described throughout this dissert ation, were collected on a Bruker-AXS SMART APEX/CCD diffractometer using Mo radiation ( = 0.7107 ). Diffracted data have been corrected for Lorentz and polarization effects, and for absorption using the SADABS v2.02 area-det ector absorption correction program (Siemens Industrial Automation, Inc., 1996). The structures were solved by direct methods and the structure solution and refinement was based on | F|2. All non-hydrogen atoms were refined with anisotropic disp lacement parameters whereas hydrogen atoms

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33 were placed in calculated positions when po ssible and given isotropic U values 1.2 times that of the atom to which they are bonde d. All crystallographic calculations were conducted with the SHELXTL v.6.1 program package (Bruker AXS Inc., 2001). 2.2.2. Structural Elucidation Compound 1 was successfully synthesized with pre-designed chain structures based on the Zn(RCO2)2(py)2 tetrahedral nodes. All the bdc ligands bridge the zinc ions into one-dimensional (1-D) infinite structur es. No solvent molecule is found in this compound. Each asymmetric unit contains on e zinc atom, two pyridine molecules and one bdc molecule. The distances between Zn-O are 1.9570(18), 1.9767(18) and Zn-N are 2.049(2) and 2.032(2) . The chain structure is illustrated in Fi gure 2.2, in which all the carboxylate groups are lying on the same side of the metal ion a nd all the pyridines on the other. Each chain structure is roughly straight. The combinati on of tetrahedral and angular spacer creates non-center symmetry in the resulted coordi nation polymer. However, the adjacent chain with opposite polar orientation closes it by in terdigitation and cancels it. Therefore, the bulky phase is centrosymmetric. The racemic dimmer of chains propagates itself by overlapping phenyl groups of caboxylate in bc plane and stacks each other along a axial direction by interdigitating of pyridine groups. There are C-H… and … interactions between layers (the C… centroid distance is 3.532 and the centroid… centroid distances are 3.611 and 3.705, consistent with distances to be expected for such interactions).

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34 ________________________________________________________________________ ________________________________________________________________________ Figure 2.2. Racemic chain dimer (a) and their packin g view along bc plane (b) and in a axial direction (c) in compound 1 (a) (b) (c)

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35 2.3. Compound 2 -Zn1.5(btc)(py)3•1.5H2O 2.3.1. Experimental Section In a typical reaction, a clear water so lution (10.0 mL) of pyridine (1.54 g, 2.26 mmol), zinc nitrate hexahydr ate (0.145g, 0.500 mmol) and 1,3,5-be nzentricrboxylate acid (0.212 g, 1.00 mmol) was kept in a 40 ml vial. The colorless plate crystal 2 (0.1 x 0.2 x 0.2 mm3) was found overnight. Yield: 118 mg or 62% based on Zn. The crystals are thermally stable up to 170 C after which the TG curve shows a mass loss of about 35% between 170 and 230 C. Further heating lead s to decomposition above 400C. The most intense peaks observed in th e X-ray powder diffraction (X PD) patterns from the bulk sample are consistent with those calcul ated from single-crys tal diffraction data. Selected crystallographic parameters are presented in Table 2.2. Complete crystallographic data for compound 2 can be found in Appendix A2. Table 2.2. Selected crystallographic parameters for 2 Crystal system Space group (#) a () b () c () beta () V (3) Monoclinic I2/a (15) 16.7655(15) 15.5285(14) 17.9717(16) 93.623(2) 4669.5(7) 2.3.2. Structural Elucidation Compound 2 was obtained from the reaction of zi nc-pyridine-btc in aqueous solution based on the Zn(RCO2)2(py)2 tetrahedral nodes. Each node is terminated by two pyridine

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36 molecules and bridged by two carboxylate groups. Each btc ligand bri dges three zinc ions into a two-dimensional (2-D) in finite layer structure. There are one and half zinc atoms, three pyridine molecules, one btc molecule and one and half water molecules in the asymmetric unit. The distances between Zn -O are 1.929(2), 1.953(2), 1.929(2) and ZnN are 2.029(3), 2.027(3), and 2.026(3) . In th is compound, the combination of angular ditopic nodes with planar tri gonal ligands in 2-D sheet cr eates a layer structure as illustrated in Figure 2.3. Careful examination of the sheet structure reveals that it is constructed from the same basic unit, a mixed convex and concave circle constructed fr om six zinc nodes and six btc molecules. (See Figure 2.3 a) In each circle, three of the si x zinc nodes point into each other with pyridine molecu les. Water molecules are occupied in these channels. The total volume occupied by guest mo lecules in this structure is ca. 6.5%. The layers stack each other by inte rdigitation with interlayer distance ca. 4.0 . The layer is undulated due to the … interactions between the carboxylate benzene ring of adjacent layers. (See Figure 2.3 b)

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37 ________________________________________________________________________ ________________________________________________________________________ Figure 2.3. Overhead (a) and pers pective (b) views of the two di mensional network seen in the crystal structure of Zn1.5(btc)(py)3, 2. 2.3.3. Network topology The primary interaction in compound 2 is coordination bonds between carboxylates and zinc ions. Part ially terminated zinc tetrah edral node has two connecting positions and functions as an angular ditopic node. Therefore it is replaced by an angular node. The btc molecule is predisposed to a tr igonal planar geometric arrangement (i.e. at (a) (b)

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38 120 with respect to one anothe r). Therefore, it is repla ced by a trigonal node (Figure 2.4). Figure 2.4. Schematic representatio n of zinc and trimesate nodes The reduction of the molecules to a si ngle node results in the removal of the carbon, hydrogen, nitrogen, and oxygen atoms. Th e schematic representation in Figure 2.5 illustrates the framework of the crystal struct ure. The ideal situation of this network is a periodical plane tiling with dodecagon. It is a pattern that can be found in a sidewalk or parking lot. The most striking feature of this 2-D network is that it possesses non-center symmetry. Moore and his coworkers176 reported a similar network. Unfortunately, just like compound 1 the adjacent layer with opposite dire ction offsets the original network and the bulk crystal is in center symmetry.

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39 _______________________________________________________________________ ________________________________________________________________________ Figure 2.5. Schematic illustration of Zn1.5(btc)(py)3, 2. 2.4. Compound 3 -[Zn(bdc)(bpeta)]n. x (guest)177 ( 3a-3e ) 2.4.1. Experimental Section The compound, [Zn(bdc)(bpeta)]n x (guest) (3a-3e) were prepared by dissolving zinc nitrate hexahydrate ( 0.149 g, 0.500 mmol) and 1,3-benzenedicarboxylic acid (0.166 g, 0.999 mmol) in ethanol and layering this with a solution of 1,2-bis(4-pyridyl)ethane (0.184 g, 1.00 mmol) in 10.0 mL different solven t. Colorless rod-shaped crystals 3a-e were formed at the solvent interface [i.e., benzene ( 3a ), nitrobenzene ( 3b ), toluene ( 3c ), benzaldehyde ( 3d ) or 1,4-dioxane ( 3e )]. The crystals are unstable and ready to release guests after leaving mother liquid. Crystals formed within days in ca 30% yield based on Zn. The crystals are thermally stable up to 150 C after which the TG curve shows a mass loss of about 33% between 180 and 300 C. Further heating leads to decomposition above 400C.

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40 Selected crystallographic parameters are presented in Table 2.3. Complete crystallographic data for compound 3a-e can be found in Appendix A3-A7. Table 2.3. Selected crysta llographic parameters for 3a-e Crystal system Space group (#) a () b () c () beta () V (3) 3a Monoclinic P2(1)/n (14) 9.6724(10) 20.217(2) 14.9774(15) 93.545(2) 2923.2(5) 3b Monoclinic P2(1)/n (14) 10.5457(15) 18.400(3) 15.209(2) 90.971(3) 2950.8(7) 3c Monoclinic P2(1)/n (14) 10.243(3) 18.317(5) 15.391(4) 91.116(5) 2887.3(13) 3d Monoclinic P2(1)/n (14) 10.437(2) 18.516(4) 15.190(3) 90.119(4) 2935.6(10) 3e Monoclinic P2(1)/n (14) 10.5454(13) 20.202(2) 14.2392(17) 96.781(2) 3012.3(6) 2.4.2. Structural Elucidation The covalent networks in 3a-3e have the same fashion except the different guest solvent molecules. They are all sustained by a tetrahedral Zn(II) ion coordinated to two bdc and two bpeta ligands. Each bdc and bpeta ligand bridges two zi nc ions into a 2-D (4,4) network in which zinc ion actually serv es as pseudo-square node. There is one zinc atom, one bpeta molecule, and one bdc molecule in every asymmetry unit. In the following text, compound 3a is used as a representative for all compound 3’s since they have similar structures. In compound 3a the bond distances of Zn-O are 1.947(2) and 1.9500(19) and Zn-N are 2.043(2) and 2.061(2) . The tetrah edral geometry around the zinc ion causes adjacent rectangular cavities to fold with an angle of 99.94 between Zn ions, producing a ‘puckered’ layer of cavities, as illustrated in Figure 2.6. Adjacent cavities have slightly

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41 different environments in that the orientation of the aromatic rings of the bdc units differ: in one (cavity A) the rings are coplanar with the plane of the cavity, while for the next cavity (B) opposite bdc moeities point up and down with respect to the plane of the cavity. Effective dimensions for the cav ities are 4.8 x 13.3 (for A) and 6.0 x 13.6 (for B). The bpeta ligands c ontain pyridyl rings wh ich are only slightly twisted (torsion angle 167.7 ) and these ligands are bowed when viewed down the Zn…Zn direction as illustrated in Figure 2.7 (a). The coordination polymer layers pack closely to one another in AAA fashion, with metal centers a nd cavities stacked above one another, when viewed down [1 0 0]. The interlayer separation is 9.7 and there are C-H… and … interactions between layers (the C… centroid distance is 3.532 and the centroid… centroid distances are 3.611 and 3.705, consistent with distances to be expected for such interactions).

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42 ________________________________________________________________________ ________________________________________________________________________ Figure 2.6. Space-filling of perspective (a) and side view (b ) of the puckered rectangular grid coordination polymer network in 3a Cavity A Cavity B (a) (b)

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43 The organic guest molecules in 3a-e form what could be regarded as (6,3) “puckered brick wall” networks that are su stained by noncovalent in teractions. Figure 2.7 (b) illustrates how two of the noncovalent networks engage in parallel interpenetration with the coor dination polymers, thereby form ing a self-interpenetrated structure. A view of the noncovalent nets that are formed by benzene molecules in 3a is illustrated in Figure 2.8. A network topology il lustration of this puckered grid is illustrated in Figure 2.9. ____________________________________________________________________________________________________________ ________________________________________________________________________ Figure 2.7. An illustration of (a) packing view of the puckered grid and (b) how two noncovalent networks (illustrated in space-f illing mode) generate parallel int erpenetration with one puckered rectangular grid (illustrate d in stick mode) in 3a. (a) (b)

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44 ________________________________________________________________________ ________________________________________________________________________ Figure 2.8. A view of the noncovalent nets that are formed by benzene molecules in 3a Figure 2.9. Schematic illustration of puckered grid [Zn(bdc)(bpeta)]n, 3. O O O O N N ZnII Solvent + +

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45 2.5. Compound 4 -[Zn(bdc)(bpeta)]n x (small guest)177 ( 4a and 4b ) 2.5.1. Experimental Section [Zn(1,3-bdc)(bpeta)]n (guest) compounds, 4a, 4b were prepared by dissolving zinc nitrate hexahydrate ( 0.149 g, 0.500 mmol) and 1,3-benzenedicarboxylic acid (0.166 g, 0.999 mmol) in 10.0 mL ethanol and layering this with a solution of 1,2-bis(4pyridyl)ethane (0.184 g, 1.00 mmol) in the 10 mL guest solvent. (Guest molecules: dichloromethane ( 4a ), methanol ( 4b ) with naphthalene (0.155 g, 1.21 mmol)). Colorless rod-shaped crystals were formed at the solven t interface. Crystals formed within days in ca. 40% yield based on Zn. The crystals are th ermally stable up to 300 C after which the TG curve shows a mass loss of about 65% between 300 and 500 C. The most intense peaks observed in the X-ray powder diffracti on (XPD) patterns from the bulk sample are consistent with those calculated fr om single-crystal diffraction data. Selected crystallographic parameters are presented in Table 2.4. Complete crystallographic data for compound 4a and 4b can be found in Appendix A8 and A9. Table 2.4. Selected crystallogr aphic parameters for 4a and 4b Crystal sytem Space group (#) a () b () c () V (3) 4a Orthorhombic Pnna (52) 10.0200(10) 15.1945(15) 13.6885(13) 2084.1(4) 4b Orthorhombic Pnna (52) 9.676(3) 15.470(5) 13.547(5) 2027.9(12)

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46 2.5.2. Structural Elucidation The covalent networks in 4a-4b are exactly the same except they possess different solvents. Compound 4a is used to give structure illu stration in the following context. Compounds 4 which exhibit dramatically diffe rent structures from compounds 3, can be described as a pseudotetrahedral framework because the tetrahedral Zn ions are linked by angular and linear sp acer ligands. There are ha lf zinc atom, half bpeta molecule, and half bdc molecule in every asym metric unit. The zinc atom sits in a twofold axis, which generates another half zi nc atom, bdc and bpeta molecules. In compound 4a the distance between Zn-O is 2.007(2) and Zn-N is 2.059(2) . Zn-Zn separations in 4a are 9.90 and 13.24. The structure details are illustrated in Figur e 2.10. First, zigzag chains are formed by coordination between zinc ions and bdc molecules. Second, zigzag chains are connected by bpeta which results in a (6.3) br ick wall like layer stru ctures. Finally, these layers are further crosslinked into a di storted diamondoid-like network by bpeta. A skeleton schematic figure is illustrated in Fig 2.11 (only zinc atoms and their direct connection). This 4-connected netw ork has the circuit symbol of 6482. The large void generated within the pseudo-diamondoid cage is filled by the mutual interpenetration of three-dual independent networks. (Fig. 2.11) Guest molecules in 4a occupy cavities inside the metal-coordination networks, and are isolated fr om one another. The total volume occupied by guest molecu les in this structure is ca. 17.6%.

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47 ________________________________________________________________________ ________________________________________________________________________ Figure 2.10. (a) a (6,3) network built from Zn/bdc zigzag chain and bpeta, (b) the crosslinking of (6,3) network by another bpeta __________________________________________________________________________________________ Figure 2.11. The pseudo-diamondoid network in 4a. The bridging ligands are replaced with straight lines that connect zinc nodes. (a) (b)

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48 ________________________________________________________________________ ________________________________________________________________________ Figure 2.12. An illustration of th e three pseudo-diamondoid networks that interpenetrate in 4a 2.6. Discussion and Conclusions Crystal engineering for the design of coordination polymers depends on the control of network topology and subsequent ly changing their properties. Judicious selection of building blocks and focusing on sp ecific metal-organic synthons are critical for the manipulation of structure in an accura te way. The study in this Chapter focuses on the extension of the network with multidentate organic ligands based upon Zn(RCO2)2(py)2 a coordinated tetrahedral node w ith two carboxylate and two pyridine function groups around zinc ion.

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49 Previous works by Lin178, Zhao179 and Zaworotko180 have demonstrated the feasibility of using Zn(RCO2)2(py)2 tetrahedral nodes to build unsymmetrical 3-D dimondiod, quartz and novel 4284 networks. These results show that Zn(RCO2)2(py)2, a zinc chromophore, is stable, reliable and well repeated, so it can be used as a supramolecular synthon. Compound 1 and 2 represent the simplest idea to generate networks by using zinc, multidentate carboxylic acids (bdc and btc) and pyridine. It is our design that this approach might result in networks without center symmetry since the zinc tetrahedral node, bdc and btc are al l building units with out center symmetry. Unfortunately, the bulk phases are in center symmetry because of racemic stacking of networks. Although, this is in fact a common phenomenon181 when achiral building units are used to design noncetrosymmetric topology, it still inspires us the further research. For example, to use acids with tetrah edral symmetry, such as adamantane-1,3,5,7tetracarboxylic acid, may produce 3-D networ ks without center symmetry. Modification of the ligands with some function groups182 might create strong H-bond interactions between the chains or layers so that the racemic stacking can be avoided. In contrast, compounds 3 and 4 possess center symmetry since bpeta is a molecule with center symmetry. Future research atte mpts should focus on replacing bpeta with other ditopic pyridines that have non-center symmetry, but still can function as linear spacers. Zaworotko62 has previously studied the diam ondoid network based on tetrahedral nodes. It has been suggested that two diffe rent topologies, 2-D puckered sheet and 3-D diamondoid structures are possibl e network topologies. Compounds 3 and 4 reveal the

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50 existence of both suggested networks under diffe rent synthetic conditions in our research system. Actually, two networks have the same formula and are supramolecular isomers. The topology consideration75,183,184 has been suggested by Zaworotko’s research group to explain interpenetrati on of two very different type s of nets: 2-D square grids formed from octahedral metal ions coordinate d to two linear bifuncti onal ligands, such as 4,4’bipyridine and planar noncovalent nets comprising organic guest molecules. Compounds 3a-3e exhibit another examples of the coexistence of coordination polymer and noncovalent nets via a parallel interpenetration mode, which is possible because the coordination polymer exists as a novel puckered 2-D grid. The absence of a suitable component for the noncovalent nets precludes the formation of the 2-D coordination polymer, and instead affords a novel 3-D supramolecular isomer of the coordination polymer. It is fundamentally important for supr amolecular chemistry to find and control supramolecular isomers. The existence of supramolecular isomers 3 and 4 provide a new example on how to control their formation by controlling synthetic conditions such as solvents. In conclusion, four different netw orks are generated by propagating the tetrahedral node, Zn(RCO2)(py)2. Predictable networks which range from 1-D to 3-D are thus produced. It is clear that this strategy can control the positions of two different kinds of ligands in the resu lted networks, and ther efore it could be used as a model method to generate the same kind of networks. The making of crystals is now in a rational way – we know where and how the molecules will go into the crystals and consequently, we can control their topologies as well as properties.

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51 2.7. CSD Database studies of Zn(RCO2)2(N)2 A CSD database search has been carrie d out to compare these reported crystal data with our obtained crystal data. The c oordination of Zn(II) with two N-donor and two carboxylate has generated different types of 4-connected nodes, in which the carboxylate function can adopt monodentate or bidentate coordination to metal center. A survey of the CSD revealed that out of 70 non-e quivalent chromophores containing the mononuclear Zn center coordinated to two nitrogen donor and two oxygen carboxylate, 16 exhibit the bidentate c oordination mode of the car boxylate moieties, 54 the monodentate mode and in par ticular, 42 exhibit the Zn(RCO2)2(py)2 chromophore. As our compounds are exclusively in monode ntate mode, the statistic results are calculated only based upon 54 structures that are in the same mode. As illustrated in Table 2.5, the Zn-N distances range between 1.987 and 2.095 with an average of 2.039 (standard deviation = 0.028). The distances between Zn and bonded oxygen vary between 1.844 and 2.031 (average 1.963 , = 0.027). The statistic results of 11 compounds from this work are also included in the same table. The results show that the Zn-N distances range between 2.008 and 2.073 with an average of 2.041 ( = 0.017), the distances between Zn and bonded oxygen vary between 1.929 and 2.007 (average 1.957 , = 0.021). Clearly, the bond distances fr om our crystal structures are under normal conditions for their similarities to that of reported crystal structures.

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52 Table 2.5. Zinc tetrahedral with two nitrogen atoms and two carboxylates Zn-Oa Zn-Na Zn-Ob Zn-Nb Min 1.844 1.987 1.929 2.008 Max 2.031 2.095 2.007 2.073 Average 1.960 2.039 1.957 2.041 Median 1.963 2.036 1.954 2.044 STDVA 0.027 0.028 0.021 0.017 a: 54 hits from CSD da tabase, b: this work

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53 C C h h a a p p t t e e r r 3 3 T T h h r r e e e e D D i i m m e e n n s s i i o o n n a a l l S S t t r r u u c c t t u u r r e e s s B B a a s s e e d d u u p p o o n n Z Z n n2 2( ( R R C C O O2 2) )4 4 a a n n d d Z Z n n2 2( ( R R C C O O2 2) )3 3 S S B B U U s s 3.1. Preamble The ubiquitous dimetaltet racarboxylate cluster, M2(O2CR)4, is a common structural motif. Hundreds of such structures are found in CSD and the metal can be Cu, Zn, Co, Ni, Mo, Re, Rh, etc. Dime taltetracarboxylate complexes [(M2(O2CR)4), a unit which is constructed from two metal ions and four carboxylates, is on e that has been well studied over three decades especially pioneered by F.A. Cotton.185 A search of Cambridge Structural Database (CSD) (CCD C 2004 Conquest Version 1.6) reveals that there are more than 1,000 entrie s for such a structure unit. Mo re than half of transition metal elements possess this unit and Cu, Rh, Ru, Mo, and Cr constitute most of them. (See Table 5.8 in the last part of Chapter 5) Recent development of design and synthe ses of new supramolecular networks have been largely prompted by the applicati on of the concept of cr ystal engineering. Of particular interests are these hydrogen or coor dination bonded infinite structures with the ability to reversible absorption/desorption guest or small molecules. These materials have potential applicati ons in gas storage,186 catalysis,171,187 and magnetism 188,189 190,191etc.

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54 Figure 3.1. SBU based upon M2(carboxylate)4 – a supramolecular synthons with a square molecular shape It has been demonstrated that the use of poly carboxylate ligands83,162,192-198 in dimetal tetracarboxylate complexes, M2(RCO2)4 (Figure 3.1), affords self-assembled infinite structures with pr edictable topology and relatively high thermal stability. It therefore occurred to us that complexation of the angular trifunctional ligand benzene1,3,5-tricarboxylate (btc) should also afford predictable in finite networks. Indeed, complexation of btc with Zn (II) affords two remarkable new structures that represent prototypes for porous struct ures that are based upon faceted uniform polyhedra.199 =

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55 3.2. Compound 5 -{[Zn2(btc)]8[Zn2(btc)1.333]3}n 3.2.1. Experimental Section In a typical reaction, a solution of Zn(NO3)2 6H2O (220 mg, 0.741 mmol) and 1,3,5-benzenetricarboxylic acid (220 mg, 1.05 mmol) in methanol (10.0 mL) was layered onto a solution of nitroben zene (10.0 mL) containing pyr idine (0.23 mL, 2.8 mmol). Large single crystals 5 (0.30 x 0.30 x 0.15 mm3) formed within hours under ambient conditions. Yield: 85 mg, 47% based on Zn. The compound slowly lost crystallinity after being taken out from the mother liquor in room temperature. TG curve shows a continuous mass loss of about 64% between 50 and 500 C. Selected crystallographic parameters are presented in Table 3.1. Complete crystallographic data for compound 5 can be found in Appendix A10. Table 3.1. Selected crystallographic parameters for 5 Crystal system Space group (#) a () = b () = c () V (3) Cubic Pm-3m (221) 20.4702(11) 8577.6(8) 3.2.2. Structure Elucidation Compound 5 is crystallized in a high symmetry space group, cubic Pm-3m. Its molecular components, btc and znic atoms, are clearly il lustrated in the framework. However, solvent molecules are disordered a nd can not be recognized from crystal data. There are three crystallographically inde pendent zinc atoms, three independent oxygen atoms and six independent carbon atoms in one asymmetry unit. After symmetry

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56 operation, two dizinc chromophores (SBUs) are found in the framework: dizinc tricarboxylate -Zn2(RCO2)3 and dizinc tetracarboxylate -Zn2(RCO2)4, as illustrated in Figure 3.2. All zinc ions and bt c molecules are involved in SB Us. There are three dizinc tetracarboxylate groups, eight di zinc tricarboxylate groups an d twelve btc molecules in every unit cell that give a formula {[Zn2(btc)]8[Zn2(btc)1.333]3}n for this compound. In each of Zn2(RCO2)3 SBUs, Zn-Zn distance is 3.511 and Zn-O distance is 1.92(3) and 1.95(2) . In each of Zn2(RCO2)4 SBUs, Zn-Zn distances is 2.968(12) and Zn-O distance is 2.01(2) . These two chromophores (SBUs) have been known for a long time. There are 11 structures containing Zn2(RCO2)4 SBU and 15 struct ures containing Zn2(RCO2)3 SBU in CSD database(CCDC 2004 Conquest Version 1.6). In each of dizinc tricarboxylate SBU, th ere are only three carboxylate groups to balance two zinc (II) ions. So, every such SBU has one positive charge. Therefore, the framework is cationic. Nitrate groups are th e most probable balance anions. However, no anions are found from crystal data. These anio ns are most probably located at the axial positions of dizinc tricarboxylate SBU. The framework of 5 is low in density. The cal culated densities are 0.627 kg/m3 and 0.413 kg/m3 based upon formula [Zn2(btc)]8[Zn2(btc)1.333]38NO3(py)14 and [Zn2(btc)]8[Zn2(btc)1.333]38NO3, respectively. The free volume of the desolvated structure (calculated using Cerius 2) is about 75.6 % for 5

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57 (a) 1x1x1 viewed down [001] (b) viewed down [011] (c) vi ewed down [111] Figure 3.2. Molecular and Space filling models of compound 5, {[Zn2(btc)]8[Zn2(btc)1.333]3}n 3.2.3. Network Topology The first step taken here is to simplify the structure with node and spacers. There are three nodes in this stru cture, tetracarboxylat e SBU, tricarboxylate SBU and btc. The tetracarboxylate SBU is simila rly represented by a square nod e, by treating the two zincs as a single node that orient s the carboxylates at 90 with respect to one another (As illustrated in Figure 3.3). Tricarboxylate SBU a nd btc are replaced with planar trigonal

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58 nodes with different colors. They are all perfect in the three directions at 120 with respect to one another. Figure 3.3. Schematic representatio n of dizinc SBU and trimesate The simplification of the network with th ree different nodes results in the removal of carbon, hydrogen, oxygen, and zinc atoms. Th e new structure in the same topology is

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59 illustrated in Figure 3.4. If we consider the enti re trigonal planar nodes to be same (there is a slight difference in distance between Nbtc and NZn4 5.141 and Nbtc and NZn3 5.371 , N = node), the network is a three (trigonal plan ar) and four (square planar)-connected nets in cubic system with the ratio of 20:3. As a result, this net c ould be described with the circuit symbol (83)(84122). Note: there are two different 8-member rings. One is constructed from 8 trigonal nodes. The othe r is constructed from 6 trigonal nodes and two square nodes. ________________________________________________________________________ ________________________________________________________________________ Figure 3.4. Schematic represent ation of (3,4)-connected net of compound 5 after first simplification The structure above after simplification sti ll can not give us a precise picture of what this high symmetry network is about. There is also no mention in Wells’ book regarding the “three-dimensi onal (3,4)-connected nets”. However, related information was found in “some nets with cubic symmetry”, in which he described that networks with

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60 cubic symmetry could be viewed as the p acking of polyhedron. Obviously, no planes can be found in Figure 3.4 immediately based on di rect connection of nodes. But there are planes that are defined by nodes. Figure 3.5 illu strates that each zinc square node in fact is sitting in the middle of a square plane wh ich is defined by four btc trigonal nodes and each zinc trigonal node is sitting in the middl e of a triangle plane which are defined by three btc trigonal nodes. If all these zinc nodes are then omitted, the topology of compound 5 changes into a 6-connected net in Pm-3m space group. It is now easy to identify that this net is co nstructed from rhombicuboctahedr a/cuboctahedra/cubes (1:1:3); which Andreini and Wells had already discussed.200,201 ________________________________________________________________________ ________________________________________________________________________ Figure 3.5. Schematic represe ntation of compound 5 with square and triangle

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61 It is necessary to note that in Figu re 3.5, all triangles are covered by dizinc triangle SBUs. Only half of the square f aces, however, are covered by dizinc square SBUs. The other half is empty and creates open channels illustra ted in Figure 3.2 (b). Moreover, if all these triangle SBUs and squa re SBUs are displaced with red triangles and green squares, a new pictur e is illustrated in Figure 3.6. ________________________________________________________________________ Figure 3.6. (a)The secondary building units (SBUs) employed for the construction of faceted polyhedra; (b) crystal structure and schema tic illustration of 5 view along the [001] crystallographic plane. (a) (b)

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62 Finally, the basic building polyhedra (r hombicuboctahedra, cuboctahedra, and cubes), both schematic and molecular versi ons, are extracted from the network as illustrated in Figure 3.7. A rhombicuboctahedr on is composed of eight tricarboxylate SBUs and eight dizinc tetracarboxylate SB Us. A cuboctahedron is composed of only eight dizinc tricarboxylate SBUs. The cubes are void spaces that have no SBUs around it. Rhombicuboctahedra and cuboctahedra are polyh edra that are partially occupied with faces. They belong to the uniform pol yhedron family called “faceted polyhedra”. Therefore, more accurate terms for th em are “small cubicuboctahedron” and “octahemioctahedron”. The btc molecules are the joint points for the packing of molecular polyhedra since it is the only posit ion that the 3-D stru cture could propagate. SBUs are also shared by these polyhedra that pack each other. The separation distance betw een opposite faces of a sm all cubicubocthedron is 2.05 nm and the dimensions of the windows are about 0.9 nm. The effective interior diameter is 15.5 with effective volumes ca. 1.95 nm3. The separation distance between opposite faces of an octahemioctahedron is 1.07 nm and the dimensions of the windows are about 0.8 nm. The effectiv e interior diameter is 1 nm with effective volumes ca. 0.3 nm3.

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63 Figure 3.7. Small cubicuboctahedra and octahemioctahedron extracted from 5

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64 3.3. Compound 6 – [L2Zn2(btc)4/3]n 3.3.1. Experimental Section A solution of Zn(NO3)26H2O (202 mg, 0.679 mmol) and 1,3,5benzenetricarboxylic acid (126 m g, 0.600 mmol) in methanol (10.0 mL) was layered onto a solution of benzene (10.0 mL) containing pyridine (0.10 mL; 1.24 mmol). Large single crystals 6 (0.30 x 0.25 x 0.20 mm3) formed within hours under ambient conditions. Yield: 105 mg, 49% based on Zn. The compound slowly lost crystalline after taken out from mother liquor in room temperature. TG cu rve shows a mass loss of about 64% between 100 and 450 C. Selected crystallographic parameters are presented in Table 3.2. Complete crystallographic data for compound 6 can be found in Appendix A11. Table 3.2. Selected crystallographic parameters for 6 Crystal system Space group (#) a () = b () = c () V (3) Cubic Fm-3m (225) 26.5367(13) 18687.0(16) 3.3.2. Structure Elucidation Compound 6 is also crystallized in a hi gh symmetry space group, cubic Fm-3m. btc molecules and zinc ions are clearly illu strated in the framework with disordered solvent molecules located inside the framewor k. A similar structure with Cu as the metal ion has been previously reported by Williams et. al.202 In the crystal structure of compound 6 there is: one crystallographically independent zinc atoms, one independent oxygen atoms and three independent carbon

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65 atoms in one asymmetry unit. After symm etry operation, only di zinc tetracarboxylate SBU-Zn2(RCO2)4, is found in the framework as illustra ted in Figure 3.8. All zinc ions and btc molecules are involved in SBUs. Ther e are 24 dizinc tetracarboxylate groups and 32 btc molecules in every unit cell that give a formula [Zn2(btc)1.333]24n for this compound. In each of Zn2(RCO2)4 SBU, Zn-Zn distance is 2.9489(17) and Zn-O distance is 2.018(3) . No solvent molecu les are found from crys tal data. The most probable solvents are pyridine, methanol or water. (a) 1x1x1 viewed down [001] (b) viewed down [011] (c) vi ewed down [111] Figure 3.8. Molecular and Space filling models of compound 6, [Zn2(btc)1.333]n The calculated framework densities are 1.16 kg/m3 and 0.866 kg/m3 based upon formula [Zn2(btc)1.333](py)2 and [Zn2(btc)1.333], respectively. The free volume of the desolvated structures (calculated using Cerius 2) is about 70.3 % for 6

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66 3.3.3 Network Topology The crystal structure of compound 6 can be reduced in the same way as that of compound 5 In this instance, however, the material is sustained by square dizinc SBUs only. A new (3,4)-connected net is illustrated in Figure 3.9 by replac ing dizinc square SBUs and btc with square nodes and triangle nodes. This is anothe r example of three (trigonal plane) and four (square plane)-connected nets in cubic system with the ratio of 4:3. This net has a circuit symbol of (63)(6282122). ________________________________________________________________________ ________________________________________________________________________ Figure 3.9. Schematic represent ation of (3,4)-connected net of compound 5 after first simplification Once again, by connecting the centers of the trimesate trigonal nodes such that they surround the SBU nodes as illustrated in Figure 3.10, if all s quare nodes are then omitted, a 6-connected net with cubic Fm3m sy mmetry is resulted finally. It is the net

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67 that is constructed from rhombicuboctahedra, cubes and tetrahedra w ith the ratio of 1:1:2. Figure 3.11 illustrates the schematic illustrati on of network after square SBUs are replaced by green squares. ________________________________________________________________________ ________________________________________________________________________ Figure 3.10. Schematic representatio n of compound 6 with square ________________________________________________________________________ __________________________________________________________________________________________ Figure 3.11. Crystal structure and schematic illustration of 6 view ed along the [001] crystallographic plane

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68 Figure 3.12. Small rhombihexahedron extracted from 6 The rhombicuboctahedra, sustained by 12 squares alone, is extracted from the crystal structure as illustrated in Fi gure 3.12. This faceted polyhedron is named small rhombihexahedron It is slightly larger than the s mall cubicuboctahedra seen in 5 It has a diameter of 2.30 nm and its windows have dimensions of about 0.9 nm. The effective interior diameter is 14.3 with effective volumes ca. 1.53 nm3. 3.4. Discussion The node and spacer mode, which is normally used to facilitate the understanding of the topologies of coordination polymers, is not very useful in these two cubic

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69 compounds. The further simplification of us ing polygons to replace planar arrangements of nodes provides the structural details of ba sic building units (i.e. faceted polyhedra) as well as packing styles. This new method could be valuable for the future illustration of other similar complicated structures. Frameworks built from coordination bond between metal ion and multidentate carboxylic acids have been demonstrated as useful porous materials with good thermal stability for gas storage,203-205 host/guest172,197,206 and magnetic207 purpose. There are several directions that have been addressed for the design of networks. Metal ions Metal-carboxylate supramol ecular synthons (SBUs), Dimension of carboxylic acid Size of ligands Compounds 5 and 6 are synthesized from the same starting reagents (Zn(II) and btc). They are all in high symmetry cubic crystal class with nano pores, channels and spherical cavities inside the structures. They both are constructed from faceted polyhedra. Compound 5 is ionic. It has trigonal and square dizinc SBUs in the same structure. Compound 6 is neutral. It has only square dizinc SBUs. Interestingly, a one-fold (10,3)-a chiral network, which is constructed from di zinc trigonal SBUs a nd btc, was reported by Yaghi et.al.208 The crystal structures of 5 and 6 can be described as being composed of molecular squares (green) and triangles (red) that self-assemble into small cubicuboctahedra and small rhombihexahedron because two of the btc car boxylate moieties impose a 120 angle at the linkage between the polygons (see Figure 3.13). The overall structure

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70 contains channels and cavities that are enti rely predictable based upon the dimensions of the square SBU, triangle SBU, and btc. No tably, the dihedral angle imposed by the btc ligands (120) is close to th e ideal angle of 125.16 and 120 th at would exist in a perfect small cubicuboctahedron and small rhombihexahedron. ________________________________________________________________________ _________________________________________________________________________________________ Figure 3.13. An illustration of how the vertices of the molecular squares and triangles connected by the btc moieties In principle, the design of co mpounds with the same topology as 5 and 6 from other metal ions is possible since many metal ions have similar coordination environments with carboxylic acids. Compound 5 is more complicated since it requires two different SBUs at the same time. However, compound 6 is relatively simple and 120 120

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71 feasible. Actually, it has been pointed out that a copper (II) analogue has already been reported. The variation of carboxylic acids is another directi on. A similar compound, which is constructed from dicopper te tracarboxylate and a gi ant tridentate carbo xylic acid [4, 4’, 4’’-benzene-1, 3, 5-triyl-tribenzoic acid (H3BTB)], was reported by Yaghi et.al.209 This compound also possesses a (3,4)-connected net but in Pt3O4 topology. The difference is that three carboxylate gr oups of btc in compounds 5 and 6 are almost in the same plane while three carboxylate groups of BTB are not. This differen ce causes the different 3-D arrangement of square SBUs and results in different symmetry. It occurs to us that keeping three carboxylate groups of ligand molecu les at the same plane is critical for the synthesis of identical ne twork topologies as in 5 and 6 The last question is: Can we make thes e faceted polyhedra? Actually there are nine known faceted polyhedra illustrate d in Figure 3.14. Three of them, small cubicuboctahedra, small rhombihexahedron and octahemioctahedron, are found in this work. In fact, some of these nine facete d polyhedra, such as tetrahemihexahedron123,210, octahemioctahedron211 and small cubicuboctahedron212,213, have already been reported from metal-organic systems, although not all of authors realized that they have made faceted polyhedra. Because all the structure information of those faceted polyhedra (Figure 3.7 and Figure 3.12) is available, the next step is st raightforward – changing the acid from btc to bdc. The experiments were then carried out and small rhombihexahedron was successfully synthesized together with other interesting results when Cu2+ is used as metal ion. These results are summarized in Chapter 4.

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72 In conclusion, we have demonstrated th at molecular polygons can self-assemble at their vertices to produce molecular arch itectures and crystal structures that are consistent with long-established geometric c onstraints. These struct ures therefore differ in terms of design and function from structur es that are generated from Platonic and/or Archime-dean building blocks. The strate gy represents a pote ntially broad-ranging approach to the design of nanoporous structures from a wide range of chemical components that are based upon molecular shap e rather than a chemical formula. In effect, we present another example of th e “Molecular Meccano” approach to selfassembled structures. Figure 3.14. Schematic illustration of the nine possible faceted polyhedra small rhombihexahedron small rhombidodecahedron cubohemioctahedron small dodecicosidodecahedron small dodecadodecahedron small cubicuboctahedro n small icosihemidodecahedron octahemioctahedron tetrahemihexahedron

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73 C C h h a a p p t t e e r r 4 4 S S e e l l f f A A s s s s e e m m b b l l e e d d S S u u p p r r a a m m o o l l e e c c u u l l e e s s B B a a s s e e d d u u p p o o n n D D i i c c o o p p p p e e r r T T e e t t r r a a c c a a r r b b o o x x y y l l a a t t e e C C o o m m p p l l e e x x e e s s , [ [ ( ( C C u u2 2( ( R R C C O O2 2) )4 4) ) ] ] a a n n d d A A n n g g u u l l a a r r D D i i t t o o p p i i c c A A r r o o m m a a t t i i c c C C a a r r b b o o x x y y l l a a t t e e A A c c i i d d s s 4.1. Preamble The previous Chapter discussed the possibi lity of making these faceted polyhedra: small rhombihexahedron, small cubicuboctahe dra and octahemioctahedron. They are all structures that constitute the backbone of the ne tworks. It was our pre-design that if bdc is used instead of btc, discrete faceted polyhe dra could be made. However, zinc carboxylate interaction behaviors are so dive rse that the task of controll ing building units seems to be very difficult. It is therefore reasonable to sw itch to copper ion, a me tal ion that has better a controlled interaction patte rn with carboxylate groups. Dicoppertetracarboxylate complexes (SBUs), [(Cu2(RCO2)4)], have been well studied and there are over 436 entries for such structure in the Cambridge Structural Database (CSD) (CCDC 2004 Conquest Version 1.6). As illustrated in Appendix B, more than 40% of dimetaltetracarboxylate comple xes are built from Cu ion. Five compounds ( 7, 8, 9, 11, 12 ) summarized in this Chapter are built from copper square SBUs linked by bdc. Compound 10 is constructed from copper square SBU and 2,5thiophenedicarboxylic (tdc), another ditopic acid with an angle of ca. 144 separation between two carboxylate groups.

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74 4.2. Compound 7 -[(L)(S)Cu2(bdc)2]12 ( 7a and 7b )214 4.2.1. Experimental Section Synthesis of 7a [(L)(S)Cu2(bdc)2]12 (S = L = MeOH): In a typical reaction, a 10 mL methanolic solution of 1,3-benzened icarboxylic acid (0.033 mg; 0.199 mmol) is layered onto a 10.0 mL methanolic solution c ontaining copper nitrate hemipentahydrate (0.046 mg; 0.199 mmol) and nitrobenzene (3.0 mL; 30 mmol) and 2,6lutidine (0.30 mL; 3.4 mmol). Prismatic, blue-green, single cr ystals (0.10 x 0.10 x 0.30 mm) form within two weeks under ambient conditions. Yield: 10 mg, 18% based on Cu. Synthesis of 7b [(L)(S)Cu2(bdc)2]12 (L = Pyridine, S = MeOH): In a typical reaction, a 10 mL methanolic solution of copper nitrate hemipentahydrate (231 mg; 0.993 mmol) and 1,3-benzenedicarboxylic acid (166 mg; 0.999 mmol) is layered onto a 10 mL methanolic solution containing nitrobenzen e (2.0 mL; 19 mmol) and pyridine (0.23 mL; 2.8 mmol). Prismatic, blue-green, single cr ystals (0.15 x 0.15 x 0.10 mm) formed within hours under ambient conditions. Yield: 24 mg, 8.5% based on Cu. The thermal stabilities of 7a and 7b are consistent with their structures and molecular components. Crystals of 7a and 7b appear stable indefinitely when in contact with mother liquor. Weight loss of 36.9 and 38.3 %, respectively, corresponding to the loss of guest molecules occur when heated at the temperature of 100C. The samples do not remain as single crystals when heated. Loss of coordinated molecules occur at higher temperatures (300C). Eleven solv ents were used to check compound 7’ s solubility: Chloroform; Benzene; THF; DMSO; DMF, Acetone; EtOH, MeOH; 2-propanol, Pyrdine and Nitrobenzene. It was found that compound 7 was slightly soluble only in nitrobenzene.

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75 Selected crystallographic parameters of 7a and 7b are presented in Table 4.1 Complete crystallographic data for compound 7a and 7b can be found in Appendix A12 and A13. Table 4.1. Selected crystallogr aphic parameters for 7a and 7b Crystal system Space group (#) a () b () c () alpha () beta () gamma () V (3) 7a Cubic Im-3m (229) 27.6895(17) 27.6895(17) 27.6895(17) 90 90 90 21230(2) 7b Triclinic P-1 (2) 26.202(9) 27.756(10) 28.407(10) 92.583(5) 96.393(5) 92.643(5) 20483(12) 4.2.2. Structure elucidation Two crystalline phases that contain 7 were isolated: a cubic ( 7a ) and a triclinc ( 7b ) phase. The crystal structure of 7 is illustrated in Figure 4.1 and reveals that it can be described as being composed of vertex li nked molecular squares (green) that selfassemble into small rhombihexahedra This is a rare example, in that, its structure is known before it is actually made. 7a contains MeOH ligands at the both sides of axial directions of dimetal tetracarboxylate and 7b contains pyridine liga nds that are axially bonded to the metal ions that lie at the exte rior surface and MeOH ligands at the interior surface metal binding sites. The internal cavit ies for both of them have a volume of ca. 1nm3 that is easily large enough to encapsulate C60. They have molecular volume of >10nm3 and molecular weight of 6.49 and 6.80 kDa, respectively.

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76 In compound 7a there are two independent copp er ions, two independent oxygen atoms, five independent carbon atoms and two MeOH molecules. They generate the whole 12 dicopper tetracarboxylat e SBU and 24 bdc ligands to finish the spherical structure by symmetry operation. The Cu-Cu dist ance is 2.604(2) . Cu-O distances at equatorial directions are 1.959( 5) and 1.952(5) . Cu-O distan ces at axial directions are 2.164(11) and 2.165(13) . These numbers fall in the expected range (A CSD database statistic study of all thes e bond ranges is illustrated in Appendix C). In compound 7b there are 24 independent copper ions, 24 inde pendent bdc, 12 independent pyridine and 12 independent MeOH molecules. Guest mol ecules can not be recognized in both 7a and 7b due to disorder. Figure 4.1. Molecular, space filling models and topology of small rhombihexahedra in compound 7

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77 ________________________________________________________________________ ________________________________________________________________________ Figure 4.2. Body-center cubic packing of small rhombihexahedra in 7a (a) and 7b (b) (a) (b)

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78 In both compound 7a and 7b, small rhombihexahedra adopts a body-center cubic packing style in three-dimension as illustrate d in Figure 4.2. Each ball is located in the middle of eight balls of adjacent layers. There are no direct interactio ns between the balls in the same layer. Direct connection of the Cu-Cu middl e point of square SBU generates a cuboctahedron, an Archimedean solid. Figure 4.3 illustrates the new topology of this spherical architecture found in Compound 7 This new view illustrates that the structure is actually defined by 4-connected SBU nodes. In this situation, all the windows are open and edges are defined by bdc ligands. Compar ed to the first topology, this new topology omits the information of 120 arrangemen t of two carboxylate groups in bdc ligands, which is crucial to the design purpose. ________________________________________________________________________ (a) Perspective view (b) Down from square channel (c) Down from a node Figure 4.3. Schematic illustration of Compound 7 of SBU connectivity

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79 4.3 Compound 8 -{[Cu2(bdc)2(py)2]4}n 215 4.3.1 Experimental Section Green crystals of 8 were obtained from slow diffu sion of an ethanolic solution (4.0 mL) of 1,3-benzenedicarboxylic acid (166 mg, 0.999 mmol) and pyridine (0.240 mL, 2.97 mmol) into an aqueous solution (4.0 mL) of copper nitrate he mipentahydrate (233 mg, 1.00 mmol). Crystals formed within days in 40% yield (153 mg) based on Cu. The crystals are thermally stable up to 100 C, after which the TG curve shows a mass loss of about 19% between 100 and 250 C. Further heating leads to decomposition above 300C. The most intense peaks observed in the X-ray powder diffraction (XPD) patterns from the bulk sample are consistent with t hose calculated from si ngle-crystal diffraction data. Selected crystallographic parameters are presented in Table 4.2. Complete crystallographic data for compound 8 can be found in Appendix A14. Table 4.2. Selected crysta llographic parameters for 8 Crystal class Space group (#) a () = b () c () V (3) Tetragonal P4/ncc (126) 18.7912(8) 16.8886(10) 5963.5(8) 4.3.2. Structure elucidation The compound 8 is crystallized in tetragona l symmetry. Like that of compound 7 its structure is also constructed from the linkage of dicopper te tracarboxylate SBUs by bdc ligands, which, in this case, a layer stru cture is formed. The difference between these

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80 two compounds is the arrangement of the bdc around the SBU as illustrated in Figure 4.4. In Compound 7 all these four bdc molecules are at the same side of the dicopper core (Figure 4.4a). However, in compound 8 they possess a style of 1,2-up and 3,4-down mode (Figure 4.4b). As a result, infinite co ordination polymers are generated instead of finite polyhedron. ________________________________________________________________________ ________________________________________________________________________ Figure 4.4. Two differen t arrangements of bdc molecules ar ound the dicopper center in (a) Compound 7 and (b) compound 8 In this compound, there is one copper atom, one bdc and one pyridine molecule in every asymmetry unit with the distan ce of Cu-O [1.9417(19), 1.950(2), 1.996(2), 2.006(2) ], Cu-N 2.158(2) , Cu-Cu 2.6676(7) . Two different types of connectivity of four SBUs are found as illustrated in Fi gure 4.5. One is all bdc molecules are up which constructed into a bowl shape c ontainer. The other is the connection of four SBUs into a structure with four bdc taking arrangeme nt of 1,3-up, 2,4-down mode. We named these big building units as nano-sized SBUs (nSBUs). For the bowl shape structure, each bowl ha s an outer diameter of 0.94 nm, a depth (as measured by the perpendicular distance from the center of the base to mid-point of a

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81 line joining the top hydrogen atoms on opposite bdc moieties) of 0.84 nm and a solventaccessible volume of 0.518 nm3. __________________________________________________________________________________________ Bowl-shape nSBU -top view ________________________________________________________________________ Bowl-shape nSBU – side view ________________________________________________________________________ 1,3 alternative nSBU -top view ________________________________________________________________________ Figure 4.5. Space filling and ball and stick models of two different types of nano-sized SBUs in Compound 8

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82 The layers pack is illustrated in Figure 4.6(b), giving rise to a channel between adjacent bowls. The channels are hou r-glass shaped with a cavity of maximum dimensions of ca. 0.90 x 0.90 x 0.65 nm. Between these cavities the channel narrows to an opening of ca 0.15 x 0.15 nm which restricts the m ovement of big guest molecules through the channel. The distance be tween guest molecules is 0.81 nm. ________________________________________________________________________ ________________________________________________________________________ Figure 4.6. (a) Space-filling diagram of the crystal structure of 8. (Guest molecules have been omitted for clarity). (b) Profile of the hour-gla ss shaped channels between adjacent bowls. The shaded area is the empty volume; guest molecules are located in the widest areas of the channels. (c)Packing view of the layers (a) (b) (c)

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83 Figure 4.8 illustrates the network topology of 8 Connection of the Cu-Cu middle points of SBUs results in a (4, 4) square gr ids sheet, which is constructed from square nodes. These sheets stack each other with AAA mode (Figure 4.6(c)). The dimensions of the grids are 0.941 x 0.941 nm2. The total volume of both ty pes of cavities represents ca. 23% of the volume of the unit cell. ________________________________________________________________________ ________________________________________________________________________ Figure 4.7. Schematic illustration of the networ k observed in compound 8 (a) top view (axial pyridines are omitted for clarity) (b) side view (molecules are omitted). 4.4. Compound 9 -{[Cu2(bdc)2(4-pic)2]4 4( oDichlorobenzene)}n 216 4.4.1. Experimental Section In a typical condition, green crystals of 9 were obtained from the slow diffusion of a methanolic solution (7.0 mL) of 1,3-benzenedicarboxylic acid (166mg, 0.999 mmol) and 4-picoline (4-pic) (0.30 mL 3.1 mmol) into a methanolic solution (7.0 mL) of copper nitrate hemipentahydrate (233 mg, 1.00 mmol) containing 5 mL of o-dichlorobenzene. Crystals formed after 6 months in 50% yield (197 mg). The crystals are thermally stable up to 200 C after which the TG curve show s a weight loss of 58% between 250 and 300

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84 C and a second weight loss of 16% between 350 and 400 C. Further heating of the sample results in decomposition. Selected crystallographic parameters are presented in Table 4.3. Complete crystallographic data for compound 9 can be found in Appendix A15. Table 4.3. Selected crysta llographic parameters for 9 Crystal system Space group (#) a () b () c () beta () V (3) Monoclinic Cc (9) 19.5148(14) 12.7678(9) 14.3466(10) 114.1330(10) 3262.2(4) 4.4.2 Structure elucidation Compound 9 is constructed from dicopper te tracarboxylate SBUs that are linked by bdc ligands. Its 2-D structur e is different from compound 8 The difference is that compounds 8 and 9 have different styles of arrangement of the tetra-SBUs. For compound 9 {[Cu2(bdc)2(4-pic)2]4}n, the nSBU adopts the 1,2-up, 3,4-down configuration (Figure 4.8) and contains an o-dichlorobenzene molecule in the resulting cavity (Figure 4.9). Another difference in compound 9 is that the two carboxylate (CO2) groups rotate to each other with ca. 40. This spatial arra ngement of bdc molecules enables compound 9 retaining 2-D structure while adopting a 1,2-up, 3,4-down conformation of tetrakis -SBUs. The crystal is in m onoclinic symmetry Cc space group. The non-center symmetry is caused by the polar arrangement of o-di chlorobenzene guest molecules.

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85 ________________________________________________________________________ ________________________________________________________________________ Figure 4.8. Space filling and ball and stick models of 1,2 alternative nano-sized SBU in Compound 9 __________________________________________________________________________________________ ________________________________________________________________________ Figure 4.9. (a) Space filling model of one layer st ructure (b) One layer in ball-stick model with odichlorobenzene solvents in spac e-filling model. Each cavity contains one guest molecule. Note: guests are in polar arrangement In compound 9 there are two copper atoms, tw o bdc, two 4-picoline and one odichlorobenzene guest molecule in every as ymmetry unit with the distance of Cu1-O [1.958(3), 1.966(3), 1.973(3), 1.996(4) ], C u2-O [1.965(4), 1.974(4), 2.005(3), 1.965(4) ] and Cu-N 2.155(4) and 2.145( 4) , Cu-Cu 2.6683(6) . (a) (b)

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86 The nSBUs self-assemble into 2-D corrugate d square grids that propagate in the YZ-plane and stack along the X axis in an ABCDABCD fash ion (Figure 4.10) with an interlayer separation of 0.98 nm. The dime nsions of the grids measure 0.960 X 0.960 nm2 (distance from Cu-Cu midpoint of adjacen t SBU units in the nSBU). The unit cell contains no residual solvent accessible area. However, the potential solvent accessible area upon removal of th e guest is 25.9%. ________________________________________________________________________ ________________________________________________________________________ Figure 4.10 Packing view of compound 9 (4-picoline and guest molecules are omitted for clarity) 4.5. Compound 10 -{[Cu2(tdc)2(MeOH)2]44Naphthalene-8MeOH}n 216 4.5.1. Experimental Section In a typical reaction, green crystals of 10 were obtained from the slow diffusion of a methanolic solution (10.0 mL) of coppe r nitrate hemipent ahydrate (233 mg, 1.00 mmol), 2,5-thiophenedicarboxylic (tdc) (172m g, 0.999 mmol) and na phthalene (256 mg,

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87 2.03 mmol) into a methanolic solution containing pyridine (0.20 mL, 2.5 mmol), naphthalene (256 mg, 2.03 mmol), and nitrobenzene (3.0 mL, 30 mmol). Crystals formed within days in a 12% yield (41 mg). TG anal ysis illustrates a weight loss of 12% between 95 and 105 C followed by another weight loss of 10% between 120 and 170 C. The framework appears to be stable up to 250 C above which the TG curve shows a weight loss of 50% between 290 and 310 C. Further heating of the sample results in its decomposition. The most intense peaks obser ved in the X-ray powder diffraction (XPD) patterns from the bulk sample are consistent with those calculated from single-crystal diffraction data. Selected crystallographic parameters are presented in Table 4.4. Complete crystallographic data for compound 10 can be found in Appendix A16. Table 4.4. Selected crysta llographic parameters for 10 Crystal system Space group (#) a () b () c () beta () V (3) Monoclinic C2/c (15) 15.637(4) 15.430(4) 13.332(3) 116.692(4) 2874.1(13) 4.5.2. Structure elucidation The structure of compound 10 is similar to that of compound 9 except tds is used to replace bdc. The [Cu2(tdc)2(MeOH)2]4 nSBU adopts the 1,2-al ternate conformation (Figure 4.11) and contains one naphthalene and two MeOH molecule s in the resulting cavity (Figure 4.12).

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88 ________________________________________________________________________ ________________________________________________________________________ Figure 4.11. Space filling and ball and stick mode ls of 1,2 alternative nano-sized SBU in Compound 10 ________________________________________________________________________ Figure 4.12. (a) Ball and stick diagram of the lay er structure of 10. Each cavity contains one naphthalene and two MeOH guest molecules. (b) Pa cking view of the stacking of layers in 10 There is one copper atom, one tdc, a ha lf guest naphthalene and two MeOH (one is coordinated with dicopper SBU at axial direction, another is a guest) molecules in (a) (b)

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89 every asymmetry unit with the distances of Cu-O equatorial [1.952(4) 1.962(4) 1.964(4) 1.969(4) ], Cu-O axial 2.146(4) , and Cu-Cu 2.6073(15) . Compound 10 can also be described as a corr ugated grid. The grids propagate in the YZ plane and stack along the X axis in ABAB fashion, so that every third layer repeats. The interlayer separation between two adjacent sheets is 0.78 nm. Each nSBU contains naphthalene molecule and has tw o methanol molecules that H-bond to the coordinated methanol molecules in the apical positions (O…O 2.705(7) ). The dimensions of the grids are 1.02 x 1.02 nm2 (distance from the Cu-Cu midpoint of adjacent SBU units in the nSBU). There is no residual solvent accessible area in the unit cell, however, the potential solvent area, upon removal of the guests, is 45.8% 4.6. Compound 11 (Kagome Lattice) -{[L2Cu2(bdc)2]3}n ( 11a and 11b )45 4.6.1. Experimental Section Synthesis of 11a {[L2Cu2(bdc)2]3}n (L= pyridine): In a typical reaction, a 10 mL ethanolic solution of copper nitrate hemi pentahydrate (231 mg; 0.993 mmol) is layered onto a 10 mL ethanolic solu tion containing 1,3-benzenedi carboxylic acid (166 mg; 0.999 mmol) and pyridine (0.23 mL; 2.8 mmol). Slow diffusion of ethanol ic copper(II) nitrate into a solution of 1,3-bdc and pyridine in et hanol in the presence of an appropriate template (nitrobenzene, 1,2-dichlorobenzene or naphthalene) affords prismatic blue-green crystals of [(L2Cu2(bdc)2)3]n, 11a crystalline hexagonal plates (0.15 x 0.15 x 0.05 mm3) formed within hours under ambient conditions. Yield 36 mg about 10% based on Cu. Synthesis of 11b {[L2Cu2(bdc)2]3}n (L= isoquinoline): a 10 mL ethanolic solution of copper nitrate hemipentahydrat e (233 mg; 1.00 mmol) is layered onto a 10

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90 mL ethanolic solution containing 1,3-ben zenedicarboxylic acid (166 mg; 0.999 mmol), nitrobenzene (2.0 mL; 19 mmol) and 0.3ml of isoquinoline (2.60 mmol). Prismatic bluegreen crystals of [(L2Cu2(bdc)2)3]n, 11b crystalline hexagonal plates (0.1 x 0.1 x 0.02 mm3) formed within hours under ambient cond itions. Yield 20 mg 5% based on Cu. Thermal analysis (TGA/DSC) suggests that the included solven t and the pyridine ligands can be removed at ca. 200C, and that th e desolvated lattice is thermally stable to temperatures in excess of 300C. Around 27 %-30% guest weight loss was found before the framework collapsed. Selected crystallographic parameters of 11a and 11b are presented in Table 4.5 Complete crystallographic data for compound 11a and 11b can be found in Appendix A17 and A18. Table 4.5. Selected crystallogr aphic parameters for 11a and 11b Crystal class Space group (#) a () = b () c () V (3) 11a Trigonal P-3c1 (165) 18.6200(17) 19.8040(27) 5946.2(11) 11b Trigonal P-3 (147) 18.8573(12) 12.7135(12) 3915.2(5) 4.6.2. Structure elucidation Compound 11a is crystallized in trigonal high symmetry. All the metal ions and carboxylate groups are engaged in dimeta ltetracarboxylate complexes. The axial directions of each SBU are capped with two pyridines molecules. In this compound, one asymmetry unit contains one copper atom, one bdc and one pyridine. The distances

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91 between Cu-O are 1.960(3) 1.965(3) 1.966(3) 1.982(3) ; Cu-N 2.158(4) ; Cu-Cu 2.6639(10) . ________________________________________________________________________ Trigonal nano-SBU (top view) _______________________________________________________________________ Trigonal nano-SBU (side view) ________________________________________________________________________ Figure 4.13. Space filling and ball-stick mo dels of trigonal nSBU in Compound 11 The crystal structure of 11a (Figure 4.13) can be descri bed as the result of selfassembly of triangular nSBU’s to yield a nanoscale Kagom lattice. Cu dimers are positioned at the lattice points and are brid ged via the bdc ligands, thereby generating large hexagonal cavities within the layer. The bowl-shaped nSBU facilitates efficient packing when the bowls are eclipsed, which results in the eclips ing of the hexagonal

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92 cavities (0.91 nm effective diameter) and he xagonal channels of the same dimension. Disordered solvent and guest molecule s are located inside the channels. ________________________________________________________________________ ________________________________________________________________________ Figure 4.14. (a) Space-filling diagram of the crystal structure of 11. (Guest molecules have been omitted for clarity). (b) Packing view of the stacking of layers in 11a The layers are undulating due to the curvat ure imparted by the bdc moiety, have a 1.24 nm amplitude and overlap with adjacent layers by ca. 20 %. This overlap is mainly due to the interdigitation of axial pyridin e molecules. The distance between adjacent layers is 9.9 . These layers stack e ach other in a AAA fa shion. There are C-H… and … interactions betw een layers (the C… centroid distance is 3.762 and the (a) (b)

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93 centroid… centroid distance are 4.882 , shortest C… C distances are 3.644 and 3.870 , consistent with distances to be expected for such interactions). Compound 11b has the same fashion as 11a However, due to the change of the axial ligand, the axial directions of each SB U are capped with two two-fold disordered isoquinoline molecules. Thus, the distance betw een adjacent layers enlarges from 9.9 to 12.7 . In this compound, one asymmetry uni t contains one copper atom, one bdc and one isoquinoline molecules. The distances are: Cu-O, 1.973(6) 1.978(6), 1.980(6), and 1.982(6) ; Cu-N, 2.180(8) and 2.20 7(9) ; Cu-Cu 2.671(2) . ________________________________________________________________________ ________________________________________________________________________ Figure 4.15. Packing view of the stacking of layers in 11b There are some differences between 11a and 11b. Apparently the axial ligands are different which results in the di fference of interlayer distance s. Another difference is that in 11a two axial ligands (pyridine molecules) are not at the opposite positions of the dimetal center, which prevents the center symmetry. Thus each of the layers in 11a is in

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94 non-center symmetry. The bulky phase is in cen ter symmetry because adjacent layer with invert direction create center symmetry in between the two layers The same phenomena can also be observed in compound 8 11b is different in that center symmetry does exist because of the two-fold disorder of iosquinoline. Therefore, unlike 11b which the c value (unit cell) is exactly same as the interlayer distance, 11a has a c value that is exactly a doubled value of interlayer distance. Figure 4.16 illustrates the network topology by the connecting of middle points of Cu-Cu bond in SBUs. The resulted Kagome latti ce is of interest in magnetic purpose. Actually, this compound shows a magnetic hy steresis loop at the temperature 5K,45,217 which is different from compound 8 It is interesting to see th at different topologies that are built from the same building units could resu lt in significant differences in properties. ________________________________________________________________________ ________________________________________________________________________ Figure 4.16. Schematic illustration of the network observed in co mpound 11 (a) top view (axial pyridines are omitted for clarity) (b) side view (molecules are omitted). (b) (a)

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95 4.7. Compound 12 -[Cu2(bdc)2(L)2]n (USF-1)218 4.7.1. Experimental Section In a typical condition, green crystals of 12 were obtained from the slow diffusion of a methanolic solution (7.0 mL) of 1,3-benzenedicarboxylic acid (166mg, 0.999 mmol) and Quinoline (0.30 mL, 2.5 mmol) into a metha nolic solution (7.0 mL) of copper nitrate hemipentahydrate (233 mg, 1.00 mmol) containing 3.0 mL of nitrobenzene. Crystals formed after one week in a 10% yield (35 mg ). The crystals are thermally stable up to 280 C after which the TG curve shows a we ight loss of 46% between 280 and 300 C and a second weight loss of 29% between 300 and 400 C. Further heating of the sample results in decomposition. The most intense peaks observed in the X-ray powder diffraction (XPD) patterns from the bulk sample are consistent with those calculated from single-crystal diffraction data. Selected crystallographic parameters are presented in Table 4.6. Complete crystallographic data for compound 12 can be found in Appendix A19. Table 4.6. Selected crysta llographic parameters for 12 Crystal system Space group (#) a () = b () c () V (3) Rhombohedral R-3c (167) 30.337(2) 18.380(2) 14649(2) 4.7.2. Structure elucidation The crystal structure of 12 [{Cu2(bdc)2(L)2}n] (L = quinoline) is illustrated in Figures 4.17 and 4.18. It is another example that crystal structure is composed of dimetal

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96 tetracarboxylate paddlewheel clusters, sec ondary building units (SBUs), bridged by bdc moieties. In compound 7, 8, 9 and 11 the two carboxylate groups in every bdc molecule are nearly in the same plane of the benzen e ring of bdc (See Figure 4.17a). However, the two independent isoph thalates in compound 12 have torsion angles of 25.3 and 16.5 for both carboxylates, respectively. This leads to the isophthalate imposing an out-of-plane torsional strain of 50.6 and 33.0 between vertex-connected molecular squares. This change results in a 3-D arrangement of four connected dicopper SBU nodes (Figure 4.17b). Since all the other reacti on conditions are same, the us ing of quinoline is the only reason that initiates this change. ________________________________________________________________________ ________________________________________________________________________ Figure 4.17. (a) Crystal structure of 12; (b) bdc mo lecule nearly at the sa me plane in compounds 7, 8, and 11; (c) Carboxylate groups in bdc mo lecule deviate themselves from benzene ring in compound 12 (a) (b) (c)

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97 4.7.3. Network topology To our knowledge, compound 12 represents the first example of a class of compounds that possess a new 65.8 topology, which is termed as USF-1. Figure 4.18a illustrates the topology of USF-1 (the conn ectivity of SBUs by connecting the middle point of Cu-Cu bond) of compound 12 It has the same circuit symbol as CdSO4 topology, another 4-connected 3-D net (Figur e 4.18b). However, their structures are definitely different. Viewing from the t op, the topology of USF-1 has three sets of paralleled grids with a 60 rotation to each other and cross linked by 4-connected nodes while the topology of CdSO4 has only two sets of sheets with 90 rotation to each other. The further study of Schlaft notation reveal s the difference between the two networks. USF-1 possesses (62, 62, 63, 63, 62, ) while CdSO4 has (62, 62, 62, 62, 62, ). ________________________________________________________________________ USF-1 CdSO4 Figure 4.18. Schematic illustration of the topology of USF-1 and CdSO4

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98 4.8. Discussion and Conclusion Five different topologies ar e described in this Chapter. They can be obtained from self-assembly of the same starting materials (c opper (II) and bdc), the same ratio of Cu : bdc at 1 : 1 and constructed from the same building blocks (square SBUs). Therefore, these five networks can be regarded as s upramolecular isomers. Two other conformations that are not included in this Chapter were also obtained in Zaworotko’s research group. One of them is a spherical nano structure, A .214 The other is a 2-D coordination polymer with partial cone arrangement of tetra-SBUs.216 Further studies illustrated that some of these structures can su rvive by variation of metal ions. For example, zinc(II) analogies of compound 8 9, 11 and 12 have been obtained.88,218,219 A cobalt(II) analogy of compound 12 was also synthesized.218 ________________________________________________________________________ 7 8 9 11 12 Figure 4.19. Five structures with different topol ogies that are constructed from square SBU and bdc O OH OH O +

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99 Compounds 7a and 7b represent new examples of giant discrete architectures possessing internal cavities with a topology related with Platonic and Archimedean solids. Yaghi’s research group220 reported a similar structure at the same time. Other related compounds, including hydrogen bonding structures (snub cube221 and great rhombicubeoctahedron222) and coordination bonding st ructures (tetrahedron,223-225 hexahedron,226 cuboctahedron,120,227 dodecahedron228 and rhombicuboctahedron,212,213) were reported recently. An isomer of compound 7 A [P63/m, a = b = 28.6458(19) , C = 28.1649(26) , V = 20015.2 3] is also in ball-shape. It is constructed from the same number of Cu ions and bdc molecules as that of compound 7 but in different 3-D structures. The connectivity of SBUs of compounds 7 and A are illustrated in Figure 4.20. There are three differences between th ese two compounds. 1). Compound 7 is in center symmetry and compound A is not. 2). Compound 7 has both 4-fold and 3-fold axis and compound A only has 3-fold axis. 3). Compound 7 possesses four hexagons th at equally divide the structure into two parts while compound A only has one. An important similarity between the structures is that both structures can be describe d as having a center hexagon composed of six SBUs around the equator with triangular nSBU at both ends. This can be observed from the skeleton graphs of these two compounds in Figure 4.20. The fundamental difference in the connectivity of these two structures is : the triangular nSBU are staggered in compound 7 ( with one square and one triangle share center hexagon edges) and eclipsed in compound A (with square and square or triangle and triangle share center hexagon edges).

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100 ________________________________________________________________________ ________________________________________________________________________ Figure 4.20. Connectivity of SBUs in compound 7 and compound A One of the structure features of bdc is that it possesses planar non-center symmetry. So, it has two different orientations (up and down) when it binds the dicopper center. Figure 4.21 illustrates th e two different ways of connectivity of molecular square. Note here, in Figure 4.21 (a) bdc molecules poi nt down at the end side of square SBUs, and in Figure 4.21 (b) bdc molecules point up. These two conformations direct the extension of SBUs into fini te or infinite structures. Compound 7 Compound A

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101 ________________________________________________________________________ ________________________________________________________________________ Figure 4.21. Two different arrangemen ts of molecular squares bridge d by bdc (a) in compound 7; (b) in compounds 8, 9 and 11 For the dicarboxylic acids, there are two a dditional concerns for the arrangements of the two-carboxylate groups (See Figure 4.22). One is the angle ( ) to the middle of the link; the other is the rotation angle ( ) of the planes of the carboxylates to each other. In our case, two carboxylates are in 120 separation around the ce nter of benzene ring. They are all in the same plane as the benzene ring in 7, 8, and 11 except in 9 12 in which the two carboxylate groups rotate to each other. Similar phenomena have been observed in which CdSO4 and NbO topologies are revealed.192,195 The angle ( ) at 120 is critical for the design of discrete structure. However, it is not necessary for 2-D and 3-D structures. Actually, tdc (with at ca. 144) has been used to bu ild compounds with the same topologies as 9 and 11 (a) (b)

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102 Figure 4.22. Schematic illustration of the permutation of two carbox ylate groups in dicarboxylic acid Built from tetra-SBU, compounds 8 and 9 remind us of the structure of calix[4]arene. There are four possible atropisome rs of calix[4]arenes that were designated by Gutsche229,230 as the cone, partial cone, 1,2-altern ate, and 1,3-alternate, all illustrated in Figure 4.23. The nomenclature refers to the orientation of the aren e rings with respect to one another. In the cone conformation, all arenes point up a nd form a cone-like structure, whereas in the partial cone three arenes point up and one points down. Interestingly, the structures of the tetra-SBU could have four types of conformation isomers which are closely related with those of calix[4]arene. Three of them are found in compounds 8 (cone and 1,3-alternate) and 9 (1,2-alternate). OH O O OH

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103 Figure 4.23. Schematic illustration of four atropisomers of a calix [4]arene: (a) cone, (b) partial cone, (c) 1,2-alternate, and (d) 1,3-alternate. Synthetic conditions play critical roles in the formation of supramolecular isomers of compounds 7, 8, 9, 11 and 12 1. Solvent effect Solvents are selected according to thei r solubility of metal ions and organic ligands. Normally they are mediums of reactions and many times solvent molecules occupy the void space created by coordination ne tworks. Sometimes, solvents also play an important role in the formation of speci fic crystalline phases. For example, compound 11 is synthesized from the EtOH solution. Compound 7 is the preferred crystalline product when MeOH is used. 2. Template effect Nitrobenzene and o-dichlor obenzene are normally used as templates. These aromatic solvents may have a role in stabilizing SBUs or nano SBUs.

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104 3. Stoichiometry effect Stoichiometry is also an important fact or. For example, an overdose of pyridine could introduce a strong basi c condition which favors mono metal fashion and destroys the SBUs. Normally the ration of meta l ion: bdc : base is 1: 2 : 3. Axial ligands also have an important role in the formation of network topologies of 9 and 12 Five different bases are used in this work: 2,6-lutidine, 4picoline, pyridine, quinoline and isoquinoline. Thei r functions are two-fold. One is to de-proton the carboxylic acid. The other is to act as m ono coordinated ligands capped on the axial directions of SBUs. Because the bottom area of the cone conformation has limited space, the using of a large-size ligand may frustrat e the cone conformation and favor others. Therefore, it can also change the conn ectivity of SBUs as seen in compound 12 Finally, there exists structure relations hip between compound 6 and compounds 7 8 and 11 Compound 6 is the “mother” structure, which contains 7, 8 and 11 inside its network as illustrated in Figure 4.24. ________________________________________________________________________ Figure 4.24. Illustration of extraction of 2-D networks (without axial ligands) in compounds 8 and 11 from the 3-D network of compound 6

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105 The successfully syntheses of 7, 8 and 11 illustrated the feasibility of design of these “daughter” structures based on the information given by “mother” structure (compound 6 ). The existence of compounds 9 and 12 indicate the flexibility of other possible structures since the re duction of dimension of the ligand may give more freedom to the selection of packing styles, which coul d be generated by the self-assembly of these building units. In conclusion, five supramolecular isomer s were synthesized from the Cu and bdc system by changing synthetic conditions. The lack of inversion center in bdc ligand creates additional structure di versity of possible networks. In return, these structures provide important information that is cri tical for further research. They are also potentially useful substances, since most of them are nanoporous materials.

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106 C C h h a a p p t t e e r r 5 5 S S e e l l f f A A s s s s e e m m b b l l e e d d S S u u p p r r a a m m o o l l e e c c u u l l e e s s B B a a s s e e d d u u p p o o n n L L i i n n e e a a r r D D i i m m e e t t a a l l T T e e t t r r a a c c a a r r b b o o x x y y l l a a t t e e C C o o m m p p l l e e x x e e s s , [ [ ( ( M M2 2( ( R R C C O O2 2) )4 4) ) ] ] 5.1. Preamble Chapter 3 and 4 have illustrated how dimetaltetracarboyxlates as square secondary building units (SBUs), could genera te network structures by the extension of the equatorial sites of the SBU. However, the axial sites are also available for functionalization and make such SBUs suitable for use as linear spacer moieties as illustrated in Figure 5.1. In fact, the first effort to connect discrete SBU at axial direction was reported two decades ago185,231 and after, multidentate amines had already been exploited to connect the axial sites of th ese SBUs to form coordination polymers. Although some of these works focus on the magnetism232-234 and sorption purposes,235,236 generally, all these researches are carried on the interest of building infinite structures.237240 We think that the research in axial direc tions needs to be furt her addressed because there are still many questions that to our knowledge remain virtually unanswered in the context of self-assembly of s upramolecular species, in partic ular function materials based research.

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107 Figure 5.1. The M2( -O2CR)4 moiety functions as linear spacer This moiety has been prepared for a wide range of transition metals and can be readily functionalized at either the equatorial or axial positions. This Chapter’s study focuses on the de sign and syntheses of coordination polymers based upon linear spacer, di coppertetracarboxylate complexes [Cu2(RCO2)4], and organic ligands. Figure 5.2 illustrates organic ligands that have been us ed in this work. Linear ditopic ligands bpeta are selected to build hos t/guest systems that may have the ability to uptake aromatic guests. Melamine and HMTA are selected to build high dimensional structures. Melamine has three identical aromatic nitrogen atoms in a triangle arrangement and there have been very few re ports concerning its use as a coordination ligand,241,242 none of which are coordination polymer s. Hexamethyltetramine, HMTA, is another candidate. Although it pos sesses four identical nitrogen atoms in Td symmetry, however, HMTA is well known for its vari able coordination number (See Figure 5.3).238,243-247

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108 (a) (b) (c) N N N N Figure 5.2. Organic ligands that a re used to connect linear SBUs Figure 5.3. HMTA molecular can be projected as a tetrahedral node, angler, pseudo trigonal or tetragonal geometries will be generated when HMTA uses its 2, 3, or 4 nitrogen atoms respectively. Eight monocarboxylic acids have been used: formic acid, propionic acid, isobutyric acid, t-Butyric acid, cyclohexanecarbo xylic acid, benzoate acid, 4-anisic acid and 4-nitrobenzoic acid. These carboxylic acids terminate the paddlewheel SBUs at equatorial directions. Ditopic Ligands N N Trigonal & Tetrahedral Ligands N N N N H2 NH2 NH2 N N N N

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109 Figure 5.4 illustrates the possi ble topologies of the resu lted coordination polymers based upon the geometric nature of organi c ligands and linear SBU spacers. Ditopic ligands (linear or angular) will result in stra ight line, zigzag chain, discrete or helix structures. Trigonal ligands will generate networ ks with (n, 3) topologies, such as (6, 3) or (10,3)-a. Diamondoid topology is expected if a tetra gonal node is present. Figure 5.4. A schematic representa tion of the possible topologies that are based upon the symmetry of the ligands used in this study.

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110 5.2. Compound 13 -[Cu2(C6H5CO2)4](bpeta)xGuest ( 13a-13g ) 5.2.1. Experimental Section The syntheses of compounds [Cu2(C6H5CO2)4](bpeta)xGuest ( 13 ) are in similar procedures with a yield of about 20~40%. A typical met hod is described below. A 10.0 mL methanol solution of 1,2-bis (4-pyridyl)ethane (0.128 g, 1.00 mmol) was carefully layered onto a 10.0 mL methano l/aromatic (1:1) soluti on of copper nitrate hemipentahydrate (0.232 g, 0.999 mmol) and so dium benzoate (0.288 g, 2.00 mmol). The host compound ( 13a ) was obtained in a condition of no aromatic guest or naphthalene or biphenyl as guest molecule s. Green crystals [Cu2(C6H5CO2)4](bpeta)xGuest ( 13a-13g) were obtained after one week. [Guest molecules: no guest ( 13a ), Anisole ( 13b, x = 1), toluene ( 13c, x = 1), p-Xylene ( 3d, x = 1), nitrobenzene benzene ( 13e, x = 2), 1,2Dichlorobenzene ( 13f x = 2 ) or Benzene ( 13g x = 1.5)]. The most intense peaks observed in the X-ray powder diffraction (XPD) patterns from the bulk sample are consistent with those calculated fr om single-crystal diffraction data. Selected crystallographic parameters of 13a-13g are presented in Table 5.1 Complete crystallographic data for compound 13a-13g can be found in Appendix A20A26.

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111Table 5.1. Selected crystallo graphic parameters for 13a-g Crystal system Space group (#) a () b () c () alpha () beta () gamma () V (3) 13a Monoclinic C2/m (12) 10.458(2) 18.489(4) 9.993(2) 90 104.753(4) 90 1868.6(7) 13b Triclinic P-1 (2) 10.4099(8) 10.9301(8) 19.8827(15) 74.7720(10) 75.5240(10) 76.9480(10) 2082.3(3) 13c Triclinic P-1 (2) 9.943(2) 10.216(2) 11.118(3) 99.743(4) 97.904(5) 107.601(4) 1039.3(4) 13d Triclinic P-1 (2) 9.987(2) 10.085(2) 11.104(2) 97.770(3) 98.563(3) 107.883(3) 1032.8(4) Crystal system Space group (#) a () b () c () alpha () beta () gamma () V (3) 13e Triclinic P-1 (2) 8.1454(12) 12.1913(17) 12.3830(18) 78.398(2) 88.018(2) 75.468(2) 1165.8(3) 13f Triclinic P-1 (2) 8.4456(11) 11.9794(16) 12.6532(17) 74.784(2) 86.305(2) 76.146(2) 1199.3(3) 13g Triclinic P-1 (2) 9.9683(12) 10.4761(13) 22.098(3) 100.970(2) 94.743(2) 105.011(2) 2166.9(5) Thermal analyses The TGA data of apohost compound illustrates that it is stable up to 250 C followed by a one step 67% weight loss (250-300 C) corresponding to the total decompose of coordination polymer. All th e TGA data of the host/guest compounds show that guests can be removed at a temperature below 200 C followed by the

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112 decomposition of bulk phase (250-300 C). A summary of TGA data of peak temperatures that guest molecules were remove d is illustrated in Table 5.2. For 13b-13d temperatures higher than their boiling points were found. For 13e and 13f temperatures lower than their boiling points were found. For 13g, a very broad temperatur e range with the peak temperature of 108 C was found. Table 5.2. TGA data summary of the percen tage and temperature upon removal of guest molecules in compounds 13b-13g Compound Guest TGA Percentage of weight loss and peak temperature Calculated weight loss and Boiling point of the guests 13b Anisole 11.8% 173 C 11.9% 154 C 13c Toluene 9.41% 138 C 10.3% 110 C 13d P-Xylene 12.2% 181 C 11.7%, 138 C 13e Nitrobenzene 20.3% 111 C 23.5%, 211 C 13f oDichlorobenzene 15.9% 90 C 26.7%, 180 C 13g Benzene 11.5% 108 C 12.8%, 80 C 5.2.2. Structure Elucidation: Host Structure [Cu2(O2CC6H5)4](bpeta) -13a : Single crystal X-ray diffract ion reveals that compound 13a consists of 1-D chain structures that are packed each other in paralle l. Each chain is composed by an alternative arrangement of bicoppertetrabenzoate co mplex and linear ditopic ligand bpeta. Bicoppertetrabenzoate complex is a paddle-wheel like structure with the distance of each paddle about 6.8 (Figure 5.5a). There is on e copper SBU and one bpeta molecule in every asymmetry unit. Copper atoms are under normal conditions with the distance of Cu-O at 1.970(4), 1.970(4), 1.974(6) and 1.974(5) , Cu-Cu at 2.6557(16) and Cu-N at

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113 2.171(6) . The angle of Cu-Cu-N is 171.6. The bpeta molecules are flat and located in the middle position of two paddle wheels with the ideal angle of 45. (Figure 5.5b) ________________________________________________________________________ ________________________________________________________________________ 6.8 (a) (b) (c) (d) 45

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114 ________________________________________________________________________ ________________________________________________________________________ Figure 5.5. (a) A view of the 1D chain composed of bimetal liner spacer and bipyethane; (b) Tope view of the chain (c) Packing view of chains into a layer structure by interdigitation and C-H interactions; (d) Tope view of the layer (the ch annel direction is marked by a blue arrow) (e) A view of two adjacent layers stack each other by interactions. These 1-D chain polymers were cl osely packed each other along ac plane with interdigitation to be a layer st ructure. (Figure 5.5c) Weak C-H interactions (shortest C-C distance 3.94 ) are found between adj acent chains. The distance between the adjacent chains in the layer is 6.5 . ch annels are found running through the adjacent chains in a direction along b axis (Figure 5.5d). Thus, period ic “groove-like” channels are distributed in the same layer along c axis. Adjacent layers stack each other only by a slight move a /2 (5.2 ) in the direction of a axis. Thus, these channels are se lf-filled by adjacent layers along the b axis (Figure 5.5e). Additional interactions (shortest C-C di stance 3.63 ) were found between the benzoate groups. The distance betw een adjacent layers is 9.2 . ( e )

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115 Host/guest compounds: The structures of host/guest compounds ha ve a similar layer packing style except that instead of direct inter action of adjacent layers, the aromatic solvent molecules are held in between and located inside the cha nnels. The distances of layers are therefore expanded. Three different types of host/ guest styles are defined as Type I ( 13b-13d ), Type II ( 13e and 13f ) and Type III ( 13g ), corresponding to the ratio of SBU to solvent molecular of 1 : 1, 1 : 2 and 1 : 1.5, respectively. Crystal structures of Type I compounds -13b-13d In these compounds, there are some differe nces from the apohost structure due to the accommodation of guest molecules. First, the bpeta molecule rotates some degrees from its original position of apohost (45). In 13b two crystalline independent bpeta molecular planes rotate 20 and 40 respectively and in 13c and 13d 40 rotation occurs only. These rotations generate additiona l spaces that the branch groups (-OCH3 and CH3) of aromatic guests are buried inside. (F igure 5.6a) Second, the distance between the chains slightly shrinks from 6.50 to 6.15 . Th ird, the distance of adjacent layers expands from 9.2 to 10.6 . The enhanced distance a llows aromatic solvents to sandwich in between the adjacent layers. The adjacent layers relatively move ca. 3 along the c axis for 13b and a axis for 13c and 13d C-H and interactions were found among the aromatic ring of the host and aromatic guest s. (Figure 5.6b) The solvent molecules repeat each other by a distance of 10.4 . Thus, the solvent molecules were isolated and held tightly inside the channel along the b axis. That makes the solvent difficult to be removed and TGA data showed that their removing temperatures are higher than their boiling points.

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116 ________________________________________________________________________ ________________________________________________________________________ Figure 5.6. Type I host/guest compounds, 13b. (a) Anisole is located inside the channel and methoxyl group is heading to the space created by rotation of bpeta. (b) A view of the packing style. Crystal structures of Type II compounds -13e and 13f Type II host/guest compounds hold twice the amount of solvent molecules as Type I compounds do in the same unit. This make s the structure of Type II different from that of Type I compounds. First, the layers expand completely and repeat each other along the c axis. That expansion gives a maximum se paration with an interlayer distance of ca. 12.4 . Therefore, solvent channels with a size of 8 8 were generated along the (a) (b)

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117 b axis to hold the guests in between. (Fi gure 5.7a) Second, the solv ent molecules have a closer distance (3-4) and generate solvent chains inside the ch annels (Figure 5.7b and 5.7c). In addition, the branch groups (-NO2, and -Cl) of guest molecules are roughly parallel to the channel direction and thus th e rotation angle of bpeta to SBU is only 25 from the ideal position of apohost. Third, these chains pack each other with the distance between the adjacent chains at 6.0 and the chains relatively move each other along the chain direction. Therefore, the distance be tween adjacent SBUs in the channel is expanded from 10.0 (apohost), 10.4 (type I) to 12.2 (type II). Two guest molecules are held together in that space. ________________________________________________________________________ ________________________________________________________________________ Figure 5.7. Type II compound 13e (a) packing view; (b) solvent chain running through the channel; (c) side view of the solvent chain. ( a ) ( b ) ( c )

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118 Crystal structures of Type III compound -13g Compared with Type I and Type II, the compound 13g has a different coordination style. It is cons tructed by an alternative arrang ement of 1 : 1 and 1 : 2 to give the average ratio of 1 : 1.5. (Figure 5.8) Thus the distan ces between adja cent layers have the alternative numbers of 10.4 and 11.4 for 1 : 1 and 1 : 2, respectively. In the same layer, the distance of the adjacent chains is 6.5 , which is same as that of apohost. ________________________________________________________________________ ________________________________________________________________________ Figure 5.8. Type III host/guest co mpound, 13g, benzene molecules are the aromatic solvent sitting between the layers with the alt ernative style of 1:1 and 1:2.

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119 5.2.3. Discussion Self-assembly of copper dicopper tetrabenzoate cluste r with bpeta successfully affords new 1-D coor dination polymers ( 13 ) which are capable of hosting one-ring aromatic solvents. This host framework illustra tes the selectivity and flexibility in hosting one-ring aromatic guests. Three different types of host/guest styles are found which show the molecular recognition ability of the hos t framework. The flexibility of the apohost framework exhibits in three aspects: First, the free rotations of bpeta to SBU create additional space for aromatic branch groups; Second, the chains can slip each other to enlarge the distance between the SBUs and create more room to accommodate guests; Third, the interlayer distance is flexible so th at the layers can expa nd or shrink to fit the guests and hold them in between. A similar structure that is very closely related with 13 was reported recently.248 It is constructed from RhII 2(PhCO2) and pyrazine, in which it sustains the same packing style as that of 13 This reported compound can uptake CO2 23.8 cm3/g at STP conditions, corresponding to an average of 0.81 CO2 molecules per Rh2 unit. 5.3. Compound 14 -[HMTA][Cu2(CH3OC6H4CO2)4] 5.3.1. Experimental Sections In a typical reaction, copper nitrate hemipentahydrate 0.232g (0.999 mmol) and 4anisic acid (0.304 g, 2.00 mmol) in MeOH (15.0 mL) were slowly diffused into an aqueous solution (10.0 mL) of HMTA 0.280g (2.00 mmol). Green crystals were obtained after 3 days in a 53% yield (230 mg). The cr ystals were thermally stable up to 250 C after which the TG curve shows a one step mass loss of about 72% between 250 and 300

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120 C. The most intense peaks observed in th e X-ray powder diffrac tion (XPD) patterns from the bulk sample are consistent with t hose calculated from si ngle-crystal diffraction data. Selected crystallographic parameters are presented in Table 5.3. Complete crystallographic data for compound 14 can be found in Appendix A27. Table 5.3. Selected crysta llographic parameters for 14 Crystal system Space group (#) a () b () c () V (3) Orthorhombic Pbcn (60) 13.3918(11) 15.5991(13) 17.5774(14) 3671.9(5) 5.3.2. Structure Elucidation The structure of [HMTA][Cu2(p-CH3OC6H4CO2)4] 14 possesses 1-D zigzag chains as illustrated in Figure 5.9 and there is no solvent present in the structure. Each HMTA molecule uses two of its four iden tical nitrogen atoms to connect two Copper SBUs and leaves the other two nitrogen at oms open to nothing. The crystal structure of 14 is comprised of HMTA units bridged sequentially by center symmetric SBU to form a zigzag polymeric chain wh ich runs parallel to c -axis. There is one Cu ion, two acid and half HMTA molecules in every asymmetry unit. The distance of Cu-O are 1.910(3) 1.967(3) 1.980(3) 1.997(4) and Cu-Cu in the SBU is 2.6703(12) and the distance of Cu-N between SBU and HMTA is 2.310(4) . Th ese distances suggest that they are all

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121 under normal conditions. The angle of the Cu-C u-N bond is 173, which is very close to 180. This clearly illustrates that Copper square SBUs are perfect linear spacers. ________________________________________________________________________ ________________________________________________________________________ Figure 5.9. (a) View of chain structure an d (b) View of packing style of [HMTA][Cu2(pCH3OC6H4CO2)4] 14. These zigzag chains stack and interdigitate each other along the b and a axis to give a close packing style (Figure 5. 9b). Only weak hydrogen bonding like C-H… and … interactions are found between these chains. (a) (b)

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122 5.3.3. Discussion Supramolecular coordination polymers are in finite structures that are constructed by self-assembly of multi-topi c metal ions/complexes and organic ligands. Among all of coordination polymers, one-dimensional (1 -D) polymers are most common and the simplest.249-251 These 1-D structures are important because they not only provide the basic model for the study of complicated high -dimensional structures, but also serve as building structures for highdimensional structures. A large number of 1-D coordination pol ymers have been reported. Eight topologically different modes of 1-D coordination polymers are summarized in Figure 5.10. 1) linear metal node with linear ligand spacer; 2) angular ligand node with linear metal spacer; 3) angular metal node with linear ligand spacer; 4) angular metal node with angular ligand spacer; 5) trigonal metal node with linear and angular ligand (Note: the ligand can function as linear or angular ligand in same compound due to its flexibility);79 6) “T-shape” metal node w ith linear ligand spacer;131 7) square metal node with angular ligand spacer;252 8) square ligand node with angular metal node253 While cases 1-4 are in chain conformations that can be designed from ditopic metal ions/complexes and ditopic organic linkers, cases 5-8 involve multidentate nodes. Another new feature in cases 58 is that they possess cavities inside the 1-D structures.

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123 Figure 5.10. Eight topologically differen t modes of 1-D coordination polymers In the system of linear SBU and ditopic organic ligand, case 1 and 2 are the only possible topologies. In fact, compound 13 and compound 14 have topologies similar to case 1 and case 2, respectively. A CSD database (CCDC 2004 Conquest Vers ion 1.6) search reveals that among a total number of 507 hits of st ructures that contain copper square SBUs, only 32 are built from the linkage of axial di rections of discrete SBUs .225,233,236,240,244,254-261 All these structures are summarized below according to the dimension, different R groups and ligands (L): Twenty-eight 1-D chain structures with R = CH3: L = HMTA; pyrazine; 2-amiopyrimidine; 1,3-bis(4-pyridyl)propane; nicotin amide; 2,4,6-tris(3’-pyridyl)-1,3,5-triazine; M M M M M M M M MM M M M M M M M M M M M M M M M M M M M M M M M M 1 2 3 4 5 6 7M M M M MM M M M M M M M 8

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124 (1,2-bis(2-pyrazine-3-yl)ethyny l)benzene; 1,8-bis(dimethyl amino)oct-4-en e-2,6-diyne; 2,5-bis(4-pyridyl)-1,3,4-oxadiazole; 2,5-bis(py rid-3-yl)-1,3,4-oxadiazole; 1,1,3,3-tetraisopropyl-1,3-bis(pyridy-3-yl)methoxy; 1,8-bis(3,5-dimethyl -1-pyrazolyl)-3,6dithiaocatane; 1,4-diazabicyclo(2,2,2)octane. R = tBu: L = pyrazine; dioxane; 3pyridynitronyl nitroxide; be nzo-2,1,3-thiadiazole. R = Ph : L = 2,4,6-tris(3’-pyridyl)1,3,5-triazine; pyrazin e; dioxane. R = C6F5: L = dioxane. R = 3,3’di methyl-butane: L = dioxane. R = 2-acetylphenoxylacetate: L = 2-am io-pyrimidine. R = Et: L = dioxane. R = C(Cl)3C: L = caffeine. R = H: L = dioxane. R = 2-Cl-pheonxyethanoate: L = 2-amiopyrimidine. R = 3-methoxylpheyl ac etate: L = 2-amio-pyrimidine. One 1-D double strand structure262 with R = CH3: L = 5,10,15,20-tetrakis(2-(4pyridy-carboxylamino) phenyl-porphyrin. Two 2-D (4,4) layer structures236,262 with R = CH3: L = 5,10,15,20-tetrakis(2-(4pyridy-carboxylamino)phenyl-porphyrin; 1,2,3,4 -tetrakis(4-pyridyl)cyclobutane. One 2-D (6,3) layer structure261 with R = CH3: L = 1,3,5-tris (4-pyridyl)-2,4,6triazine. All these compounds clearly demonstrat e that R groups are dominated by CH3 (17/32). Most ligands contain aromatic c oordination N atoms ( 18/32) and only three ligands contain aliphatic coordi nation N atoms. There are also some structures containing oxygen-based ligands such as dioxane (4/32) or ligands mixed with oxygen and nitrogen (3/32). Only one structure (CSD# BABDEN) was reported from self-assembly of HMTA and SBU.263 This structure involves ditopic HMTA coordinating with linear copper acetate SBU that has the exact same c oordination style as that in compound 14

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125 Although there are possibili ties of building 0-D polygons such as “square box” and helix structures based upon angular ditopi c ligands and linear SBUs as illustrated in Figure 5.11, straight (11/28) and zigzag (17/28) chains are the only observed structures until now. Figure 5.11. Two other possible topologies from angular node and linear spacer: square box (a) and 1-D helix (b) In conclusion, the chain structures th at we have made are common structures similar to those reported. They added to the ever-increasing fa mily of coordination polymers that are constructed from linear copper SBUs and multidentate ligands. 5.4. Compound 15 -[HMTA]2[Cu2(p-NO2PhCO2)4]3 5.4.1. Experimental Section In a typical reaction, copper nitrate hemipentahydrate 0.232g (0.999 mmol) and 4nitrobenzoate acid (0.334 g, 2.00 mmol) in MeOH (15 mL) were slowly diffused into an aqueous solution (10.0 mL) of HMTA 0.280g (2.00 mmol). Green crystals were obtained after 3 days. Yield, 225 mg, 51% based on Cu. Th e crystals were thermally stable up to 300 C after which the TG curve shows a one step mass loss of about 78% between 300

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126 and 450 C. The most intense peaks observed in the X-ray powder diffraction (XPD) patterns from the bulk sample are consistent with those calculated from single-crystal diffraction data. Selected crystallographic parameters are presented in Table 5.4. Complete crystallographic data for compound 15 can be found in Appendix A28. Table 5.4. Selected crysta llographic parameters for 15 Crystal system Space group (#) a () = b () c () V (3) Trigonal P-3 (147) 15.756(5) 12.894(6) 2772.0(18) 5.4.2. Structure Elucidation Compound 15 consists of a honeycomb sheet stru cture as illustrated in Figure 5.12. Every six-member ring is defined by six trigonal nods of HMTA in the corners and six linear Cu2(p-NO2PhCO2)4 spacer in the sides. Equatori al nirtophneyl groups fill the large honeycomb cavities. There is one Cu i on, two acid and one third HMTA molecules in every asymmetry unit. The distance of Cu-O are 1.919(10), 1.942(9), 1.949(7) and 1.964(7) , Cu-Cu in the SBU is 2.610(3) and Cu-N between SBU and HMTA is 2.179(9) . This honeycomb has the diagonals of ca. 19 and sides of ca. 10 . All honeycombs take a chair (Figure 5.12b) style connection to give a puckered layer due to the psudotrigonal HMTA nods. These layers stac k each other in AAA mode along the c direction with an interlayer distance ca. 12.0 .

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127 ________________________________________________________________________ ________________________________________________________________________ Figure 5.12. Overhead and perspective views of the Honeycomb network (Nitrophneyl groups and H atoms omitted for clarity) seen in the crystal structure of [HMTA]2[Cu2(p NO2C6H4CO2)4]3, 15. 5.4.3. Discussion Structures with honeycomb topology are very attractive due to their natural beauty. In the context of cr ystal engineering, building a honeycomb network with large building blocks will create hexagonal channe ls inside the network. There are several classical examples of building honeycomb ne tworks using H-bond, such as layer network of trimesic acid (btc)264 and its derivates,265-269 1:1 mixed cyanuric acid and melamine,270272 and 1:1 mixed guanidinium and organomonosulfonate.273,274 In the context of coordination polymer, three major de sign strategies have been used : trigonal metal node with linear ligand spacer; 151,275

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128 trigonal organic ligand node with linear metal spacer; 141,276,277 trigonal organic ligand node with trigonal metal node. 166,278,279 Compound 15 is constructed by applying the second strategy. In this compound, HMTA functions as a trigonal ligand for it only uses three of its four nitrogen atoms to create coordination bonds. Figure 5.13 illust rates how HMTA can be viewed as a pseudo trigonal node when projected along the 3-fold axis. Due to the irregular shape of the trigonal node, all network hexagons take a ch air conformation to give an undulated layer structure. Nitro-phenyl groups fill the hexa gonal cavities with sides of 1.00 nm and diagonals of 1.90 nm and no solvent molecules are found. Figure 5.13. a pseudo trigonal node generated by HMTA Only one related (6,3) networ k was reported by Robson et.al.261 As illustrated in Figure 5.14, the network is built from copper acetate SBUs and large organic trigonal ligand, 1,3,5-tris (4-pyridyl)-2,4,6 -triazine (tpt). It possesse s hexagonal channels with a dimension of ca. 31 . Unfortunately, the created large cavities are diminished by the staggered packing of adjacent layers. In summary, honeycomb structures can be designed and predicted based upon the pseudo trigonal node of HMTA and linear SB U spacers. Large hexagonal channels can be created inside this networ k. Unfortunately, in this case, these channels are filled by

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129 carboxylate groups. As it is di fficult to retain the same topology by reducing size of carboxylate groups, a better strategy to create porous honeycomb networks is to use other tridentate ligands that have strong interaction with SBUs. ______________________________________________________________________________________ ______________________________________________________________________________________ Figure 5.14. Honeycomb structure from copper acetate and tpt 5.5. Compound 16 -[HMTA]3[Cu2(C2H5CO2)4]5, the first two-dimensional supramolecular (5, 3 4)-net238 5.5.1. Experimental Section In a typical reaction, copper nitrat e hemipentahydrate 0.232g (0.999 mmol) and propionic acid (0.144 g, 2.00 mmol) in MeOH ( 15 mL) were slowly diffused into an aqueous solution (10.0 mL) of HMTA ( 0.280 g, 2.00 mmol). Green crystals were obtained in days. Yield, 137 m g, 55% based on Cu. The crysta ls are thermally stable up to 200 C after which the TG curve shows a one step mass loss of about 70% between 200 and 300 C. The most intense peaks obser ved in the X-ray powder diffraction (XPD)

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130 patterns from the bulk sample are consistent with those calculated from single-crystal diffraction data. Selected crystallographic parameters are presented in Table 5.5. Complete crystallographic data for compound 16 can be found in Appendix A29. Table 5.5. Selected crysta llographic parameters for 16 Crystal system Space group (#) a () = b () c () V (3) Tetragonal P-42(1)m (113) 22.9167(15) 10.7915(10) 5667.4(7) 5.5.2. Structure Elucidation The structure of [HMTA]3[Cu2(C2H5CO2)4]5, 16 consists of the first example of periodic titling of pentagon based 2-D sheet [(5 )-net] as illustrate d in Figure 5.15. Every five-member ring is defined by five HMTA mo lecules and five SBU spacers. In this compound, HMTA nodes take an undistorted tetrah edral geometry and coordinate to either three or four copper SBU spacers in a 2:1 ratio. The overhead view (Figure 5.15a) is a projection down [001] and illustrates how the network projects onto the plane to give the (5,3 4)-net. The sheets of 16 are curved and the packing of adjacent sheets appears to be the consequence of shape considerations (Figure 5.15b). In this compound, there are ten dicoppe rtetracarboxylate SBUs and six HMTA molecules in each unit cell with a Z value at 8. The dicopper tetracarboxylate spacers are within normal conditions: Cu-O distances ar e between 1.886(8) and 1.967(5) , axial Cu-

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131 N distances are 2.190(10), 2.198(6) and 2.225(6) and Cu-Cu separations of 2.576(3) and 2.5873(14) . Ethyl groups efficiently fill the pentagonal cavities with sides of 1.00 nm and diagonals of 1.54 nm and no solvent molecules are found. Th e sheets are curved, and stack each other with AAA mode w ith interlayer distance at 1.08 nm. ________________________________________________________________________ (a) (b) ________________________________________________________________________ Figure 5.15. Overhead and pers pective views of the (5,3 4)-network The ethyl groups (omitted for clarity) fill the pentagonal cavities, which have sides of 1.00 nm and diagonals of 1.54 nm.

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132 Another striking feature of th is net is that it is in nocentrosymmetric space group P-421m. Crystal structure illustrates that only one layer is selected in each cell along the c direction and an HMTA molecule is sitting in the center of the cell that prevents any center symmetry. Remarkably, adj acent layers stacked along the c axis exactly repeat each other and prevent any inve rsion center in between the la yers. That may attribute to the consequence of shape considerations to get the most efficient packing. This periodical pentagon pa ttern is known as Cairo ti ling or MacMahon’s net. The tiling is also common for pa ved sidewalks in Egypt. It has been featured by P.A. MacMahon,280 Michael O’Keeffe and Bruce G Hyde.281 5.5.3 Discussion The crystal structure of 16 reveals that 3 equivalents of hexamethylenetetramine, HMTA, can be complexed with 5 equivalents of Cu2(C2H5CO2)4 to afford [(HMTA)3(Cu2(C2H5CO2)4)5]n, the first example of a modular (5,3 4)-network. Although it is true that regular pentagons cannot tile the pl ane, there are in fact 14 different types of convex pe ntagons that tile the plan e (see Appendix B). From a topological perspective, some of these 14 tilings282-284 are mathematic pentagon. However, they are not “chemistry” pentagons simply because each pentagon contains six or seven nodes. For example, Type 1 tiling is actually a network with (6, 3) topology. If we rule out all these kinds of tilings, the re maining tiling are Type 4, 5, 6, 7, 8 and 9 in two groups based upon the connectivity of the vertices: five (5,3 4)-nets (type 4, 6, 7, 8, 9) and one (5,3 6)-net (type 5). Among all these five (5,3 4)-nets, Type 4 and 8 have similar arrangements of pentagons with nodes sequence of (4,3,4,3,3); Type 6 has another

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133 (a) (b) (c) sequence of (4,4,3,3,3); and Type 7 and 9 ha ve both arrangements of (4,3,4,3,3) and (4,4,3,3,3). Figure 5.16 illustrates three net. Net (a) is similar to Type 4 and 8; net (b) is similar to Type 6 and net (c) similar to Type 5. These three nets are relatively simple and in principle chemically accessible. Compound 16 has a topology similar to the (5,3 4)-network illustrated in Figure 5.16a. In its most symmetric form, this netw ork has 4 equidistant li nks per pentagon, and trigonal and square planar node s in the ratio of 2:1 with the arrangement of (4,3,3,4,3). Figure 5.16. There nets of 14 tilings that contain congruent pentagons. When one thinks about a regular pentagon ha ving five angles (108) that are very close to the angles of a tetrahedron (109.5 ), it would not be surprising that HMTA molecules could act as nodes to generate pentagons. Figure 5.17 illustrates how a tetrahedral node can be viewed as either a trigonal or a square planar node when projected down the 3-fold or 2-fold axis, re spectively. The exploita tion of a tetrahedral node to generate this network imposes certa in conditions: the network cannot be planar; the tetrahedral node must be able to adopt both a 3-fold and 4-fold coordination sphere; the individual pentagons must be non-planar, that is they ar e cyclopentanoid. In this case, HMTA is a suitable tetrahedral node, as it is known to adopt one-, two-, threeand fourfold coordination.

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134 Figure 5.17. A tetrahedral node projected down the 3-fold axis (a), and 2-fold axis (b) affording pseudo trigonal and pseudo sq uare geometries, respectively. Finally, the generation of nanoscale cycl opentanoid rings from tetrahedral nodes is potentially relevant since when such rings ar e fused they necessarily exhibit curvature. They therefore represent a possible entry into neutral spheroid struct ures that would be related to the discrete molecular dodecah edra recently reported by Stang et al.285,286 Alternatively, with a change in stoichiometry, infinite frameworks based upon fused distorted dodecahedra (pyritohedra) might be formed, as well as other 2-D network structures such as the (5,3 4)-net illustrated in Figure 5.16b. 5.6. Compound 17 -[HMTA][Cu2(PhCO2)4]2 5.6.1. Experimental Section In a typical reaction, copper nitrat e hemipentahydrate (0.233 g, 1.00 mmol) and benzoate acid (0.244 g, 2.00 mmol) in MeOH ( 15.0 mL) were slowly diffused into an aqueous solution (10.0 mL) of HMTA ( 0.280 g, 2.00 mmol). Green crystals were obtained after 2 weeks. Yield, 221 mg, 65% based on Cu. The crystals are thermally stable up to 250 C, after which the TG cu rve shows a mass loss of about 70% between 250 and 350 C. The most intense peaks obser ved in the X-ray powder diffraction (XPD) (a) (b)

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135 patterns from the bulk sample are consistent with those calculated from single-crystal diffraction data. Selected crystallographic parameters are presented in Table 5.6. Complete crystallographic data for compound 17 can be found in Appendix A30. Table 5.6. Selected crysta llographic parameters for 17 Crystal system Space group (#) a () = b () c () V (3) Tetragonal I4(1)/a (88) 15.9763(16) 23.558(3) 6013.1(12) 5.6.2. Structure Elucidation The structure of [HMTA][Cu2(PhCO2)4]2, 17 is revealed by Fi gure 5.18. It exists as a one-fold modular diamondoid network. Th e tetrahedral HMTA nodes are propagated by Cu2(PhCO2)4 spacers that are complexed at their ax ial sites by HMTA n itrogen atoms. There is one Cu atom, two benzoates a nd one forth HMTA molecules in every asymmetry unit. The distance of Cu-O are 1.962(3), 1.958(3), 1.961( 4) and 1.968(3) , Cu-Cu in the SBU is 2.5646(11) and Cu-N between SBU and HMTA is 2.189(4) . The HMTA molecules are separated by SBUs w ith a distance of 9.925 and there is very little distortion in the structure compared to that of an idealized cubic diamondoid structure. Two angles are found between ev ery two sides of a tetragonal node: 107.2 and 110.2. The large cavities in 17 are filled by the equatori al phenyl groups of each Cu2(PhCO2)4 propagator and there is no solven t present in the structure.

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136 ________________________________________________________________________ ________________________________________________________________________ Figure 5.18. Diamondoid networks using linear SBU’s and HMTA tetrahedral nodes. (Phenyl groups were omitted for clarity)

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137 5.6.3. Discussion It has been a long time since people st arted to think about building diamondoid networks62 with molecular components arranged by intermolecular intera ctions such as H-bond,287,288 X bond289,290 and coordination bond.164,291-297 The common design strategy used here is to find molecules or molecular structure moieties that possess Td symmetry. Therefore, it is not surprising that the potential candidates are pre-selected from tetrafuncti onal adamantanes, tetrafunctional methanes and tetrafunctional cube like structures. In the context of coordi nation polymers, three major design strategies have been used: me tal ion acts as tetrahedral node and organic linear ligand as spacer, or ganic ligand act as tetrahedral node and linear metal ion/complex as spacer or both organic lig and and metal ion are tetrahedral nodes. Compound 17 is designed using the second strategy. HMTA and SBUs are preselected for their symmetry. This was actua lly the first compound when we started to study the possibility of connec ting linear SBUs into coordi nation polymers. The topology is exactly the same as what we had origina lly designed. However, fu rther studies reveal that reducing or increasing the size of R groups will lead to the destruction of diamondoid topology, which prevent us from obtaining po rous materials based on this framework. After compound 17 was synthesized, a closely related structure245 that exhibits the same topology was found in CSD database. [Mo2(MeCO2)40.5HMTA 0.5CH2Cl2] exists as diamondoid network as illustrated in Figur e 5.19. This compound has several different features from compound 17 : Acetate Mo SBU is used; It has guest molecules;

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138 The HMTA molecule is not purposel y added but created by a reaction It is a doubly interpenetrated structure. ________________________________________________________________________ ________________________________________________________________________ Figure 5.19. A perspective view of [Mo2(MeCO2)40.5HMTA 0.5CH2Cl2], a double interpenetrated diamondoid network Interpenetration is a common phenomenon in diamondoid structures. Literature survey298 shows that the interpen etration number can be any number between 2 and 11. The absence of interpenetration in 17 is a consequence of the steric bulk of the phenyl groups. In fact, calculation shows that th e structure has no void space for guest and phenyl groups occupying 68.5% space of the crystal structure. Reduction of phenyl group into methyl group creates more than 50% void space that is sufficient enough to accommodate another diamondiod network as found in this reported structure. Interestingly, the self-assembly of copper acetate SBU and HMTA results in a chain

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139 structure rather than a diamondoid structure. It clearly demonstr ates that the interaction of Cu-N is weaker than th e interaction of Mo-N. In summary, a close packing diamondoi d structure was obtained from copper benzoate SBU and HMTA. The phenyl groups fill the void space that is created by HMTA and SBU skeleton to prevent guest molecules and interpenetration. Further studies of porous diamondoid network coul d focus on the HMTA and other transition metals based SBUs such as Mo, Ru, Rh, in which strong interaction between M-N is expected. 5.7. Compound 18 – (10,3)-a networks, [Melamine]2[Cu2(C2H5CO2)4]3 and [HMTA]2[Cu2((CH3)3CCO2)4]3 ( 18a and 18b ) 5.7.1. Experimental section Synthesis of compound 18a : To a 10.0 mL methanol solution containing copper nitrate hemipentahydrate (0.047 g, 0.20 mm ol) and sodium propionate (0.040 g, 0.40 mmol) was added melamine (0.025 g, 0.20 mmol). Green crystals were collected after the solution was left to stand under ambient conditions for one week. Yield (0.020g, 40% based on copper). Synthesis of compound 18b : A 15.0 mL methanol so lution containing copper nitrate hemipentahydrate (0.233 g, 1.00 mmol ) and t-butyl carboxylic acid (0.204 g, 2.00 mmol) was slowly diffused into a soluti on of HMTA (0.071 g, 0.50 mmol) in 10.0 mL water. Large block green crystals were obtai ned after the reaction was left to stand at ambient conditions for one week. Yield (0.230g, 74% based on copper).

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140 18a, 18b are air stable. The thermal stabilities of compounds 18a and 18b were studied by TGA. Compound 18a is stable to ca. 200 C, at which point it undergoes sharp weight loss (53%). Compound 18b is stable to ca. 250 C, at which point it undergoes a ca. 68% weight loss. The most intense p eaks observed in the X -ray powder diffraction (XPD) patterns from the bulk sample are cons istent with those cal culated from singlecrystal diffraction data. Table 5.7: Selected crystallo graphic parameters for 18a and 18b Crystal system Space group (#) a () b () c () beta () V (3) 18a Tetragonal P4(2)/nbc (133) 20.531(2) 20.531(2) 13.554(3) 90 5713.3(14) 18b Monoclinic C2/c (15) 36.648(3) 28.129(2) 26.131(2) 133.6580(10) 19489(2) 5.7.2. Structure Elucidation Compound 18a crystallizes in space group P4(2 )/nbc. As illustrated in Figure 5.20, dicoppertetrapropionate SBUs are conne cted in axial directions by melamine molecules through N(aromatic)-Cu bonds. Sin ce all three aromatic N atoms in each melamine are connected, the resulting structure mu st be an infinite network, in this case a (10,3)-a network.

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141 ________________________________________________________________________ ________________________________________________________________________ Figure 5.20. Environment of a melamine molecule coordinated to three copper SBU (R groups in SBU were omitted for clarity) affording trigonal node. The Cu-O distances [1.908(6)-2.011(7) ] within the SBU’s fall in the expected range,299,300 however, the Cu-Cu distances [2.714(2 )-2.7504(18) ] are significantly larger than that of the isolat ed propionate SBU (Cu-Cu 2.599-2.611 ).301 The electronic nature of the axial ligands could explain th is observation and similar trends have been found in related compounds.302 The Cu-N distances are 2.274(6), 2.274(6) and 2.303(8) whereas the Cu-Cu-N angles are 177.63(15), 177.63(15), and 180 Careful examination of the crystal structure of compound 18a reveals that it consists of four independent (10, 3)-a netw orks (See Figure 5.21a), two left hand and two right hand nets, that interpenetrate. The overa ll structure is theref ore racemic and gives what is to our knowledge, the first exampl e of a 4-fold racemi c (10,3)-a coordination compound. A single (10,3)-a network, which is left handed, is illustrated in Figures 5.21b and 5.21c. A view of the 41 helix portion of the networ k is presented in Figure 5.21d.

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142 ________________________________________________________________________ ________________________________________________________________________ Figure 5.21. (a). A view down the c axis illust rateing the four interpenetrating networks of [Melamine]2[Cu2(C2H5CO2)4]3 18a; (b). A single net of (10,3)-a network which is left handed along the c axis; (c). A view along the 3-fold axis of the same single net; (d). A view of the 41 helix from part of one independent net (carboxylate groups were omitted for clarity in a-c). (a) (b) (c) (d)

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143 There is deviation from ideal symmetry since, although the melamine molecules serve as 3-connected nodes, they sit around crystallographic 2-fold symmetry. Furthermore, two Cu –N bonds deviate from th e plane of the triazi ne ring with torsion angles of ca. 14 (Nitrogen atoms were used for the torsion angle calculation) Therefore, the (10,3)-a topology of compound 18a deviates from ideal (10,3)-a symmetry and crystallizes in tetragonal ra ther than cubic symmetry. Examination of the structure of 18b reveals the formation of another (10,3-a) network in which HMTA connects three SBU’ s. Figure 5.22 presents an illustration of this structure. HMTA is simplified as a point node and the SBU’s are represented as linear spacers. Although the 3D network formed by compound 18b can be classified as (10,3)-a from topological perspective, it possesses lower symmetry than 18a because of the pseudo trigonal geometry of the HMTA moieties and 18b crystallizes in monoclinic space group C2/c. As expected, the SBUs ar e connected in axial directions by HMTA molecules. The Cu-O distances [1.909(7)1.996(7) ] and Cu-Cu di stances within the SBU are 2.611(2) and 2.617(2) and the Cu -N bonds range from 2.219(8) to 2.251(7) . A single network of 18b is presented when viewed down the 4-fold and 3-fold axis in Figures 5.23a and 5.23b, respectively. Two types of channels can be seen within the network. However, these channels are filled by the racemic interpenetration of a second (10,3)-a net (Figure 5.23c).

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144 ________________________________________________________________________ ________________________________________________________________________ Figure 5.22. (a). One (10,3) circl e consists of 10 HMTA molecule s as nodes and 10 copper square SBUs function as linear spacers; (b). A single left-hand net of the (10,3)-a network in 18b (Carboxylate groups were omitted for clarit y and HMTA was replaced by tetradedral node) ________________________________________________________________________ ________________________________________________________________________ Figure 5.23. The (10,3)-a network of [HMTA]2[Cu2((CH3)3CCO2)4]3 18b. (a). View along the pseudo41 axis of one single net; (b). View along the pseudo -3-fold axis of one single net; (c). Racemic interpenetration of two (10,3)-a nets. (Carboxylate groups were omitted for clarity) (a) (b) (a) (b) (c)

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145 5.7.3. Discussion Over 25 years ago, A.F. Wells200 presented a comprehensive summary of (10,3) networks. The (10,3)-a network deserves special attention sinc e a single network possesses supramolecular chirality. As chiral compounds ha ve potential applications in enantioselective separations and asymmetric catalysis,178,303,304 it should therefore not be surprising that they have subsequently b ecome synthetic targets for supramolecular chemists. In 1993, Decurtins305 and coworkers reported a 1-fold (10,3)-a network sustained by an anion framework, [FeII 2(ox)3]n 2n-. Subsequently, Ciani243,306 and Robson307 reported cationic (10,3)-a networks vi a metal ion/organic amine coordination and in 1998, Rosseinsky308 reported the first example of neutral (10,3)-a network in a metal/carboxylic acid system. ________________________________________________________________________ ________________________________________________________________________ Figure 5.24. (10,3)-a network (right hand) projection along 4-fold axis and 3-fold axis From a design perspective, there are thr ee different approaches that might be readily exploited to c onstruct (10,3)-a topology:309-315 (a) ten metal ions define the 3-

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146 connected nodes and ten linear organic mol ecules connect these nodes into a 10-gon, (b) ten tridentate organic ligands define the 3-c onnected node and ten metal moieties serve as linear spacers to connect ligands into a 10-gon, and (c) five trid entate metal ions and five tridentate organic molecules self-assemble into a 10-gon. The nature of the (10,3)-a network means that it inherently possesses large void spaces that are appropriate for occupation by counter ions, guest molecules or selfinterpenetration.316 When equal numbers of left (L) and right hand (D) (10,3)-a networks interpenetrate then the homochirality of the individual networks will cancel and the resulting compound will be racemic. This has indeed been the case for most of the (10,3)a networks that have thus far been characterized.306,307,309,311,313 Indeed, any tridentate amine that appr oximates trigonal symmetry and any linear dimetaltetracarboxylate moiety can in pr inciple afford (n,3) topology networks. [Melamine]2[Cu2(C2H5CO2)4]3 and [HMTA]2[Cu2((CH3)3CCO2)4]3 ( 18a and 18b ) are thus synthesized with (10,3)-a networks. Unfo rtunately, they are a ll racemic structures due to the interpenetration of racemic pa ir of networks. Nevertheless, these two compounds would appear to be prototypal fo r a wider range of compounds with (n,3) topology since either modifying the R gr oup of the carboxylic acid or using other tridentate organic ligands represent simp le ways to expand the chemistry without modifying the symmetry of the molecular bu ilding blocks. Furthermore, the use of different transition metals or the presence of guest or template molecules would also provide opportunities to expand the range of compounds that might be accessible. The preparation of a neutral 1-fold (10,3)-a structure would represent a particularly attractive synthetic target because it would be homochiral and it is inherently

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147 an open framework structure. In this contex t, the design of ionic (10,3)-a netwrok is one of the possible routines since counter ions ha ve to occupy part of the void space. The use of bulky substituents on the SBUs might also be used to prevent self-interpenetration. However, all these methods would mitigate the le vel of porosity in the resulting structure. 5.8 Conclusions In this Chapter, all compounds are constr ucted from linear copper SBUs in which equatorial directions are term inated by monocarboxylates (RCO2). Two effects were studied in modification of R groups in this work: size effect and aromatic effect. Three multitopic amines were used as illustrated in Figure 5.2 with a range of coordination numbers from 2 to 4. A striking feature of this system is th at, unlike the interaction of Cu-O at equatorial direction, the interaction of Cu-N at axial direction is weak. It can be explained by the well-known John-Teller effect of the Cu (II) ion. This special phenomenon causes the unequal distribution of elect ronic density around the Cu i on and axial direction has a longer bond distance compared to th e equatorial directions (see next section of statistical data from CSD). Another reason is, the nitroge n atoms in HMTA are aliphatic and have a weaker interaction than aromatic nitrogen atoms. This weak interaction causes less chance for the creation of porous material and results in the flexibility of coordination numbers. There are two crucial design elements: the nature of the acid functionality, R, in the Cu2(RCO2)4 linker, and the ratio, X between HMTA and linker. Networks can be obtained by varying these condi tions: 1-D zigzag structures are observed when HMTA

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148 coordinates to two Cu2(RCO2)4 linkers (R = H, Me, pCH3OC6H4 or t-Bu, X = 1:1), both 2-D three-connected topologies (6,3) 15 (R = p -NO2C6H4) and also 3-D topologies (10,3)-a 18b (R = t-Bu) result When HMTA coordinates to three linkers ( X = 2:3), a diamondoid structure 17 results from the coordination of four linkers to HMTA (R = C6H5, X = 1:2). For the conditions R = ethyl and X = 3:5, 16 is obtained. Other nets are also expected to result by varying R groups and X The design strategy of this modular chemis try can be divided into three aspects: variation of metal ions, modification of R groups and the selection of appropriate multidentate amines. In particular, there are numerous transition metals, numerous carboxylates and numerous amines that are availa ble to incorporate in to such structures. These compounds might therefore represent suit able prototypes for structure/function studies, especially in the area of molecular magnetism, since Cu2(RCO2)4 based structures have been shown to be magnetically active. In conclusion, we have demonstrated th e feasibility to syst ematically modulate mono carboxylate groups in order to manipulate the structures of resulted coordination polymers. As a result, six structures with si x different topologies were obtained. Future research interest might be focused on the a pplication of these coordination polymers as well as modification of R groups loaded with useful information. The modification of R groups could transfer useful properties su ch as function groups or chirality from molecular into the resulted crystalline materi als. This research may set up a prototype method for searching for functional mate rials with fine-tuned properties.

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149 5.9. CSD database studies of Di metal tetracarboxylate SBUs There are many interaction patterns between metal i ons and carboxylic acid. Dimetal tetracarboxylate (SBU) is well-docum ented and broadly existed in coordination chemistry. It is constructed from two metal ions, four carboxylates and two axial ligands, in which the two metal ions ar e in the center, attached by f our carboxylates in such a way that D4h symmetry is created. The eight MO coordination bonds in each SBU largely increase the stability of this basic unit. Thus, it is not surp rising that this building unit could serve as supramolecular synt hon to construct porous materials.317 A summary of the number of reported SBU structures for the transition elements from CSD database (CCDC 2004 Conquest Versi on 1.6) search is shown in Table 5.8. It shows that about two-thirds of transition meta l ions have this stru cture pattern. Among all of these ions, Cu, Rh, Ru, Mo, Cr take about 90% of the total number of 1164 hits and Cu is the dominant metal ion that takes 43.6% of total hits. Table 5.8. Number of reported SBU structures for the transition elements Sc Ti V Cr MnFe CoNi Cu Zn 0 3 6 48 2 17 8 15 507 11 0.0% 0.3% 0.5% 4.1% 0.2% 1.5% 0.7% 1.3% 43.6% 0.9% Y Zr Nb MoTc Ru Rh Pd Ag Cd 8 0 0 106 6 114 249 0 0 4 0.7% 0.0% 0.0% 9.1% 0.5% 9.8% 21.4% 0.0% 0.0% 0.3% La Hf Ta W R R e e Os Ir Pt Au Hg 22 0 0 17 9 5 0 3 0 2 2.4% 0.0% 0.0% 1.9% 1.0% 0.6% 0.0% 0.3% 0.0% 0.2%

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150 The first crystal structur e of copper SBU [CSD #CUAQAC, Cu2(CH3CO2)42H2O] was reported in 1953.318 The initial research interests focus on the magnetic properties and Cu-Cu interactions of discrete SBU structures. However, in the past decade, research interests were sh ifted into constructing SBU based porous coordination polymers. A statistical study was conduc ted and is summarized in Table 5.9 and 5.10 with average, minimum and maximum bond values for copper SBU compounds with nitrogen donor ligands at axial directions (188) and oxygen donor ligands at ax ial directions (229), where atomic coordination information is av ailable in the CSD database. Median and standard deviation values are also listed. As illustrated in Table 5.9, the Cu-O distances range between 1.844 and 2.060 with an av erage of 1.973 (standard deviation = 0.040). The distances between Cu-N (axial direction) vary between 2.005 and 2.360 (average 2.175 , = 0.052). The distances between Cu-Cu vary between 2.585 and 3.261 (average 2.695 , = 0.122). The results in Table 5.10 show that there are no significant differences between the N-donor ligand and O-donor ligands at axial directions. Table 5.9. Copper SBU with nitrogen dono r ligands at axial directions (188 hits) Cu-O Cu-N Cu-Cu Min 1.844 2.005 2.585 Max 2.060 2.360 3.261 Average 1.973 2.175 2.695 Median 1.967 2.170 2.659 STDVA 0.040 0.052 0.122 The distributions of Cu-O, Cu-N and Cu-Cu distances are shown in Figure 5.25, Figure 5.26 and Figure 5.27, respec tively. Distributions of Cu -O and Cu-N distances are

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151 significantly narrower th an that of Cu-Cu distances. Th is phenomenon suggests that there is no strong interaction (or bond interaction) between two copper ions. The most probable Cu-O distance is 1.97 and the most probable Cu-N distance is 2.18 . Cu-O bond distance distribution0 10 20 30 40 50 60 701.89 1. 9 1.91 1.92 1 93 1.94 1.95 1. 9 6 1.97 1.98 1. 9 9 2 2.01 2 02 2.03Bond distanceHits Figure 5.25. Histogram showing the distribution of Cu-O dist ances among the structures containing the SBU in coordination with two N-donor and four carboxylates Cu-N bond distances distribution0 5 10 15 20 25 30 352. 01 2. 03 2. 05 2. 07 2. 09 2.11 2. 13 2.15 2.1 7 2 .19 2.21 2. 23 2.25 2. 27bond distancehits Figure 5.26. Histogram showing the distribution of Cu-N dist ances among the structures containing the SBU in coordination with two N-donor and four carboxylates

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152 Cu-Cu distance distribution0 2 4 6 8 10 12 14 16 18 202 .55 2.5 7 2.59 2. 61 2.63 2 .65 2.6 7 2.69 2. 71 2.73 2 .75 2. 77 2.79distancehits Figure 5.27. Histogram showing the distribution of Cu-Cu distances among the structures containing the SBU in coordination with two N-donor and four carboxylates Table 5.10. Copper SBU with oxygen donor ligands at axial directions (229 hits) Cu-O (eqatorial dirction) Cu-O (axial direction) Cu-Cu Min 1.830 1.913 2.553 Max 2.041 2.332 3.256 Average 1.968 2.154 2.636 Median 1.967 2.153 2.623 STDVA 0.036 0.053 0.083 The statistic results of 20 compounds from this work are summarized in table 5.11. The results show that the Cu-O dist ances range between 1.886 and 2.011 with an average of 1.963 ( = 0.024), Cu-N distance range between 2.145 and 2.310 (average 2.195 , = 0.043), the Cu-Cu distance s are between 2.576 and 2.750 (average 2.649 , = 0.043). Apparently, the structure pa rameters from our crystal data are under normal conditions.

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153Table 5.11. Copper SBU with nitrogen atoms at axial directions (this work) Cu-O Cu-N Cu-Cu Min 1.886 2.145 2.576 Max 2.011 2.310 2.750 Average 1.963 2.195 2.649 Median 1.965 2.179 2.664 STDVA 0.024 0.043 0.043

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154 C C h h a a p p t t e e r r 6 6 C C o o n n c c l l u u s s i i o o n n s s & & F F u u t t u u r r e e D D i i r r e e c c t t i i o o n n s s 6.1. Summary This dissertation focuses on crystal engineering of coor dination polymers that are based on the well-defined metal-organic s upramolecular synthons. The introduction part presents the concept of crystal engineer ing and its core valu e – placing atoms or molecules at the right positions in solid state. The arrangement of atoms or molecules requires the knowledge of intermolecular inte ractions and recognition phenomena in the solid state. Therefore, supramolecular synthons lie in the core position of design of novel functional materials. Although this concept or iginally focused on the crystal engineering of molecular solids, it applies equally well to the crystal engin eering of coordination polymers. Metal-organic supramolecular synthons are these metal-organic interaction patterns that are stable and broadly existed in coordinati on chemistry. They contain the information needed for the pre-selection of me tal ions and organic multidentate ligands to build supramolecular structures in a more precise and pr edictable way. Although this dissertation only provides two exam ples of such synthons: Zn(RCO2)(py)2 and

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155 (L)2M2(RCO2)4, metal-organic supramolecular synthons could be all of reliable metalorganic interaction patterns from coordination chemistry. 6.2. Crystal Engineering vs Design Here arises a fundamental question: Can we really design a crystal? The research results in this dissertation clearly show the difficulties. First, there are many possible interaction pa tterns for any set of the preselected starting materials. For example, Compounds 2, 5, and 6 are all built from zinc /pyridine/btc. Compound 2 is built from mononuclear chromophore and compound 5 and 6 are built from dimetal SBUs. Second, organic molecules are flexible and have the freedom to change their conformations. This is clearly demonstrated by bdc molecule in compound 12 Third, there are also many possible topologies even though metal organic in teractions can be fixed in one mode. For example, four different structures ( 7, 8, 9, 11 ) are obtained from copper/bdc system and they are all cons tructed from planar square SBUs. The reality is that crystal engineering is pervaded by supramolecular isomers. For example, there are four different ways for f our bdc molecules to bind around the dicopper center in a single square SBU. At least three different types of comb inations (3, 4 and 6) of SBUs are found in this work. There are four different situations for the combination of tetrakis -SBUs linked by bdc molecules into a square shape. All of these tell us that, based on principle, there are a large number of possibl e situations. From this point of view, it seems as if design doe s not exist at all. However, we have an intention to design coordination polymers by judicious selection of metal-organic synthons and organi c ligands. Many successful examples have

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156 been achieved by applying this strategy. In this dissertation, compounds 7, 13 and 17 are pre-designed structures. Compounds 5, 12 and 16 are the less predictable and designable structures. All the other compounds are predicta ble structures. Most of times, the failure to get pre-designed products is not because we cannot design but because we do not have enough experience and information to pre-select appropriate start ma terials and find right synthetic conditions. Therefore, the accumula tion of knowledge will lead to a greater extent to facilitate the de sign in the future. Nature does not respond to our questions randomly. The key is we should ask the “rig ht” questions. On the other hand, although supramolecular isomerism provides a number of possible topologies, these numbers are limited and they are actually predictable. In addition, although theoretically many t opologies are possible, actually only some of them are chemically feasible. Fo r example, there are fourteen possible twodimensional tilings of congruent pentagons only part of them can be realized by molecular solids. Insofar as, the design j ob is not as difficult as initially thought. In general, our strategy to the cont rol of topology from the metal organic supramolecular synthons provides a rational appr oach to the final goa l. It dramatically reduces the complicated situati on that it otherwise would be In addition, the research on the control and extending of nanoscaled Sec ondary Building Units gives us the potential functional materials that deserve further char acterization. They just open the door for the selection of promising candidates that may have significance in material science and technology.

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157 6.3. Future direction I believe that the general research direc tion in the field of crystal engineering is still the same: understanding intermolecula r interactions and searching for novel functional materials. Finding useful materi als by applying the pr inciples of crystal engineering lies in the center of this discipline. It requires more research targets for nanoscience and technology, a broad range of building units and the understanding of structure-function relationship. In my research project, future direct ions can be syntheses of isostructural compounds with different metal ions and car boxylic acid, or build ing new coordination polymers based on new metal-organic supramolecular synthons. These are currently undergoing in Dr. Zaworotko’s la b. However, the direction I wa nt to emphasize here is based on a new discovery of th e network topology of compound 6 6.3.1. A new interpretation of the network topology of compound 6 In Chapter 3, the connection of square SBUs as squares results in a topology that is a combination of rhombicuboctahedra, cube s and tetrahedra with a ratio of 1 : 1 : 2 (See Figure 3.10). However, if we regard the btc molecule as a triangle plane and SBUs as nodes, after linking the square nodes that are sitting around every trigonal center, this net topology is now changed in to an 8-connected net with cubic symmetry. It is now a combination of octahedral/cuboctahedra with a ratio of 1 : 1 as illustrated in Figure 6.1. This new interpretation illustrates that three of eleven possible arrangements319 of Platonic and Achimedean solids that tile sp ace (i.e. space-filing polyhedra) can be found in compounds 5 and 6 .

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158 ________________________________________________________________________ ________________________________________________________________________ Figure 6.1. Schematic representatio n of compound 6 with triangle

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159 ________________________________________________________________________ ________________________________________________________________________ Figure 6.2. Octahedral/cuboctahedra building units that are extracted from compound 6 Two new faceted polyhedra, tetrahemihexahedron and octahemioctahedron have been extracted from compound 6 (topology and molecular vers ion) as illustrated in Figure 6.2. The nodes of these faceted pol yhedra are all defined by SBUs. In tetrahemihexahedron half of the triangle faces are covered by btc molecules and the other half are open. In octahemioctahedron, all the triangle faces are covered by btc and all the square faces are open. It occurs to me that if two of the four ( cis ) directions of the square SBU could be terminated, these two faceted discrete polyhedra can be

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160 synthesized. This is the same design idea when btc is replaced with bdc. Actually, Cotton et al225 has reported an analogy of tetrahemihexahedron which is built from partially terminated square Mo-SBU and btc. However, octahemioctahedron, which also can be built from partially terminated SBU and btc, is still unknown. The separation distance betw een opposite faces of octa hemioctahedron is 1.88 nm and the dimension of the windows is about 0.9 nm. The effective interior diameter is 1.44 nm with effective volumes ca. 1.56 nm3. The separation distance between opposite faces of tetrahemihexahedron is 1.33 nm and the dimension of the windows is about 0.9 nm. The effective interior diameter is 0.94 nm, with effective volumes ca. 0.43 nm3. 6.3.2. Partially terminated square SBUs Partially terminated supramolecular s ynthons are not strange to us (See Figure 1.5). For example, metal ions such as Ni(II), Zn(II)or Cu(II), can be partially terminated by two nitrate ions into square or “T-shape” building blocks This building block can be further changed into an angular (90) ditopic building block.73 Other well-known examples of partially terminat ed supramolecular synthons are cis terminated Pt(II) and Pd(II) ions. They can serve as 90 ditopic bui lding units to build anionic polygons or polyhedra.124,320 Figure 6.3 illustrates that a partially te rminated square SBU could have four possible cases. The mono-terminated case is a perfect “T-shape”. The trans di-terminated case is a good linear spacer. Th e most important one is the cis terminated case, which, in principle, is a 90 angle linker for carboxylates. I believe that cis di-terminated square

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161 SBU have the same ability as does cis di-terminated Pt (II) or Pd (II) ion. Some Rh(II) analogues in this research di rection have been reported.321,322 ________________________________________________________________________ ______________________________________________________________________________________ Figure 6.3. Four possible cases of the partially terminated square SBU 6.4. Some pre-designed structures Besides the cuboctahedra structure (F igure 6.2), Figure 6.4 illustrates other possible structures that can be built from the partially terminated square SBU. They are all basic building units from the compounds described in Chap ter 4. The striking feature of all these structures is that they are all na no-scale discrete archite ctures. They may have potential applications such as hos t/guest chemistry or catalysis. Discrete structures that ar e constructed from square SBU and ditopic amines are also of interest. Figure 6.5 illustrates two examples of pre-designed discrete polygons, triangle and hexagon, that could be built from linear SBU and angular ditopic amines.

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162 ________________________________________________________________________ Figure 6.4. Six pre-designed structures based upon the partially terminated square SBU ______________________________________________________________________________________ Figure 6.5. Two examples of possi ble structures that can be built from linear spacer and angular ditopic amines

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163 6.5. The last words Chemists can reach nano scale region by “bottom-up” approach. This method enables chemists the ability to manipulate the topology of supramolecular assemblies, and subsequently their properties. This is a convenient alternate appr oach to the direction of the increase of molecular complexity, and it is also a practice of Richard Feynman’s dream of arranging atoms. The control of molecular arrangements in solid state relies on the control of intermolecular interactions. One of the goals of this work is to show that control by building predictable networks based on delib erately selected supr amolecular synthons. Although it is still hard to comp letely predict the final struct ure, it is obvious that the more knowledge we gain from research, the better we can do it.

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180 306. Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi, A. Chem. Commun. 1996 1393. 307. Abrahams, B. F.; Batten, S. R.; Hamit, H.; Hoskins, B. F.; Robson, R. Chem. Commun. 1996 1313. 308. Kepert, C. J.; Rosseinsky, M. J. Chem. Commun. 1998 31. 309. Russell, V. M.; Craig, D. C.; Scudder M. L.; Dance, I. G. CrystEngComm 2000 3. 310. Bu, X. H.; Chen, W.; Du, M.; Bi radha, K.; Wang, W. Z.; Zhang, R. H. Inorg. Chem. 2002 41 437-+. 311. Bu, X. H.; Biradha, K.; Yamaguchi, T.; Nishimura, M.; Ito, T.; Tanaka, K.; Shionoya, M. Chem. Commun. 2000 1953. 312. Decurtins, S.; Schmalle, H. W.; Schneuwly, P.; Ensling, J.; Gutlich, P. J. Am. Chem. Soc. 1994 116 9521. 313. Kheradmandan, S.; Schmalle, H. W.; Jacobsen, H.; Blacque, O.; Fox, T.; Berke, H.; Gross, M.; Decurtins, S. Chem. Eur. J. 2002 8 2526. 314. Abrahams, B. E.; Jackson, P. A.; Robson, R. Angew. Chem., Int. Ed. Engl. 1998 37 2656. 315. Kepert, C. J.; Prior, T. J.; Rosseinsky, M. J. J. Am. Chem. Soc. 2000 122 5158. 316. Batten, S. R. CrystEngComm 2001 art. no.-18. 317. Eddaoudi, M.; Moler, D. B.; Li, H. L.; Chen, B. L.; Reineke, T. M.; O'keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2001 34 319. 318. Niekerk J. N.; Schoening F. R. L. Acta Crystallogr. 1953 6 227. 319. Wells, D. The Penguin Dictionary of Curi ous and Interesting Geometry; Penguin: London, 1991. 320. Fujita, M.; Umemoto, K.; Yoshizawa, M.; Fujita, N.; Kusukawa, T.; Biradha, K. Chem. Commun. 2001 509. 321. Cotton, F. A.; Lin, C.; Murillo, C. A. Acc. Chem. Res. 2001 34 759. 322. Bickley, J. F.; Bonar-Law, R. P.; Femoni, C.; MacLean, E. J.; Steiner, A.; Teat, S. J. Dalton Trans. 2000 4025.

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181 A A p p p p e e n n d d i i c c e e s s

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182 A A p p p p e e n n d d i i x x A A 1 1 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 Identification code jl7231 Empirical formula C18 H14 N2 O4 Zn Formula weight 387.68 Temperature 173(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 9.0833(10) = 67.209(2). b = 10.1744(11) = 74.990(2). c = 10.2319(12) = 72.236(2). Volume 819.46(16) 3 Z 2 Density (calculated) 1.571 Mg/m3 Absorption coefficient 1.524 mm-1 F(000) 396 Crystal size 0.30 x 0.20 x 0.05 mm3 Theta range for data coll ection 2.19 to 28.71. Index ranges -11<=h<=12, -10<=k<=13, -7<=l<=13 Reflections collected 5441 Independent reflections 3754 [R(int) = 0.0297] Completeness to theta = 28.71 88.7 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3754 / 0 / 226 Goodness-of-fit on F2 0.830 Final R indices [I>2sigma(I)] R1 = 0.0417, wR2 = 0.0690 R indices (all data) R1 = 0.0591, wR2 = 0.0729 Largest diff. peak and hole 0.543 and -0.510 e.-3

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183 A A p p p p e e n n d d i i x x A A 2 2 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 2 2 Identification code jl7181 Empirical formula C24 H20 N3 O7.50 Zn1.50 Formula weight 568.48 Temperature 173(2) K Wavelength 0.71073 Crystal system Monoclinic Space group I2/a Unit cell dimensions a = 16.7655(15) = 90. b = 15.5285(14) = 93.623(2). c = 17.9717(16) = 90. Volume 4669.5(7) 3 Z 8 Density (calculated) 1.617 Mg/m3 Absorption coefficient 1.607 mm-1 F(000) 2320 Crystal size 0.1 x 0.2 x 0.2 mm3 Theta range for data coll ection 1.73 to 28.95. Index ranges -22<=h<=21, -20<=k<=13, -24<=l<=24 Reflections collected 15306 Independent reflections 5636 [R(int) = 0.0384] Completeness to theta = 28.95 90.9 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5636 / 0 / 318 Goodness-of-fit on F2 0.984 Final R indices [I>2sigma(I)] R1 = 0.0430, wR2 = 0.1049 R indices (all data) R1 = 0.0630, wR2 = 0.1211 Largest diff. peak and hole 1.231 and -0.804 e.-3

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184 A A p p p p e e n n d d i i x x A A 3 3 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 3 3 a a Identification code jl8504 Empirical formula C35 H31 N2 O4 Zn Formula weight 608.99 Temperature 173(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 9.6724(10) = 90. b = 20.217(2) = 93.545(2). c = 14.9774(15) = 90. Volume 2923.2(5) 3 Z 4 Density (calculated) 1.384 Mg/m3 Absorption coefficient 0.883 mm-1 F(000) 1268 Crystal size 0.1 x 0.1 x 0.3 mm3 Theta range for data coll ection 2.34 to 25.01. Index ranges -11<=h<=10, -23<=k<=23, -17<=l<=15 Reflections collected 13758 Independent reflections 5078 [R(int) = 0.0539] Completeness to theta = 25.01 98.5 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5078 / 0 / 380 Goodness-of-fit on F2 0.820 Final R indices [I>2sigma(I)] R1 = 0.0409, wR2 = 0.0751 R indices (all data) R1 = 0.0685, wR2 = 0.0800 Extinction coefficient 0.00000(15) Largest diff. peak and hole 0.751 and -0.480 e.-3

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185 A A p p p p e e n n d d i i x x A A 4 4 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 3 3 b b Identification code jl7301 Empirical formula C32 H21 N4 O7.50 Zn Formula weight 646.90 Temperature 173(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 10.5457(15) = 90. b = 18.400(3) = 90.971(3). c = 15.209(2) = 90. Volume 2950.8(7) 3 Z 4 Density (calculated) 1.456 Mg/m3 Absorption coefficient 0.890 mm-1 F(000) 1324 Crystal size 0.1 x 0.15 x 0.3 mm3 Theta range for data coll ection 1.74 to 26.42. Index ranges -13<=h<=10, -21<=k<=22, -19<=l<=19 Reflections collected 17360 Independent reflections 6038 [R(int) = 0.0896] Completeness to theta = 26.42 99.6 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6038 / 0 / 424 Goodness-of-fit on F2 0.817 Final R indices [I>2sigma(I)] R1 = 0.0591, wR2 = 0.1280 R indices (all data) R1 = 0.1403, wR2 = 0.1491 Largest diff. peak and hole 0.613 and -0.365 e.-3

PAGE 208

186 A A p p p p e e n n d d i i x x A A 5 5 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 3 3 c c Identification code jl8107 Empirical formula C27 H21.50 N2 O4.50 Zn Formula weight 511.33 Temperature 293(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 10.243(3) = 90. b = 18.317(5) = 91.116(5). c = 15.391(4) = 90. Volume 2887.3(13) 3 Z 4 Density (calculated) 1.176 Mg/m3 Absorption coefficient 0.882 mm-1 F(000) 1054 Crystal size .05 x .2 x .4 mm3 Theta range for data coll ection 1.73 to 23.32. Index ranges -11<=h<=10, -20<=k<=20, -16<=l<=16 Reflections collected 11482 Independent reflections 4129 [R(int) = 0.0862] Completeness to theta = 23.32 98.5 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4129 / 0 / 380 Goodness-of-fit on F2 0.934 Final R indices [I>2sigma(I)] R1 = 0.0739, wR2 = 0.1947 R indices (all data) R1 = 0.1463, wR2 = 0.2257 Largest diff. peak and hole 0.660 and -0.616 e.-3

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187 A A p p p p e e n n d d i i x x A A 6 6 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 3 3 d d Identification code jl8106 Empirical formula C32 H20 N2 O6 Zn Formula weight 593.87 Temperature 173(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 10.437(2) = 90. b = 18.516(4) = 90.119(4). c = 15.190(3) = 90. Volume 2935.6(10) 3 Z 4 Density (calculated) 1.344 Mg/m3 Absorption coefficient 0.882 mm-1 F(000) 1216 Crystal size .05 x .05 x .3 mm3 Theta range for data coll ection 1.73 to 25.02. Index ranges -12<=h<=12, -22<=k<=19, -13<=l<=18 Reflections collected 13859 Independent reflections 5165 [R(int) = 0.1018] Completeness to theta = 25.02 99.7 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5165 / 0 / 364 Goodness-of-fit on F2 0.847 Final R indices [I>2sigma(I)] R1 = 0.0722, wR2 = 0.1973 R indices (all data) R1 = 0.1547, wR2 = 0.2282 Largest diff. peak and hole 0.980 and -0.480 e.-3

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188 A A p p p p e e n n d d i i x x A A 7 7 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 3 3 e e Identification code jl9235 Empirical formula C31.50 H24 N2 O8 Zn Formula weight 623.90 Temperature 173(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2(1)/n Unit cell dimensions a = 10.5454(13) = 90. b = 20.202(2) = 96.781(2). c = 14.2392(17) = 90. Volume 3012.3(6) 3 Z 4 Density (calculated) 1.376 Mg/m3 Absorption coefficient 0.868 mm-1 F(000) 1284 Crystal size 0.2 x 0.2 x 0.4 mm3 Theta range for data coll ection 1.76 to 28.80. Index ranges -13<=h<=14, -26<=k<=27, -12<=l<=18 Reflections collected 17394 Independent reflections 7141 [R(int) = 0.0505] Completeness to theta = 28.80 90.7 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7141 / 0 / 398 Goodness-of-fit on F2 0.902 Final R indices [I>2sigma(I)] R1 = 0.0476, wR2 = 0.1144 R indices (all data) R1 = 0.0779, wR2 = 0.1295 Largest diff. peak and hole 0.787 and -0.362 e.-3

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189 A A p p p p e e n n d d i i x x A A 8 8 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 4 4 a a Identification code jl10142 Empirical formula C10.50 H9 Cl N O2 Zn0.50 Formula weight 249.32 Temperature 173(2) K Wavelength 0.71073 Crystal system Orthorhombic Space group Pnna Unit cell dimensions a = 10.0200(10) = 90. b = 15.1945(15) = 90. c = 13.6885(13) = 90. Volume 2084.1(4) 3 Z 8 Density (calculated) 1.589 Mg/m3 Absorption coefficient 1.466 mm-1 F(000) 1016 Crystal size 0.3 x 0.4 x 0.5 mm3 Theta range for data coll ection 2.00 to 26.40. Index ranges -7<=h<=12, -19<=k<=17, -17<=l<=16 Reflections collected 11306 Independent reflections 2151 [R(int) = 0.0304] Completeness to theta = 26.40 100.0 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2151 / 0 / 138 Goodness-of-fit on F2 1.106 Final R indices [I>2sigma(I)] R1 = 0.0444, wR2 = 0.1144 R indices (all data) R1 = 0.0483, wR2 = 0.1164 Largest diff. peak and hole 0.720 and -0.579 e.-3

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190 A A p p p p e e n n d d i i x x A A 9 9 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 4 4 b b Identification code jl8109 Empirical formula C10.50 H8 N O2.50 Zn0.50 Formula weight 220.86 Temperature 173(2) K Wavelength 0.71073 Crystal system Orthorhombic Space group Pnna Unit cell dimensions a = 9.676(3) = 90. b = 15.470(5) = 90. c = 13.547(5) = 90. Volume 2027.9(12) 3 Z 8 Density (calculated) 1.447 Mg/m3 Absorption coefficient 1.245 mm-1 F(000) 904 Crystal size .05 x .05 x .3 mm3 Theta range for data coll ection 2.00 to 25.00. Index ranges -10<=h<=10, -18<=k<=14, -16<=l<=7 Reflections collected 4424 Independent reflections 1740 [R(int) = 0.0659] Completeness to theta = 25.00 97.0 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 1740 / 0 / 138 Goodness-of-fit on F2 0.832 Final R indices [I>2sigma(I)] R1 = 0.0466, wR2 = 0.0982 R indices (all data) R1 = 0.1032, wR2 = 0.1261 Largest diff. peak and hole 0.601 and -0.496 e.-3

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191 A A p p p p e e n n d d i i x x A A 1 1 0 0 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 5 5 Identification code jl7164 Empirical formula C182 H36 N42 O72 Zn22 Formula weight 5400.67 Temperature 173(2) K Wavelength 0.71073 Crystal system Cubic Space group Pm-3m Unit cell dimensions a = 20.4702(11) = 90. b = 20.4702(11) = 90. c = 20.4702(11) = 90. Volume 8577.6(8) 3 Z 1 Density (calculated) 1.046 Mg/m3 Absorption coefficient 1.565 mm-1 F(000) 2658 Crystal size 0.30 x 0.30 x 0.15 mm3 Theta range for data coll ection 0.99 to 18.00. Index ranges -17<=h<=15, -6<=k<=17, -17<=l<=17 Reflections collected 12984 Independent reflections 654 [R(int) = 0.0379] Completeness to theta = 18.00 99.7 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 654 / 0 / 85 Goodness-of-fit on F2 1.769 Final R indices [I>2sigma(I)] R1 = 0.1457, wR2 = 0.3763 R indices (all data) R1 = 0.1593, wR2 = 0.3945 Largest diff. peak and hole 1.076 and -0.984 e.-3

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192 A A p p p p e e n n d d i i x x A A 1 1 1 1 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 6 6 Identification code jl7201 Empirical formula C27.83 H4 O10 Zn2 Formula weight 629.05 Temperature 293(2) K Wavelength 0.71073 Crystal system Cubic Space group Fm-3m Unit cell dimensions a = 26.5367(13) = 90. b = 26.5367(13) = 90. c = 26.5367(13) = 90. Volume 18687.0(16) 3 Z 24 Density (calculated) 1.342 Mg/m3 Absorption coefficient 1.588 mm-1 F(000) 7464 Crystal size 0.30 x 0.25 x 0.20 mm3 Theta range for data coll ection 1.33 to 26.01. Index ranges -32<=h<=32, -32<=k<=18, -28<=l<=32 Reflections collected 24683 Independent reflections 981 [R(int) = 0.0610] Completeness to theta = 26.01 100.0 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 981 / 0 / 53 Goodness-of-fit on F2 1.047 Final R indices [I>2sigma(I)] R1 = 0.0647, wR2 = 0.1784 R indices (all data) R1 = 0.0778, wR2 = 0.1897 Largest diff. peak and hole 0.733 and -0.723 e.-3

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193 A A p p p p e e n n d d i i x x A A 1 1 2 2 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 7 7 a a Identification code Jl2113 (cu2nb3) Empirical formula C245.84 H96 Cu24 O120 Formula weight 6494.21 Temperature 200(2) K Wavelength 0.71073 Crystal system Cubic Space group Im-3m Unit cell dimensions a = 27.6895(17) = 90. b = 27.6895(17) = 90. c = 27.6895(17) = 90. Volume 21230(2) 3 Z 2 Density (calculated) 1.016 Mg/m3 Absorption coefficient 1.235 mm-1 F(000) 6454 Crystal size .1 x .1 x .3 mm3 Theta range for data coll ection 2.75 to 23.25. Index ranges -30<=h<=27, -26<=k<=30, -29<=l<=30 Reflections collected 36316 Independent reflections 1501 [R(int) = 0.0865] Completeness to theta = 23.25 99.6 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 1501 / 0 / 100 Goodness-of-fit on F2 1.138 Final R indices [I>2sigma(I)] R1 = 0.0784, wR2 = 0.2725 R indices (all data) R1 = 0.1069, wR2 = 0.2953 Largest diff. peak and hole 0.831 and -0.438 e.-3

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194 A A p p p p e e n n d d i i x x A A 1 1 3 3 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 7 7 b b Identification code jl12297 Empirical formula C264 Cu24 N12 O108 Formula weight 6797.62 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 26.202(9) = 92.583(5). b = 27.756(10) = 96.393(5). c = 28.407(10) = 92.643(5). Volume 20483(12) 3 Z 2 Density (calculated) 1.279 Mg/m3 Absorption coefficient 1.291 mm-1 F(000) 7752 Crystal size .15 x .10 x .10 mm3 Theta range for data coll ection 3.72 to 18.94. Index ranges -23<=h<=23, -25<=k<=25, -25<=l<=20 Reflections collected 45871 Independent reflections 31316 [R(int) = 0.1340] Completeness to theta = 18.94 95.9 % Absorption correction SADABS Refinement method Full-matrix-block least-squares on F2 Data / restraints / parameters 31316 / 0 / 2529 Goodness-of-fit on F2 1.089 Final R indices [I>2sigma(I)] R1 = 0.1379, wR2 = 0.3499 R indices (all data) R1 = 0.2849, wR2 = 0.4223 Largest diff. peak and hole 0.940 and -0.510 e.-3

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195 A A p p p p e e n n d d i i x x A A 1 1 4 4 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 8 8 Identification code jl12263 Empirical formula C18 H10 Cu N O5 Formula weight 383.81 Temperature 173(2) K Wavelength 0.71073 Crystal system Tetragonal Space group P4/ncc Unit cell dimensions a = 18.7912(8) = 90. b = 18.7912(8) = 90. c = 16.8886(10) = 90. Volume 5963.5(5) 3 Z 16 Density (calculated) 1.924 Mg/m3 Absorption coefficient 1.683 mm-1 F(000) 3492 Crystal size .1 x .1 x .2 mm3 Theta range for data coll ection 1.53 to 28.27. Index ranges -23<=h<=24, -20<=k<=25, -21<=l<=22 Reflections collected 33929 Independent reflections 3632 [R(int) = 0.0560] Completeness to theta = 28.27 97.9 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3632 / 0 / 231 Goodness-of-fit on F2 0.866 Final R indices [I>2sigma(I)] R1 = 0.0407, wR2 = 0.1063 R indices (all data) R1 = 0.0680, wR2 = 0.1139 Largest diff. peak and hole 0.926 and -0.523 e.-3

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196 A A p p p p e e n n d d i i x x A A 1 1 5 5 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 9 9 Identification code jl25227 Empirical formula C34 H26 Cl2 Cu2 N2 O8 Formula weight 788.55 Temperature 100(2) K Wavelength 0.71073 Crystal system Monoclinic Space group Cc Unit cell dimensions a = 19.5148(14) = 90. b = 12.7678(9) = 114.1330(10). c = 14.3466(10) = 90. Volume 3262.2(4) 3 Z 4 Density (calculated) 1.606 Mg/m3 Absorption coefficient 1.523 mm-1 F(000) 1600 Crystal size 0.10 x 0.10 x 0.05 mm3 Theta range for data coll ection 1.96 to 28.29. Index ranges -25<=h<=25, -14<=k<=17, -15<=l<=18 Reflections collected 10312 Independent reflections 6730 [R(int) = 0.0332] Completeness to theta = 28.29 95.2 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6730 / 2 / 435 Goodness-of-fit on F2 1.033 Final R indices [I>2sigma(I)] R1 = 0.0453, wR2 = 0.1011 R indices (all data) R1 = 0.0529, wR2 = 0.1063 Absolute structure parameter 0.485(15) Largest diff. peak and hole 0.663 and -0.335 e.-3

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197 A A p p p p e e n n d d i i x x A A 1 1 6 6 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 0 0 Identification code jl2581 Empirical formula C22 H16 Cu2 O10 S4 Formula weight 695.67 Temperature 200(2) K Wavelength 0.71073 Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 15.637(4) = 90. b = 15.430(4) = 116.692(4). c = 13.332(3) = 90. Volume 2874.1(13) 3 Z 4 Density (calculated) 1.608 Mg/m3 Absorption coefficient 1.820 mm-1 F(000) 1400 Crystal size 0.10 x 0.10 x 0.02 mm3 Theta range for data coll ection 1.97 to 28.30. Index ranges -20<=h<=19, -20<=k<=20, -9<=l<=16 Reflections collected 8435 Independent reflections 3360 [R(int) = 0.0848] Completeness to theta = 28.30 93.9 % Absorption correction SADABS Max. and min. transmission 1.000 and 0.807 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3360 / 0 / 192 Goodness-of-fit on F2 1.024 Final R indices [I>2sigma(I)] R1 = 0.0767, wR2 = 0.1539 R indices (all data) R1 = 0.1229, wR2 = 0.1709 Largest diff. peak and hole 1.785 and -0.647 e.-3

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198 A A p p p p e e n n d d i i x x A A 1 1 7 7 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 1 1 a a Identification code Jl0122 Empirical formula C20 H20 Cu N O5 Formula weight 417.91 Temperature 173(2) K Wavelength 0.71073 Crystal system Trigonal Space group P-3c1 Unit cell dimensions a = 18.6331(11) = 90. b = 18.6331(11) = 90. c = 19.8107(17) = 120. Volume 5956.6(7) 3 Z 12 Density (calculated) 1.398 Mg/m 3 Absorption coefficient 1.129 mm -1 F(000) 2592 Crystal size 0.20 x 0.10 x 0.10 mm 3 Theta range for data coll ection 2.19 to 28.25. Index ranges -24<=h<=19, -16<=k<=24, -26<=l<=25 Reflections collected 34892 Independent reflections 4826 [R(int) = 0.0565] Completeness to theta = 28.25 97.9 % Absorption correction SADABS Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 4826 / 0 / 236 Goodness-of-fit on F 2 0.714 Final R indices [I>2sigma(I)] R1 = 0.0588, wR2 = 0.2010 R indices (all data) R1 = 0.0995, wR2 = 0.2275 Largest diff. peak and hole 1.055 and -0.806 e. -3

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199 A A p p p p e e n n d d i i x x A A 1 1 8 8 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 1 1 b b Identification code jl8301 Empirical formula C46.67 H40 Cu2 N4 O15.33 Formula weight 1029.24 Temperature 200(2) K Wavelength 0.71073 Crystal system Trigonal Space group P-3 Unit cell dimensions a = 18.8573(12) = 90. b = 18.8573(12) = 90. c = 12.7135(12) = 120. Volume 3915.2(5) 3 Z 3 Density (calculated) 1.310 Mg/m3 Absorption coefficient 0.881 mm-1 F(000) 1586 Crystal size 0.02 x 0.1 x 0.1 mm3 Theta range for data coll ection 1.60 to 27.00. Index ranges -23<=h<=24, -24<=k<=22, -14<=l<=16 Reflections collected 23416 Independent reflections 5701 [R(int) = 0.1437] Completeness to theta = 27.00 100.0 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5701 / 0 / 379 Goodness-of-fit on F2 1.085 Final R indices [I>2sigma(I)] R1 = 0.1072, wR2 = 0.3219 R indices (all data) R1 = 0.1807, wR2 = 0.3445 Largest diff. peak and hole 0.829 and -0.912 e.-3

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200 A A p p p p e e n n d d i i x x A A 1 1 9 9 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 2 2 Identification code jl8132 Empirical formula C34 H22 Cu2 N2 O8 Formula weight 713.62 Temperature 200(2) K Wavelength 0.71073 Crystal system Rhombohedral Space group R-3c Unit cell dimensions a = 30.337(2) = 90. b = 30.337(2) = 90. c = 18.380(2) = 120. Volume 14649(2) 3 Z 18 Density (calculated) 1.456 Mg/m3 Absorption coefficient 1.359 mm-1 F(000) 6516 Crystal size 0.02 x 0.05 x 0.1 mm3 Theta range for data coll ection 1.34 to 23.26. Index ranges -33<=h<=33, -33<=k<=30, -20<=l<=11 Reflections collected 18919 Independent reflections 2352 [R(int) = 0.1775] Completeness to theta = 23.26 99.7 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2352 / 0 / 243 Goodness-of-fit on F2 0.841 Final R indices [I>2sigma(I)] R1 = 0.0497, wR2 = 0.1137 R indices (all data) R1 = 0.1205, wR2 = 0.1630 Largest diff. peak and hole 0.994 and -0.396 e.-3

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201 A A p p p p e e n n d d i i x x A A 2 2 0 0 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 a a Identification code jl21302 Empirical formula C40 H32 Cu2 N2 O8.80 Formula weight 808.56 Temperature 200(2) K Wavelength 0.71073 Crystal system Monoclinic Space group C2/m Unit cell dimensions a = 10.458(2) = 90. b = 18.489(4) = 104.753(4). c = 9.993(2) = 90. Volume 1868.6(7) 3 Z 2 Density (calculated) 1.437 Mg/m3 Absorption coefficient 1.195 mm-1 F(000) 829 Crystal size 0.20 x 0.05 x 0.05 mm3 Theta range for data coll ection 2.11 to 28.32. Index ranges -13<=h<=10, -24<=k<=24, -13<=l<=11 Reflections collected 5749 Independent reflections 2251 [R(int) = 0.0320] Completeness to theta = 28.32 93.9 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2251 / 0 / 134 Goodness-of-fit on F2 1.056 Final R indices [I>2sigma(I)] R1 = 0.0900, wR2 = 0.2488 R indices (all data) R1 = 0.1115, wR2 = 0.2694 Largest diff. peak and hole 1.027 and -0.911 e.-3

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202 A A p p p p e e n n d d i i x x A A 2 2 1 1 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 b b Identification code jl21152 Empirical formula C47 H40 Cu2 N2 O9 Formula weight 903.89 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 10.4099(8) = 74.7720(10). b = 10.9301(8) = 75.5240(10). c = 19.8827(15) = 76.9480(10). Volume 2082.3(3) 3 Z 2 Density (calculated) 1.442 Mg/m3 Absorption coefficient 1.081 mm-1 F(000) 932 Crystal size 0.20 x 0.20 x 0.10 mm3 Theta range for data coll ection 1.08 to 28.28. Index ranges -13<=h<=13, -14<=k<=14, -26<=l<=25 Reflections collected 18283 Independent reflections 9482 [R(int) = 0.0308] Completeness to theta = 28.28 91.6 % Absorption correction SADABS Max. and min. transmission 1.000 and 0.820 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9482 / 0 / 542 Goodness-of-fit on F2 1.035 Final R indices [I>2sigma(I)] R1 = 0.0433, wR2 = 0.1073 R indices (all data) R1 = 0.0568, wR2 = 0.1141 Largest diff. peak and hole 0.807 and -0.327 e.-3

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203 A A p p p p e e n n d d i i x x A A 2 2 2 2 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 c c Identification code jl2129 Empirical formula C48 H42 Cu2 N2 O8 Formula weight 901.92 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 9.943(2) = 99.743(4). b = 10.216(2) = 97.904(5). c = 11.118(3) = 107.601(4). Volume 1039.3(4) 3 Z 1 Density (calculated) 1.441 Mg/m3 Absorption coefficient 1.081 mm-1 F(000) 466 Crystal size 0.10 x 0.10 x 0.01 mm3 Theta range for data coll ection 1.90 to 28.28. Index ranges -12<=h<=12, -11<=k<=13, -14<=l<=13 Reflections collected 6379 Independent reflections 4596 [R(int) = 0.0413] Completeness to theta = 28.28 89.0 % Absorption correction SADABS Max. and min. transmission 1.00 and 0.807 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4596 / 0 / 272 Goodness-of-fit on F2 1.085 Final R indices [I>2sigma(I)] R1 = 0.0832, wR2 = 0.2262 R indices (all data) R1 = 0.1339, wR2 = 0.2499 Largest diff. peak and hole 1.246 and -0.631 e.-3

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204 A A p p p p e e n n d d i i x x A A 2 2 3 3 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 d d Identification code jl21292 Empirical formula C48 H42 Cu2 N2 O8 Formula weight 901.92 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 9.987(2) = 97.770(3). b = 10.085(2) = 98.563(3). c = 11.104(2) = 107.883(3). Volume 1032.8(4) 3 Z 1 Density (calculated) 1.450 Mg/m3 Absorption coefficient 1.088 mm-1 F(000) 466 Crystal size 0.20 x 0.20 x 0.01 mm3 Theta range for data coll ection 1.89 to 28.32. Index ranges -13<=h<=12, -12<=k<=13, -14<=l<=14 Reflections collected 9079 Independent reflections 4714 [R(int) = 0.0453] Completeness to theta = 28.32 91.4 % Absorption correction SADABS Max. and min. transmission 1.00 and 0.646 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4714 / 0 / 272 Goodness-of-fit on F2 1.049 Final R indices [I>2sigma(I)] R1 = 0.0612, wR2 = 0.1547 R indices (all data) R1 = 0.0754, wR2 = 0.1638 Largest diff. peak and hole 1.768 and -1.087 e.-3

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205 A A p p p p e e n n d d i i x x A A 2 2 4 4 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 e e Identification code jl1221a Empirical formula C26 H21 Cu N2 O6 Formula weight 520.99 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 8.1454(12) = 78.398(2). b = 12.1913(17) = 88.018(2). c = 12.3830(18) = 75.468(2). Volume 1165.8(3) 3 Z 2 Density (calculated) 1.484 Mg/m3 Absorption coefficient 0.982 mm-1 F(000) 536 Crystal size 0.01 x 0.1 x 0.2 mm3 Theta range for data coll ection 1.68 to 28.30. Index ranges -10<=h<=10, -16<=k<=16, -16<=l<=16 Reflections collected 10240 Independent reflections 5303 [R(int) = 0.0342] Completeness to theta = 28.30 91.3 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5303 / 0 / 325 Goodness-of-fit on F2 0.957 Final R indices [I>2sigma(I)] R1 = 0.0522, wR2 = 0.1224 R indices (all data) R1 = 0.0717, wR2 = 0.1332 Largest diff. peak and hole 0.648 and -0.410 e.-3

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206 A A p p p p e e n n d d i i x x A A 2 2 5 5 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 f f Identification code jl22182 Empirical formula C26 H16 Cl2 Cu N O4 Formula weight 540.84 Temperature 200(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 8.4456(11) = 74.784(2). b = 11.9794(16) = 86.305(2). c = 12.6532(17) = 76.146(2). Volume 1199.3(3) 3 Z 2 Density (calculated) 1.498 Mg/m3 Absorption coefficient 1.166 mm-1 F(000) 548 Crystal size 0.02 x 0.1 x 0.15 mm3 Theta range for data coll ection 1.67 to 28.26. Index ranges -11<=h<=11, -15<=k<=15, -16<=l<=16 Reflections collected 10423 Independent reflections 5410 [R(int) = 0.0342] Completeness to theta = 28.26 91.1 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5410 / 0 / 325 Goodness-of-fit on F2 1.059 Final R indices [I>2sigma(I)] R1 = 0.0660, wR2 = 0.1682 R indices (all data) R1 = 0.0915, wR2 = 0.1834 Largest diff. peak and hole 1.242 and -0.705 e.-3

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207 A A p p p p e e n n d d i i x x A A 2 2 6 6 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 3 3 g g Identification code jl2115 Empirical formula C49 H41 Cu2 N2 O8 Formula weight 912.92 Temperature 293(2) K Wavelength 0.71073 Crystal system Triclinic Space group P-1 Unit cell dimensions a = 9.9683(12) = 100.970(2). b = 10.4761(13) = 94.743(2). c = 22.098(3) = 105.011(2). Volume 2166.9(5) 3 Z 2 Density (calculated) 1.399 Mg/m3 Absorption coefficient 1.038 mm-1 F(000) 942 Crystal size 0.40 x 0.10 x 0.05 mm3 Theta range for data coll ection 0.95 to 28.31. Index ranges -13<=h<=13, -13<=k<=13, -29<=l<=29 Reflections collected 18846 Independent reflections 9875 [R(int) = 0.0421] Completeness to theta = 28.31 91.5 % Absorption correction SADABS Max. and min. transmission 1.00 and 0.847 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9875 / 0 / 550 Goodness-of-fit on F2 1.152 Final R indices [I>2sigma(I)] R1 = 0.0765, wR2 = 0.2074 R indices (all data) R1 = 0.1071, wR2 = 0.2197 Largest diff. peak and hole 1.260 and -0.650 e.-3

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208 A A p p p p e e n n d d i i x x A A 2 2 7 7 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 4 4 Identification code jl21081 Empirical formula C19 H20 Cu N2 O6 Formula weight 435.91 Temperature 200(2) K Wavelength 0.71073 Crystal system Orthorhombic Space group Pbcn Unit cell dimensions a = 13.3918(11) = 90. b = 15.5991(13) = 90. c = 17.5774(14) = 90. Volume 3671.9(5) 3 Z 8 Density (calculated) 1.577 Mg/m3 Absorption coefficient 1.230 mm-1 F(000) 1800 Crystal size 0.02 x 0.05 x 0.2 mm3 Theta range for data coll ection 2.00 to 31.45. Index ranges -5<=h<=15, -9<=k<=22, -20<=l<=4 Reflections collected 5470 Independent reflections 3835 [R(int) = 0.0503] Completeness to theta = 31.45 62.9 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3835 / 0 / 256 Goodness-of-fit on F2 0.598 Final R indices [I>2sigma(I)] R1 = 0.0489, wR2 = 0.0994 R indices (all data) R1 = 0.1266, wR2 = 0.1237 Largest diff. peak and hole 0.556 and -0.588 e.-3

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209 A A p p p p e e n n d d i i x x A A 2 2 8 8 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 5 5 Identification code jl7141 Empirical formula C16 H12 Cu N3.33 O8 Formula weight 442.50 Temperature 200(2) K Wavelength 0.71073 Crystal system Trigonal Space group P-3 Unit cell dimensions a = 15.756(5) = 90. b = 15.756(5) = 90. c = 12.894(6) = 120. Volume 2772.0(18) 3 Z 6 Density (calculated) 1.590 Mg/m3 Absorption coefficient 1.233 mm-1 F(000) 1346 Crystal size 0.02 x 0.1 x 0.1 mm3 Theta range for data coll ection 1.58 to 28.30. Index ranges -15<=h<=15, -19<=k<=8, -3<=l<=16 Reflections collected 4463 Independent reflections 3211 [R(int) = 0.0802] Completeness to theta = 28.30 69.8 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3211 / 0 / 216 Goodness-of-fit on F2 0.803 Final R indices [I>2sigma(I)] R1 = 0.0760, wR2 = 0.2004 R indices (all data) R1 = 0.1932, wR2 = 0.2429 Largest diff. peak and hole 0.964 and -0.519 e.-3

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210 A A p p p p e e n n d d i i x x A A 2 2 9 9 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 6 6 Identification code jl04101 Empirical formula C20.50 H16 Cu2.50 N3 O10 Formula weight 623.21 Temperature 200(2) K Wavelength 0.71073 Crystal system Tetragonal Space group P-42(1)m Unit cell dimensions a = 22.9167(15) = 90. b = 22.9167(15) = 90. c = 10.7915(10) = 90. Volume 5667.4(7) 3 Z 8 Density (calculated) 1.461 Mg/m3 Absorption coefficient 1.917 mm-1 F(000) 2500 Crystal size .05 x .15 x .25 mm3 Theta range for data coll ection 1.26 to 23.29. Index ranges -21<=h<=25, -25<=k<=25, -11<=l<=12 Reflections collected 25447 Independent reflections 4240 [R(int) = 0.0919] Completeness to theta = 23.29 99.8 % Absorption correction None Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4240 / 0 / 321 Goodness-of-fit on F2 0.908 Final R indices [I>2sigma(I)] R1 = 0.0464, wR2 = 0.1015 R indices (all data) R1 = 0.0661, wR2 = 0.1220 Absolute structure parameter 0.04(3) Largest diff. peak and hole 0.511 and -0.396 e.-3

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211 A A p p p p e e n n d d i i x x A A 3 3 0 0 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 7 7 Identification code jl03124 Empirical formula C15.50 H13 Cu N O4 Formula weight 340.81 Temperature 200(2) K Wavelength 0.71073 Crystal system Tetragonal Space group I4(1)/a Unit cell dimensions a = 15.9763(16) = 90. b = 15.9763(16) = 90. c = 23.559(3) = 90. Volume 6013.1(12) 3 Z 16 Density (calculated) 1.506 Mg/m3 Absorption coefficient 1.468 mm-1 F(000) 2784 Crystal size 0.1 x 0.1 x 0.1 mm3 Theta range for data coll ection 1.54 to 28.21. Index ranges -13<=h<=16, -17<=k<=14, 1<=l<=30 Reflections collected 4574 Independent reflections 1569 [R(int) = 0.0588] Completeness to theta = 28.21 42.4 % Absorption correction None Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 1569 / 0 / 195 Goodness-of-fit on F2 0.792 Final R indices [I>2sigma(I)] R1 = 0.0339, wR2 = 0.0649 R indices (all data) R1 = 0.0565, wR2 = 0.0704 Largest diff. peak and hole 0.239 and -0.315 e.-3

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212 A A p p p p e e n n d d i i x x A A 3 3 1 1 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 8 8 a a Identification code jl008r Empirical formula C41 H76 Cu6 N12 O24 Formula weight 1502.38 Temperature 100(2) K Wavelength 0.71073 Crystal system Tetragonal Space group P4(2)/nbc Unit cell dimensions a = 20.531(2) = 90. b = 20.531(2) = 90. c = 13.554(3) = 90. Volume 5713.3(14) 3 Z 4 Density (calculated) 1.747 Mg/m3 Absorption coefficient 2.283 mm-1 F(000) 3088 Crystal size 0.20 x 0.05 x 0.05 mm3 Theta range for data coll ection 1.40 to 28.28. Index ranges -15<=h<=27, -26<=k<=26, -16<=l<=17 Reflections collected 32288 Independent reflections 3460 [R(int) = 0.0492] Completeness to theta = 28.28 97.2 % Absorption correction SADABS Max. and min. transmission 1.00 and 0.613 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3460 / 0 / 209 Goodness-of-fit on F2 1.274 Final R indices [I>2sigma(I)] R1 = 0.0940, wR2 = 0.2127 R indices (all data) R1 = 0.0978, wR2 = 0.2155 Largest diff. peak and hole 1.334 and -1.179 e.-3

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213 A A p p p p e e n n d d i i x x A A 3 3 2 2 . C C r r y y s s t t a a l l d d a a t t a a a a n n d d s s t t r r u u c c t t u u r r e e r r e e f f i i n n e e m m e e n n t t f f o o r r c c o o m m p p o o u u n n d d 1 1 8 8 b b Identification code jl6233 Empirical formula C72 H132 Cu6 N8 O24 Formula weight 1875.10 Temperature 200(2) K Wavelength 0.71073 Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 36.648(3) = 90. b = 28.129(2) = 133.6580(10). c = 26.131(2) = 90. Volume 19489(2) 3 Z 8 Density (calculated) 1.278 Mg/m3 Absorption coefficient 1.352 mm-1 F(000) 7888 Crystal size 0.1 x 0.1 x 0.2 mm3 Theta range for data coll ection 1.06 to 23.30. Index ranges -30<=h<=40, -31<=k<=31, -29<=l<=28 Reflections collected 42694 Independent reflections 14038 [R(int) = 0.1181] Completeness to theta = 23.30 99.8 % Absorption correction SADABS Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 14038 / 0 / 798 Goodness-of-fit on F2 0.759 Final R indices [I>2sigma(I)] R1 = 0.0644, wR2 = 0.1502 R indices (all data) R1 = 0.1543, wR2 = 0.1755 Largest diff. peak and hole 0.846 and -0.494 e.-3

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214 A A p p p p e e n n d d i i x x B B 1 1 4 4 t t y y p p e e s s o o f f p p e e n n t t a a g g o o n n p p e e r r i i o o d d i i c c a a l l t t i i l l t t i i n n g g Type 1 : D + E = 180 Type 2 : C + E = 180, a = d Type 3 : A = C = D = 120, a = b, d = c + e Type 4 : A = C = 90, a = b, c = d Type 5 : C = 2A = 120, a = b, c = d Type 6 : C + E = 180, A = 2C, a = b = e, c = d

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215 Type 7 : 2B + C = 360, 2D + A = 360, Type 8 : 2A + B = 360, 2D + C = 360, a = b = c = d a= b = c = d Type 9 : 2E + B = 360, 2D + C = 360, Type 10 : E = 90, A + D = 180, 2B D a = b = c = d = 180, 2C + D = 360, a = e = b + d Type 11 : A = 90, C + E = 180, 2B + C Type 12 : A = 90, C + E = 180, 2B + C = = 360, d = e = 2a + c 360, 2a = c + e = d

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216 Type 13 : A = C = 90, 2B = 2E = 360 D, c = d, 2c = e Type 14 : D = 90, 2E + A = 360, C + A = 180, B + D + E = 360, 2e = 2c = a

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A A b b o o u u t t t t h h e e A A u u t t h h o o r r Jianjiang Lu received his Bachelor’s degree in Chemistry from Zhejiang University, Hangzhou, China in 1991 and obtai ned his Master degree in Physical Chemistry from Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China in 1994. In 2000, Jianjiang joined Dr. Michael J. Zaworotko’s research group at the University of South Florida to pursue his Do ctoral Degree in Chemistry. While in the Ph.D. program, he was honored with the 2003 Askounes-Ashford Award for outstanding Ph.D. seeking graduate student in the De partment of Chemistry. Jianjiang has coauthored eight peer-reviewed publications, and has presented his rese arch at regional and national scientific meetings of the American Chemical Society.