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Toward the synthesis of designed metal-organic materials

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Title:
Toward the synthesis of designed metal-organic materials
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English
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Brant, Jacilynn A
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Metal-organic materials
Metal-organic frameworks
Coordination polymers
Molecular building blocks
Dissertations, Academic -- Chemistry -- Masters -- USF   ( lcsh )
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non-fiction   ( marcgt )

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Thesis (M.S.)--University of South Florida, 2008.
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Includes bibliographical references.
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by Jacilynn A. Brant.
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Coordination polymers
Molecular building blocks
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i Table of Contents List of Figures iv List of Abbreviations viii Abstract x Chapter 1: Introduction to Metal-Organic Materials 1 Overview of History 2 Fundamentals 7 Challenges 11 Advancements/Developments 11 Chapter 2: Introduction to Rational Synt hesis of Metal-Organic Materials 13 Overview 13 Fundamentals 14 Challenges 18 Advancements/Developments 19 Chapter 3: Single-Metal Ion-based Mol ecular Building Block Approaches for the Advancement of MetalOrganic Material Design 21 MNx(CO2)y Molecular Building Blocks Constructed from Nitrogenand Carboxylate based Heterochelating Ligands 21 MN4O2 Single Metal Ions in Mole cular Building Blocks 22 MN2O4 Building Units derived from MN2(CO2)4 Molecular Building Blocks 23 MN3O3 Building Units derived from MN3(CO2)3 Molecular Building Blocks 25

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ii Experimental 27 Results & Discussion 31 MOMs resulting from MN4O2 Single-metal ion-based Molecular Building Blocks 31 MOMs from MN2O4 Single-Metal Ion-based MBBs 34 MOMs Containing MN3O3 Building Units 39 Heterocoordinated Metal-Orga nic Frameworks from MBBs 40 Summary/Conclusions 43 Chapter 4: Design of Zeolitelike Metal-Organic Frameworks (ZMOFs) 45 ZMOFs from Supermolecular Building Blocks 47 Experimental 49 Results & Discussion 51 ZMOFs from MNx(CO2)y Molecular Building Blocks 52 Experimental 53 Results & Discussion 54 ZMOFs from Organic Tetrahedral Nodes 58 Experimental 60 Results & Discussion 63 Conclusions 66 Chapter 5: Conclusions and Future Outlook 67 References 70 Appendices 76 Appendix I: Crysta llography Tables 77

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iii Appendix II: Thermal Gravimetric Analysis 83 Appendix III: UV-Visible Spectroscopy 85

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iv List of Figures Figure 1.1 (a) Reaction of 4,4’-bipyridine with zinc ions yields2-D square grids that interpenetrate, and (b) individua l layers are shown in red, green, blue, and yellow. 3 Figure 1.2. The use of the paddlewheel cluste r as a 6-connected node is illustrated, as 4,4’-bipyridine bridges axial positions. 5 Figure 1.3. The basic zinc acetate cluster (left) composed of four tetrahedral metal ions coordinated by six carbox ylates to form a 6-coordinate node,that is used to construct various IRMOFs with analogous topology to CaB6 (right). 6 Figure 1.4. a) Neutral, b) cationic, and c) anionic ligan ds can be used in the synthesis of MOFs with varying ionic strengths. 7 Figure 1.5. 0-, 1-, 2-, 3-D (left to right) metal-organic materials depicted with nodes (green) and spacers (blue). 8 Figure 1.6. The coordination se quence (4, 9, 17, 28, 42, 60, 81, 105, 132, 162) and vertex symbol (4.6.4.6.4.8) of the lta net are displayed. 9 Figure 1.7. The lta net contains three types of tiles [46] (blue), [46.68] (yellow), and [412.68.86] (red). 10 Figure 2.1. Regular, quasi -regular, and semi-regular nets, classified by transitivity, are prime targets fo r the synthesis of pre-designed networks. 14 Figure 2.2. Edge transitive, binodal nets re present a class of lucrative nets to target. 15 Figure 2.3. The rho net can be intellectively disman tled to essential tetrahedral building units linked through an approximate 145 angle and consequently rebuilt and expanded using metal-organic molecular building blocks (MBBs). 17 Figure 2.4. 4,5-IMDC and In3+ are used to make a TBU for the assembly of anionic rhoZMOF. 18

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v Figure 2.5. A MN3(CO2)3 MBB, from a heterochelat ing ligand, (center) has a rigid geometry, while the N-based building block (left) and paddlewheel building block (right) show the potential for bond rotations. 20 Figure 3.1. (Left) Heterochelating ligands with bridging functionality: (a) 4-imidazolecarboxylic acid, (b ) 4,5-imidazoledi carboxylic acid, (c) 4-imidazolethanoate, (d) 2,4pyridinedicarboxylic acid, (e) 2,5-pyridinedicarboxylic aci d, and (f) 4,6-pyrimid inedicarboxylic acid. (Right) Isomers of MNxOy single metal ions. 21 Figure 3.2. MN4O2 single metal ions can be used to access seesawand square planar-like building units. 22 Figure 3.3. Heterochelating lig ands can coordinate to sing le-metal ions to result in MN2(CO2)4 molecular building blocks that act as 4-connected square-planarand see-sawlike building units. 23 Figure 3.4. MN2(CO2)4 MBBs are used to construc t a metal organic Kagom lattice, an octahedr on, and diamond-like net. 25 Figure 3.5. MN3(CO2)3 molecular building blocks can be viewed as fac(top) or merMN3O3 (bottom) building units. 26 Figure 3.6. A metal-organic c ube is constructed from a facNiN3(CO2)3 MBB. 26 Figure 3.7. Two types of 2-connected MBBs combine to form zig-zag chains in ME089. 32 Figure 3.8. Doubly interpenetrated uoc nets are constructed from a MN4O2 single-metal ion-based MBB, consisting of cadmium, 4,5-imidazolecarboxylate, and ethylenediamine. 33 Figure 3.9. ME184, of dia topology, is constructed from a tetrahedral CdN4 building block. 34 Figure 3.10. [In6(2,5-PDC)12]6 consists of 4-connected MBBs with the formula MN2(CO2)4. 35 Figure 3.11. ME096 consists of zig-zag chai ns that are built from one type of MBB, composed of cadmium and 4-imidazolecarboxylic acid. 36 Figure 3.12 4-IMC and cadmium ions are used to form a dia net from MN2(CO2)4 MBBs. 37

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vi Figure 3.13. 2,5-PDC and cadmium ions can be used to construct a kag -MOF from MN2O2 BUs resulting from MN2(CO2)4 MBBs 38 Figure 3.14. 4,5-IMDC and cadmium ions ha ve been used to create a metalorganic cube from a facMN3(CO2)3 MBB. 39 Figure 3.15. JB9545 is constructed from th ree types of MBBs yielding a net with unprecedented toplogy, which contains [62.74.84.94] tiles. 40 Figure 3.16. 4,5-IMDC and Cd are used to construct a (3,4)-net with unprecedented topology from two types of MBBs. The binodal network is built from four types of tiles. 42 Figure 3.17. Molecular building blocks, constructed from MNxOy ( x + y = 6) single-metal ions can facilitate the formation of various metalorganic materials. 43 Figure 4.1 A few zeolite frameworks are illustrated to display the porous nature of the naturally occurring aluminosilicate compounds. left : faujasite ( fau ) center : Linde Type A ( lta ) right : AlPO4-5 ( afi ) 46 Figure 4.2. ast, aco, asv, and lta are zeolitic nets clos ely related to basic 8-connected nets, and thus excep tionally interesting to metalorganic crystal chemistry. 48 Figure 4.3. In ltaZMOF, twelve MOCs are connected through a series of sodium ions (top left) to generate an -cage (tile shown in green) that can accommodate a sphere with diameter of ~32 and 6 MOCs assemble a -cage (tile shown in yellow) that can fit a sphere of ~8.5 in diameter. 51 Figure 4.4. An MN2(CO2)4 molecular building block can be exploited as an MN2O2 tetrahedral building unit. 55 Figure 4.5. Tiles of ana net. 56 Figure 4.6. 2,4-PDC and indium ions can be used to construct ZMOFs related to ana and sod nets 57 Figure 4.7. a) optical imag es of ion-exchange in anaZMOF with acridine orange. b) optical images of ion-exchange in sodZMOF. 58

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vii Figure 4.8. The nitrogen atoms (blue) of hexamethylenetetramine, situated in a tetrahedral arrangement, can coordinate to metal ions to act as a tetrahedral building unit, and, wh en connected through appropriate angles (as shown in green), can f acilitate the formation of zeolitelike metal-organic frameworks. 60 Figure 4.9. mep -ZMOF is constructed from [512] (yellow) and [51262] (green) cages. 64 Figure 4.10. mtn -ZMOF a) ball and stick representation (guests and acetate ions are omitted for clarity), b) view of net, and c) [512] (yellow) and [51264] (red) tiles. d) Ball and stick representation of sodZMOF, e) view of net and f) packing of [46.68] tiles. 65 Figure 4.11. sod -ZMOF, constructed from cadmium and HMTA. 66 Figure 5.1. Summary of structured from MNx(CO2)y Molecular Building Blocks. 68

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viii List of Abbreviations Acronym Full Name 1,3-DAP 1,3-Diaminopropane 2,4-PDC 2,4-Pyridinedicarboxylic acid 2,5-PDC 2,5-Pyridinedicarboxylic acid 4-EIC Ethyl 4-Imidazolecarboxylate 4-ICA 4-Imidazolecarboxylic acid 4,5-IMDC 4,5-Imidazoledicarboxylic acid BU Building Unit DEF N,N’-Diethylformamide DMA N,N’-Dimethylacetamide DMF N,.N’-Dimethylformamide En Ethylenediamine EtOH Ethanol FT-IR Fourier Transform Infrared HMTA Hexamethylenetetramine MBB Molecular Building Block MOC Metal-Organic Cube MOF Metal-Organic Framework MOM Metal-Organic Material

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ix MOP Metal-Organic Polyhedron n MRs n Member Rings Pip piperazine SBB Supermolecular Building Block SCD Single Crystal Diffraction TBU Tetrahedral Building Unit TGA Thermogravimetric Analysis UV-Vis Ultraviolet-visible XRPD X-Ray Powder Diffraction ZMOF Zeolite-like Me tal-Organic Framework ZIF Zeolitic Imidazolate Framework

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x Toward the Synthesis of Desi gned Metal-Organic Materials Jacilynn A. Brant ABSTRACT Metal-Organic Materials (MOMs) are an emerging class of crystalline solids that offer the potential for utilitarian design, as one of the greatest scientific challenges is to design functional materials with foreor dained properties and eventually synthesize custom designed compounds for projected appl ications. Polytopic or ganic ligands with accessible heteroatom donor groups coordina te to single-metal ions and/or metal clusters to generate networks of various dimensionality. Advancements in synthesis of solid-state materials have greatly impacted many areas of research, including, but not limited to, communication, computing, chemi cal manufacturing, a nd transportation. Design approaches based on building blocks provide a means to conquer the challenge of constructing premeditated solidstate materials. Si ngle-metal ion-based molecular building blocks, MNx(CO2)y+x, constructed from heterochelating ligands offer a new route to rigid and predictable MO Ms. Specific metal bonds are considered responsible for directing the geometry or topology of metal-orga nic assemblies; these bond geometries constitute the building units, MNxOy. When these building units are connected through appropriate angles, ne ts or polyhedra can be targeted and synthesized, such as metal-organi c cubes and Kagom lattices. MNx(CO2)y+x MBBs can result in MN2O2 building units with square pl anar or see-saw geometries, depending on the mode of chelation. Using a 6-coordinate metal and a heterochelating

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xi ligand with bridging functionality, TBUs can be targeted for the synthesis of valuable networks, such as Zeolite-like Me tal-Organic Frameworks (ZMOFs). Zeolitic nets, constructed from tetr ahedral nodes connected through ~145 angles, are valuable targets in MOMs, as they inherently contain cavities and/or channel systems and lack interpenetration. Other design approaches have been explored for the design of ZMOFs from TBUs, such as the use of hexamethylenetetramine (HMTA) as an organi c TBU. When this TBU coordinates to a 2-connected metal with appropr iate angles, zeolite-like ne ts rare to metal-organic crystal chemistry can be accessed. Additionally, MNx(CO2)y MBBs have been used to construct metal-organic polyhedra (MOPs), used as supermolecular building blocks (SBBs), that can be peripherally functionalized and ultimately extended into threedimensional ZMOFs. Rational synthesis, mainly based on building block approaches, advances bridging the gap between design and construction of solid-sta te materials. However, some challenges still arise for the establishm ent of reaction conditions for the formation of intended MBBs and thus targeted frameworks.

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1 Chapter 1: Introduction to Metal-Organic Materials Metal-Organic Materials (MOMs), a broa d class that encompasses solid-state coordination polymers, metal-organic framew orks (MOFs), and meta l-organic polyhedra (MOPs), generally consist of organic and me tal monomers linked through metal-organic bonds.1 Metal-organic interactions occur betw een metals and hetero-atoms, such as nitrogen, oxygen, sulfur and phosphorus. Poly topic ligands with a ccessible heteroatom donor groups coordinate to single -metal ions and/or metal clus ters to generate networks of various dimensionalities. Commonly, MOMs are synthesized as crystalline materials; a crystal consists of atoms a rranged in a pattern that re peats periodically in three dimensions.2 The crystallinity of MOMs implie s homogeneity throughout the solid phase, which expedites the pro cesses of purification, charact erization, property analysis and function determination. Crystalline mate rials aid understanding and development of design aspects for rational synthe sis of solid-state materials. 3 It has proven challenging to construct de signed rigid, thermally stable MOMs that retain structural integrity and contain large cavities and/or channels void of interpenetration. However, frameworks have been successfully created by designing molecular building blocks (MBBs) that direct th e formation of desired structures. Just as an architect must choose appropriate buildi ng material, (thatch, cl ay, or wood, etc.) for the project under construction, the MOM desi gner must deliberate appropriate metal and ligand combinations, and reaction conditions, to facilitate in situ formation and assembly of MBBs. It is essential that ligands contai n appropriate chemical attributes, since much

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2 of the resulting physical properties and the appr oaches to initially de signing the material depend on it. Throughout the evolution of MOM research a wide range of organic linkers have been investigated for exploitation in de sign and synthesis, in conjunction with the inquiry of various metals.4 1.1 Overview of History Early advancements in MOM developmen t resulted mainly from serendipitous and fortuitous discoveries of appropriate reaction conditions for the crystallization of coordination polymers, and a crystalline MOM wa s structurally charac terized as early as 1943.5 Combinatorial processes, colloquially termed “shake and bake”, yielded numerous interesting metal-organic ne ts and polyhedra, unveiling key knowledge associated with reactivity trends of hete ro-atom donating ligands a nd metal ions and/or clusters for exploitation in the emergence of a new class of crystalline materials. In the 1990’s an exceptional amount of research on coordination polymers focused on the development of nitrogen-donating organic compounds,6 such as pyridineand cyano-derivatives, for use as monodentate, polytopic ligands. As early as 1959, there were reports of using organi c ligands to form coordinati on polymers; specifically, a cyano-derivative was used as a linker between copper atom s in a coordination polymer with diamond-like topology.8 A variety of MOMs, contai ning nitrogen-donating ligands have been synthesized and studied,8-14 and ligands such as bipyridines,15-17 dicyanobenzenes,18-20 and cyanopyridines21 commonly facilitate the formation of diamondoid networks.22 An early example employs 4,4’-bipyridine (bpy) with an octahedral zinc metal ion to yield a square grid network. The 2-di mensional square grid layers pack ABAB and are cate nated by perpendicular layers of square grids that also

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3 pack ABAB. Through each of the four me mber rings (4MRs), a bpy ligand from a separate layer threads thr ough to interweave the layers. a) b) Figure 1.1 (a) Reaction of 4,4’-bipyridine with zinc ions yields 2-D square grids (red=oxygen, blue=nitrogen, gray=carbon, green=zinc) that interpenetrate, and (b) individual layers are shown in red, green, blue, and yellow.13 Early examples of MOMs constructed from Ndonor ligands were incl ined to collapse and lack structural integrity upon removal or exchange of guest molecules, rendering them unsuitable for many applications.23, 24 After the initial eruption in investigations of Ndonating ligands, carboxylates gained focus as linkers in design and synt hesis of MOMs, with the anticipation of forming more rigid frameworks.25-28 An interesting early example involves a coordination network, which contains 1,3,5-be nzenetricarboxylic acid and cobalt, is comprised of 2-dimensional layers that are held together by mutual -stacking of the pyridine guests with the benzene rings of BTC, which gives the framework physical properties that are closel y related to that of 3-dimensional frameworks.29 The compound,

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4 able to selectively bind aromatic guests, is stable up to 350 C, remains stable after removal of guests that can be selectivel y re-sorbed. Benzene, nitrobenzene, cyanobenzene, and chlorobenzene can all be adsorbed, while acetonitrile, nitromethane, and dichloroethane cannot be included within the framework. The selectivity of the framework is allegedly due to the -stacking of the aromatic guests with the benzene portion of the BTC ligand. Extensive research on incorporation of metal clusters, such as the copperpaddlewheel, has proven that adequate stre ngth and inflexibility is provided through carboxylate coordination with me tal ions for the design of MOMs. Crystallographic reports of the copper-paddlew heel occurred as early as 1823 by Brooke, research by Schabus, Groth, and Hull continued, and by 1953 J.N. van Niekerk and F.R.L. Schoening published the crystallographic data and stru cture of the mysteri ous cupric acetate molecule.30 Dimetal, tetracarboxylat e paddlewheel clus ters can be employed as square building blocks, containing othe r 6-coordinate metals, such as zinc, cadmium, and nickel, to construct MOMs.31-32 Other examples utilize the axial positions of the paddlewheel for coordination by bridging ligands to resu lt in networks with nodes of higher connectivities. Figure 1.2. illustrates the use of the paddlewheel clus ter as a 6-connected node, as 4,4’-bipyridine bri dges axial positions. Several other carboxylate based building uni ts have been used in the design and synthesis of MOMs, such as the octahedral “basic zinc acetate” cluster and the trigonal prismatic oxo-centered trimer.1 Many MOMs have utilized carboxylate-metal clusters as nodes and some possess unique applications.31-32, 34-35

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5 Figure 1.2. The use of the paddlewheel cluster as a 6-connect ed node is illustrated, as 4,4’-bipyridine bridges axial positions. 31 Numerous carboxylate contai ning coordination compounds have been produced and encompass high porosity and a conglomer ation of novel functionalities, including, but not limited to magnetism and gas storage. Networks encompassing paddlewheel and other chelated carboxylate building blocks ha ve proven to be thermally stable upon removal of guests.25,27 Exuberant studies have been based on a pplications of porous MOFs comprised of modifiable organic carboxylatebased linkers and metal clus ter nodes, which is evident from the unveiling of a class of isoreticular porous materials,25, 36-37 in which every compound has the same framework topology of CaB6. Sixteen different organic ligands were used as linkers to create the sixteen porous MOFs that constitute this class of compounds. Every compound in the series has a higher percent free volume than the most open zeolite, faujasite, and the family of compounds is ther mally stable up to temperatures between 300 and 400 C 25. The isoreticular family consists of frameworks composed of octahedral Zn-O-C clusters, [OZn4]6+, and various dito pic carboxylate linkers. The utilization of ditopic ligands of differing lengths yields structures containing various pore sizes with varyi ng gas storage capabilities.

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6 Figure 1.3. The basic zinc acetate cluster (left), composed of four tetrahedral metal ions coordinated by six carboxylates to form a 6-coordinate node, that is used to construct various IRMOFs with analogous topology to CaB6 (right).36 This work embraces many possibilities and exhibits numerous opportunities that MOF research can offer. This study provide s evidence that a spec ific network can be extended by consistently accessing a targeted building block. It has been proven that utilization of different organi c ligands can result in differe nt properties and thus unique functionalities. A plethora of diverse linkers have been utilized in the construction of various ionic and neutral MOFs. Anionic MOMs are ge nerated in the presence of cations, such as amines, to create charge balance,38-40 and several cationic MOFs have been constructed as well.41-43 In addition to the numerous io nic frameworks, there are also examples of neutral MOFs,44-45 and the synthesis thereof lacks the necessity for charge compensating ions. Neutral, anionic, a nd cationic ligands can be employed in the directed synthesis of materials with predispos ed ionic strengths, dependant mainly on the charge of building components a nd metal to ligand ratios.

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7 a) N N CN CN NCN N N N b) N N N N N N N N N N + + + + c) N O O O O N N H O O O O N N H O O Figure 1.4. a) Neutral, b) cationic, and c) anionic ligan ds can be used in the synthesis of MOFs with varying ionic strengths. Anionic MOMs are of extreme interest du e to the potential us e as metal-organic platforms that can be chemically tweaked via post-synthetic and/or ship-in-bottle ionexchange. In addition, the geometrics of or ganic and inorganic catio ns can be exploited to direct the formation of intended structures. 1.2 Fundamentals MOMs can be simplified and structurally e xplained in terms of nodes and spacers, as shown by Robson in the late 1980’s and early 1990’s, 9, 46-47 in which a node is generally any site in the netw ork with more than two connect ivities and a linker exhibits two connections. Metal-organic structures are classified as zero dimensional (discrete), one dimensional (chains), two di mensional (layers), and three

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8 dimensional. Discrete MOMs, not supporti ng or requiring the notion of continuity, generally exist as geometrically distinct pol ygons and polyhedra, such as a metal-organic squares and cubes. Metal-organic chains can be comprised of linear, zig-zag and ladderlike connectivities. Twoand three-dimensi onal networks are classified in terms of topology, an extension of geometry. Figure 1.5. 0-, 1-, 2-, 3-D (left to right) metal-organic materials depicted with nodes (green) and spacers (blue). Topological descriptors, such as coordi nation sequences and vertex symbols are used to identify and distinguish nets. The notion of coordination sequence (CS) was formally introduced by Brunner & Laves in 197148 in order to invest igate the topological identity of frameworks and of atomic positions within a framework. Each node, or vertex, in a framework has a CS, and, in an abst ract sense, the CS e xplains the growth of a network. For example, (Figure 1.6.) the co ordination sequence for the tetrahedral node in lta is 4, 9, 17, 28, 42, 60, 81, 105, 132, 162, which implies the first node (blue) is connected to 4 nodes (red), while those nodes are connected to 9 nodes (yellow), and the 9 nodes are connected to 17 nodes (green), etc. The coordination sequence {Nx} is a sequence N1, N2, N3… that shows the total number of atoms in the 1st, 2nd, 3rd …. coordination spheres.49

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9 Figure 1.6. The coordination sequence (4, 9, 17, 28, 42, 60, 81, 105, 132, 162) and vertex symbol (4.6.4.6.4.8) of the lta net are displayed. Vertex symbols indicate the size of rings that occupy a node. The symbols for opposite pairs of angles are group ed together and rings of the same size at a vertex are indicated by a subscript or s uperscript, depending on the not ation used. Additionally, the Schlfli symbol, named for the nineteenth cen tury mathematician Ludwig Schlfli, lists the numbers and sizes of circuits starting from any non-equivalent atom in the net. In the Schlfli symbol Aa.Bb.Cc, the length (number of nodes in a ring) of each shortest cycle is signified by A, B, C… and number of types of rings by a,b,c... The extended Schlfli symbol lists all shortest circuits for each angle for any non-equivalent atom. Other notations are also used to list such desc riptors, including Wells and O’Keeffe. For example, the vertex symbol of lta is 4.6.4.6.4.8 begins with 4.6 as smallest circuit is a 4MR which is opposite to a 6MR.50 In crystal chemistry, the formation of regular nets is common, and sometimes unavoidable. The regularity of a net is categorized in terms of transitivity, pqrs which specifies the number of kinds of vertices ( p ), edges ( q ), essential rings ( r ), and tiles ( s ). For example, the transitivity of the dia net is 1111, therefore it is a regular net and thus

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10 highly favorable for formation in crystal ch emistry. Essentially, transitivities, although composed of four digits, can be viewed as a single number; more regular nets have lower numerical transitivities and are generally more easily accessed by the metal-organic material designer. The lta net has the transitivity 1343. Th e three edges can be viewed as (1) the edge between squares and he xagons, (2) the edge between squares and octagons, and (3) the edge between hexagons and octagons. There are four types of faces, which are determined by congruency a nd symmetry. The net has three types of tiles, [46], [46.68], and [412.68.86]. Figure 1.7. The lta net contains three types of tiles [46] (blue), [46.68] (yellow), and [412.68.86] (red). The lta net and others with similar attribut es are targeted networks in MOMs for applications relying on porosity, as the tiles can be translated into metal-organic cages. The tiles pack in a manner to expose intersecting channels. Such porous structures can be classified according to spatial dimensions of the pores or cavities, which include zerodimensional (dots), one-dimensional (channels ), two-dimensional (layers), and threedimensional pore systems (intersecting channels).4 3-D pore systems are extremely useful due to the induced mobility of guests or solvent molecules. Various layered MOFs, containing 2-D pore systems, have been repo rted, however most of them are unable to

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11 host several guests. Guest molecules residing in 1-D pore systems are free to move in one direction, while guests present in 0-D por e systems are isolated from other cavities and are unable to pass to other cavities. Th e possible applications of a specific porous material are generally dependant on the type of pore system that is embedded within the framework. Research involving porous mate rials has been developing for many years. Essentially, a permanently porous framewor k remains robust, with out reversible or irreversible collapse, during guest loss, which results in a stable framework that contains a vacuum in the channels of the framework.35 1.3 Challenges The most significant challenge associated with MOMs is to combine knowledge of chemical reactivity, cr ystallization techniques, and basic nets with aspects of utilitarian function to design and synthesize materials for specific applica tions. Although some frameworks containing nitrogen -donating ligands are robust, t hus far, the employment of carboxylate-containing ligands a nd metal-clusters have been more widely employed in creating irreversibly porous open frameworks.26, 65 N-donating ligands have been proven to act as effective linkers in MOFs, however, the typica l flexibility of the M-N bond impedes topological design39 and monodentate N-based ligands do not commonly result in permanently porous nets.66,67 1.4 Advancements/Developments Carboxylate-based ligands continue to be used in the synt hesis of MOMs with some of the largest cavities exhibited in solid-state materials. For example, an exceptional material, namely MIL-101, is cons tructed from chromium and terephthalate with cages about 34 in diameter and an unprecedented free volume of about 702,000

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12 3.52 A mesoporous MOF, made with triazine -1,3,5-tribenzoic acid and terbium, has been reported with two type s of cages, one with 39 and the other 47 in diameter.53 Advances in design and rational synthesi s of targeted materials, with large cavities/channels void of interpenetrati on, continue to benefit applications,54 such as catalysis,55-57 gas storage,58-59 and sensing60. Recently, it has been demonstrated that imidazole-based linkers that exhibit monodentate coordination can successfully be used for the construction of Zeolitic Imidazolate Frameworks (ZIFs). ZIFs are c onstructed by the coordi nation of imidazolate and imidazolate-type linkers to tetrahedral si ngle metal ions, such as Co and Zn. These examples prove that extensive explorati on of reaction conditions can allow access to zeolitelike topologies, and thus avoidances of di amond-like networks. ZIFs have surface areas up to 1,970m2/g, thermal stability and exceptional chemical stabilities. Additionally, these porous frameworks are su itable for gas storage and can selectively capture CO2 from CO/CO2 mixtures.51

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13 Chapter 2: Introduction to Rational Synthesis of Metal-Organic Materials 2.1 Overview Serendipitous discoveries have been very fruitful and will continue to yield valuable solid-state materials and insights to design. Although much progress in research pertaining to solid-state materials has been made,3,35 the same basic synthetic approaches have been utilized for the majority of the twentieth century.61 Recently, synthesis of solid-state compounds progressively resembles ra tional approaches used in other fields of chemistry, such as organic chemistry, due to the use of building blocks. Unlike organic chemistry, which involves the union of building blocks in a stepwise fashion, or by one functional group at a time, synthesis of soli d-state materials is feasibly viewed as concerted processes. The f act that all bond-making and b ond-breaking is considered simultaneous explicates the great challenge s associated with positioning chemically active groups in a manner to facilitate inte nded interactions. Perhap s, one day synthesis of solid-state materials will entirely entail pr e-designed systematic approaches that will allow synthetic researchers to design made-toorder materials. Currently, it is often possible to predict likely structures th at result from certain building blocks,28 but the challenge remains to actually synthesize desi gned materials, while avoiding non-target nets that may have more favorable formation. Approaches based on the use of molecular building blocks (MBBs) offer great potential.

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14 2.2 Fundamentals As mentioned earlier, networks with lo wer numerical transitivities are easier targets in crystal chemistry. Transitivity classifications aid the MOM designer to envision and anticipate the formation of specific nets fr om regular vertex figures. While some of these nets are exciting for some a pplications, other, less regular nets with analogous coordination figures ar e often targeted. By understanding the types of nets that are likely to form, one can targ et avoiding certain structures in order to obtain those with higher transitivities. Z Coordination Figure Name Transitivity 3 triangle srs 1111 4 square nbo 1111 4 tetrahedron dia 1111 6 octahedron pcu 1111 8 cube bcu 1111 12 cuboctahedron fcu 1112 4 rectangle lvt 1121 4 tetrahedron sod 1121 4 tetrahedon lcs 1121 4 tetrahedron lcv 1121 4 tetrahedron qtz 1121 6 hexagon hxg 1121 6 metaprism lcy 1121 6 octahedron crs 1122 6 octahedron bcs 1122 6 trigonal prism acs 1122 8 tetragonal prism reo 1122 8 bisdisphenoid thp 1122 4 rectangle rhr 1132 4 tetrahdedron ana 1132 Figure 2.1. Regular, quasi-regular, and semi-regular nets, cl assified by transitivity, are prime targets for the synthesis of pre-designed networks.61-62 Regular nets are defined to have symm etry that requires a regular polygon or polyhedron coordination figure, or viewed in terms of natural ti ling, in which the

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15 Figure 2.2. Edge transitive, binodal nets represent a class of lucrative nets to target.63-64 transitivity is equal to 1111.63 Such nets, as srs and dia, have been referred to as default nets for 3-D nets, for triangular and tetrahedra l nodes, respectively. These types of nets Z Coordination Figure NameTrans. 4,6 tetrahedron, octahedron iac 2123 4,24 octahedron, truncated octahedron twf 2123 6,8 octahedron, cube ocu 2123 6,12 hexagon, truncated tetrahedron mgc 2123 3,24 triangle, rhombicuboctahedr on rht 2123 4,4 quadrangle, quadrangle ssc 2131 4,4 rectangle, tetrahedron pts 2132 4,4 rectangle, tetrahedron pth 2132 4,6 rectangle, trigonal prism stp 2133 4,8 rectangle, tetragonal prism scu 2133 4,12 rectangle, hexagonal prism shp 2133 6,12 trigonal prism, hexagonal prism alb 2134 4,4 quadrangle, quadrangle ssa 2143 4,4 quadrangle, quadrangle ssb 2143 4,8 quadrangle, cube csq 2155 Z Coordination Figure Name Trans. 4,8 tetrahedron, cube flu 2111 3,6 triangle, octahedron pyr 2112 4,12 square, cuboctahedron ftw 2112 4,8 quadrangle, cube sqc 2121 3,4 triangle, square pto 2122 3,4 triangle, tetrahedron bor 2122 3,4 triangle, tetrahedron ctn 2122 3,6 triangle, octahedron spn 2122 4,6 square, octahedron soc 2122 4,6 square, hexagon she 2122 4,6 tetrahedron, octahedron toc 2122 4,6 tetrahedron, octahedron gar 2122 4.6 tetrahedron, octahedron ibd 2122 4,12 tetrahedron, ocoshedron ith 2122 6,6 octahedron, trigonal prism nia 2122 3,4 triangle, rectangle tbo 2123 3,8 triangle, tetragonal prism the 2123 3,12 triangle, truncated tetrahedron ttt 2123

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16 crystallize frequently, especially from bu ilding blocks that lack rigidity, and are commonly unavoidable. A quasi-regular net, fcu, is vertex-, edge-, and face-transitive, 1112 and semi-regular nets have 11 rs transitivities.62 For example, semi-regular net sod has 1121 transitivity and is described as vertex, edge, and tile transitive. Vertex transitive nets are referred to as uninodal and edge transitive as isotoxal and represent easily accessible networks. In addition to regular, qua si-regular, and semi-regular nets, binodal edge transitive nets are feasible targ ets for rationally constructed materials. Recent MOM design includes expansion of known networks sel ected as targets, which are often prevalent in nature. An approach, coined “topdown design, bottom up synthesis,”39 entails the following process. Fi rst, the target network should be intellectively anatomized, or deconstructed into essential building blocks of specific geometry, directionality, and connectivity that are required for th e construction of the network. Organic ligands and metals, which can be exploited to construct appropriate MBBs, are deliberated to essentially construct the targeted network.34 Geometrical information of the intended coordination figures are recreated with a linker or combination of linkers, single-metal ions, a nd/or metal clusters. Building blocks should be rigid in order for the geometric informati on to be retained during network assembly. Linkers that remain rigid allow more control of the binding angle be tween the extensions of the polytopic linkers. When designing por ous materials, nonflexible building blocks are beneficial for the creation of rigid fram eworks that will remain permanently porous upon evacuation of guests. When single metal nodes are util ized, ligands should be able to lock the metal into position, causing rigidity of the entire framework.

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17 As an example of expansion, in which th e distance between the vertices of the target framework is increased, the zeolite net rho is targeted. It can be realized that rho consists of -cages, or truncated cuboctahedra ([412.68.86]). The cages connect through a double 8 member ring (d8MR), re sulting in a body centered cubi c arrangement, to yield a 3-dimensional channel system of 8MRs. The cages are composed of twelve 4MRs, eight 6MRs and six 8MRs. The framework can be furt her dissected to reveal that each of these rings, and ultimately the -cage, is essentially built from 4-coordinate tetr ahedral nodes. Figure 2.3. The rho net can be intellectively dismantled to an essential tetrahedral building units linked through an approximate 145 angle and consequently rebuilt and expanded using metal-organic molecular building blocks (MBBs).65 Assembly of tetrahedral coordination figures is likely to result in regular nets, such as dia, sod, lcs, lcv, etc., therefore, more information must be invested in the MBBs to avoid such regular nets. The 48 tetrah edral nodes are connected through an average angle of 145 Next, one must determine which metals and ligands can be exploited to construct a MBB that is rigid, tetrahedral and facilitates 145 angle connections. This particular case demonstrates that a metal with 8-coordination sites can be combined with a ditopic heterochelating ligand to form 4-c oordinate tetrahedral bui lding units (TBUs). 4,5-imidazoledicarboxlate (4,5-IMDC) has the capability to act as a ditopic N-, Oheterochelating ligand and the metal-nitrogen bonds can be used to direct the topology,

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18 while carboxylate oxygen atoms can lock the metal nodes into position. 4,5-IMDC contains nitrogen atoms oriented to fac ilitate connection of metal nodes though ~145 angles. Figure 2.4. 4,5-IMDC and In3+ are used to make a TBU for the assembly of anionic rhoZMOF. Under experimentally ascertained sol vothermal conditions, the indium-based MBBs assemble in situ and a zeolitelike MOF (ZMOF) with rho topology, namely rhoZMOF, is constructed. Expansion is accomp lished, and the cavities can accommodate a sphere with approximate diameter of 18.2 . The unit cell is approximately 8 times larger than the aluminosilicate zeolite rho 65 2.3 Challenges A key to targeting materials is consideri ng the plethora of po ssible outcomes and narrowing the list by introduci ng constrictive components. Challenges remain in the selection of suitable MBBs for coordination figures of targeted nets, and ultimately metal and ligand combinations. As the qualifications for metals and ligands are realized for construction of MBBs for targeted materials, reaction conditions must be established for the formation and assembly of the MBBs. U nder relatively mild conditions, the polytopic linkers and the appropriate metal nodes must be linked, retaining rigidity and geometric information throughout the synthesis, to fo rm MOMs having the desired topology. Both

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19 the linkers and nodes must have attributes that accommodate the intended coordination figures, and commonly more intelligence must be incorporated to avoid simple nets. It is important that the MBB is rigid and geometri cally inductive, as structure ductility may defy the intention of avoiding certain hi gh-symmetry, simple nets. As the MBB of interest is realized, reaction conditions fo r assembly must be discovered. As many interesting nets commonly result from the same coordination fi gure, a MBB should be reproducible in the presence of slight vari ations, such as ligand length for expansion, structure directing agents (SDAs) for vers atility, and functionaliz ation for utility. Determination of adequate reaction conditions is the remaining challenge to catenate design and synthesis of the target materials. 2.4 Advancements/Developments A single-metal ion-based MBB approach em ploys ligands that contain a nitrogen atom in the -position relative to a carboxylate group, which facilita te the formation of 5membered rings of chelation, with metal i ons capable of high coordination numbers to form rigid and robust frameworks.68 Generally, chelates of higher denticity will result in building blocks with more predictable or ientations than monodentate ligands. Potentially, metal-nitrogen bonds will direct the topology of the resultant network, while oxygen atoms can be used to complete the c oordination sphere of single metal vertices, locking the metals into position through chelation. This approach combines the directionality induced by N-donating ligands an d the rigidity of fr ameworks built from metal-clusters. Incorporating rigid build ing blocks into MOM design will enhance structure prediction. Utilizing heterochela ting ligands with geom etrically stringent

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20 Figure 2.5. Rigid MN3(CO2)3 MBB, from a heterochelating ligand, (center) has a rigid geometry, while the N-based building block (left) and paddle-wheel building block (right) show the potential for bond rotations. bridging capabilities allows access to ta rgeted, and sometime rare and unprecedented, framework topologies in meta l-organic crystal chemistry. In certain cases, general conditions for the formation of specific MBBs have been established. Sometimes, these established conditions can be us ed for the synthesis of isoret icular networks of varied metals and/or ligands. Additionally, some results imply that certain conditions are successful for specific ligand families and ce rtain types of metals. For established methods, such as the formation of paddlewh eel building blocks from metal ions and carboxylate-based ligands, simple conditions containing appropriate metal-to-ligand ratios and N,N’-dimethylformamide solvent sy stems can be applied to various nodes and spacers. Trends can be analyzed from results of combinatorial chemistry and employed in the directed synthesis of materials.

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21 Chapter 3: Single-Metal Ion-based Mol ecular Building Block Approaches for the Advancement of Metal-Organic Material Design 3.1 MNx(CO2)y Molecular Building Blocks Co nstructed from Nitrogenand Carboxylate-Based Heterochelating Ligands The directionality of the nitrogen-based ligands and the rigi dity of carboxylatebased MOFs are combined by incorporating he terochelating capabilities into judiciously designed ligands. The strategy to design and synthesize metal-organic assemblies consists of the formation of rigid and dire ctional single-metal-ion based MBBs, namely Figure 3.1. (Left) Heterochelating ligands with bridging functionality: (a) 4-imidazolecarboxylic acid, (b) 4,5-imidazoledicarboxylic acid, (c) 4-imidazolethanoate, (d) 2,4-pyridinedicarboxylic acid, (e) 2,5pyridinedicarboxylic acid, and (f) 4,6-pyrimidinedicarboxylic acid. (Right) Isomers of MNxOy single metal ions. MNx(CO2)x+ y that contain x N-, Ochelating moieties, and y bridging carboxylates. Such ligands, which possess both the chelating a nd bridging functionalit y, are shown in Figure 3.1.

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22 Herein, 4-connected nodes, derived fr om MBBs based on 6-coordinate singlemetal ions, MNxOy ( x + y = 6), will be considered for the construction of robust metalorganic assemblies. Specifica lly, MBBs are targeted from cisand transisomers of MN2O4 and MN4O2 and facand mer -isomers of MN3O3 using directional ligands, such as 2,5-PDC, 2,4-PDC, 4,5-IMDC, Et 4-IMCand 4-IMC. 3.1.1 MN4O2 Single Metal Ions in Molecular Building Blocks MN4O2 single-metal ions can be formed by the coordination of various types of heterochelating ligands, in cluding those with two ni trogen donor atoms and one carboxylate group, such as 4imidazolecarboxylate. MN4(CO2)2 MBBs yield building units (BUs), which direct th e topology, with seesaw or square planar geometries. In contrast with the geometries of MN2O2 BUs, derived from MN2(CO2)4 MBBs, which rely on chelation and coordination modes, the geometry of the resultant MN4 BUs from MN4(CO2)2 is dependant only on the mode of coordination. Obviously, since the nitrogen atoms are responsible for directi ng network topologies, th e configuration of coordination directs fr amework formation. Figure 3.2. MN4O2 single metal ions can be used to access seesawand square planar-like building units.

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23 3.1.2. MN2O4 Building Units derived from MN2(CO2)4 Molecular Building Blocks Two types of configurational isomers, cisand trans, are accessible in the octahedral hetero-coordina ted single metal ion MN2O4, resulting in various types of MBBs in which topological directors have s quare planar-like or see-saw-like geometries. The transMN2(CO2)4 MBB can yield a square-planar-like building unit (BU), which results from transchelation66 and a see-saw-like BU is a product of cis -chelation. Three possible types of MBBs can be constructed from cistype coordination, depending on the sites of chelation, from which different SBUs can be derived. Configurational cis -isomers bear two types of see-saw-like SBUs as we ll as a square planar-like SBU (Fig. 3.3). Figure 3.3. Heterochelating ligands can coordinate to single-metal ions to result in MN2(CO2)4 molecular building blocks that act as 4-connected square-planarand see-sawlike building units. We have previously reported67 the congregation of single-metal-ion-based MBBs, with the general formula InN2(CO2)4, resulting in the assembly of two supramolecular

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24 isomers, a Kagom lattice and a M6L12 octahedron from the heterochelating ligand 2,5PDC. The metal-organic Kagom lattice c onsists of 4-connected MBBs, exhibiting cischelation, that act as square -planar BUs. The discrete M6L12 octahedron is constructed from an InN2(CO2)4 MBB that constitutes a see-saw-like BU. In both examples, a multifunctional heterochelating and bridging ligand, 2,5-pyridinedicarboxylate, connects the nodes through ~120 angles to configure the rati onally expected networks. The rigid, geometry inducing ligand, 2,5-pyridinedicarboxyl ate, links the single-metal ions to generate a discre te MOF of the M6L12 octahedron. Yet another MOF, involving the multifunctional 2,5-pyridinedicarboxylate ligand, includes a configurational cis -isomer of the single-metal-ion and thus the MNx(CO2)y MBB, namely FeN2(CO2)4. The FeN2(CO2)4 represents the third type of MBB, in which cischelation affords a see-saw-like SBU. In this type of see-saw, two diffe rent types of atoms are present in the lever and the fulcrum, as opposed to the see-saw-like SBUs found in th e isoreticular octahedr on structures that have one type of atom in the lever (oxygen) an d the other type (nitr ogen) in the fulcrum. The see-saw-like MBBs assemble, through th e multifunctional linkers, to yield a MOF related to the cubic diamond net. This wo rk demonstrates that by accessing different MBBs, and thus different BUs, with a consistent ligand ( 2,5-PDC), various networks can be formed.68

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25 Figure 3.4. MN2(CO2)4 MBBs are used to construct a metal organic Kagom lattice, an octahedron, and diamond-like net.68 3.1.3 MN3O3 Building Units derived from MN3(CO2)3 Molecular Building Blocks The MN3O3 octahedral single-metal ion can exist as two possible geometric isomers, the facisomer and the merisomer (Figure 3.5). As the nitrogen atoms are considered to direct the topology of resultant structures, two types of BUs are accessible from this type of coordination, namely merMN3 from mer -MN3(CO2)3 and facMN3 from fac -MN3(CO2)3 Examples of the mer -MN3(CO2)3 MBB exist,69-71 but to our knowledge, these types of MBBs involving 5member rings of chelation are rarely reported as part of extended coordination polymers. However, extended structures involving analogous non-chelating merMN3O3 building blocks have been synthesized.72 Previously, we have re ported the occurrence of facNiN3(CO2)3, in which the facial metal-nitrogen bonds topologically direct the formation of a cube (Figure 3.6).73 It is

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26 Figure 3.5. MN3(CO2)3 molecular building blocks can be viewed an fac(top) or merMN3O3 (bottom) building units. apparent that the majority of the crystal st ructures containing tris -chelated octahedral nickel, NiN3(CO2)3, deposited on the Cambridge Structur al Database (CSD) have facial geometry. The metal-nitrogen bonds of the MBB geometrically constitu te the corner of a cube and NiN3(CO2)3 has been employed in edge-directed assembly of an anionic metalorganic cube (MOC-1), which has Ni-Ni-Ni angles within the range of 88.28(1) to 91.85(1) Figure 3.6. A metal-organic cube is constructed from a facNiN3(CO2)3 MBB.73

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27 3.2 Experimental All chemicals were used as received fr om Fisher Scientific, Sigma-Aldrich, and TCI America chemical companies. Fourier transform infrared (FT-IR) spectra were measured using an Avatar 320 FT-IR system. Absorptions are described as follows: very strong (vs), strong (s), medium (m), weak (w ), and broad (br). X-ray powder diffraction (XRPD) data were recorded on a Rigaku RU15 diffractometer at 30kV, 15mA for CuK ( = 1.5418 ), with a scan speed of 1 /min and a step size of 0.05 in 2 Calculated XRPD patterns were produced using Powd erCell 2.4 software. Single-crystal X-ray diffraction (SCD) data were collected on a Bruker SMART-APEX CCD diffractometer using MoK radiation ( = 0.71073 ) operated at 2000 W power (50 kV, 40 mA). The frames were integrated with SAINT software package74 with a narrow frame algorithm. The structure was solved using direct methods and refined by full-matrix least-squares on | F |2. All crystallographic calculations were conducted with the SHELXTL 5.1 program package,75 and performed by Dr. Victor Krav tsov, Dr. Lukasz Wojtas, Dr. Derek Beauchamp, Dr. Rosa Walsh or Gregory J. Mc Manus in the Department of Chemistry at the University of South Florida. Crystall ographic tables are included for each compound in Appendix I Olex76 and Topos77 software was used to determin e topological representations of the obtained MOMs, and the resulting terms comp ared to those in the literature and the RCSR database.50 Total solvent-accessible volumes were determined using PLATON78 software by summing voxels more than 1.2 away from the framework. Tiling was evaluated using 3dt software.79

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28 Synthesis of {[Cd(4-ICA)2]}n, ME086 Cd(NO3)2 4H2O (9mg, 0.0435mmol) and 1 H imidazole-4-carboxylic acid (4-ICA) (7.3mg, 0.0653mmol) were added to a solution of DMF (1mL), water (0.5mL), imidazole (1.46M in DMF, 0.1mL) and nitric acid (2.85M in DMF, 0.225mL) in a 20mL scintillation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, yielding colorless faceted polyhedral crystals. Experimental XR PD: 14.0, 18.1, 19, 23.5, 26.2. Calculated XPRD: 13.92, 18.18, 19.08, 23.1, 26.4, 28.06, 29.52, 31.8, 32.4, 35.0, 36.0, 37.06, 39.6 Synthesis of {[Cd(4,5-IMDC)(en)]}n, ME089 Cadmium (II) acetate dihydrate(0.0435mmol, 11.6 mg) was added to 4,5-IMDC (0.087mmol, 13.6mg) in the presence of DMF (1mL), and nitric acid (350 L of 2.96 M in DMF). The reaction was heated to 65C at 1.5C/min. The reaction re mained at 65C for 12h and was then cooled to room temperature at a rate of 1C/min. Experimental XRPD: 9.7, 11.5, 15.5, 18.0, 19.4, 25.1; Calculated XRPD: 7.86, 8.82, 9.66, 10.63, 11.38, 11.96, 15.4, 15.7, 17.8, 19.4, 20.2, 20.93, 22.4, 25.3, 26.6, 27.35, 30.8, 34.1. Synthesis of [In6(2,5-PDC)12], ME694. In(OAc)3 H2O (0.0435mmol) and 2,5pyridinedicarboxylic acid (0.087mmol) were added to a solution of DMA (1mL) and 0.1mL 0.058 M piperazine/DMF in a 20mL scin tillation vial. The r eaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min Colorless block-like crystals resulted IR: 3156.7 (br), 1667 (m), 1566 (s ), 1482.2 (w), 1395(s), 1350.9 (s), 1266 (w), 1104 (w), 1018.8 (m), 942.4 (w), 834 (s), 756.9 (s), 694.7 (w), 648.6 (w). Experimental

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29 XRPD: 5.17, 6.16, 6.41, 7.029, 8.14, 8.89, 9.75, 10.62, 11.61, 11.98. Calculated XRPD: 5.1, 6.02, 6.45, 6.8, 7.0, 7.45, 7.95, 8.85, 9.75, 9.9, 10.61, 11.04, 11.2, 11.64, 12.02, 13.1, 13.3, 13.66, 13.96, 14.25, 15.77, 15.9, 16.33, 16.9, 17.5, 18.1, 20.3, 21.83. Synthesis of {[Cd(4-ICA)2]}n, ME207 Cd(NO3)2 4H2O (9mg, 0.0435mmol) and 1 H imidazole-4-carboxylic acid (4-ICA) (7.3mg, 0.0653mmol) were added to a solution of DMF (1mL), water (0.5mL), imidazole (1.46M in DMF, 0.1mL) and nitric acid (2.85M in DMF, 0.225mL) in a 20mL scintillation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, yielding colorless faceted polyhedral crystals. Experimental XRPD: 13.2, 14.304, 19.71. Calculated XPRD: 7.16, 9.27, 10.19, 12.07, 13.08, 14.35, 14.96, 16.62, 16.6, 20.45, 21.25, 21.97, 22.56, 23.13, 23.69, 24.44, 25.22, 25.66, 30.19, 30.75, 36.35 Synthesis of {[Cd(4-IMC)(H2O)]}n, ME096. Cd(NO3)2 4H2O (7.5mg, 0.0217mmol) and 4-ICA (4.9mg, 0.0435mmol) were added to a solution of DMF (0.5mL), water (0.125mL), 4,4’-trimethylenedip iperidine (0.95M in DMF, 0.05mL) and nitric acid (2.85M in DMF, 0.1mL) in a 20mL scintillation vi al. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C. Colorless block-like crystals resulted Experimental XRPD: 7.7, 15.4, 21.9, 23.6, 26. 6; Calculated XRPD: 7.7, 15.5, 22, 23.5, 26.7 Synthesis of [Cd8(4,5-IMDC)12], ME299 Cd(OAc)2 2H2O (232mg, 0.87mmol) and 2,5-PDC) (340mg, 2.18mmol) were added to a solution of N,N’-diethylformamide (DEF)

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30 (20mL), ethanol (EtOH) (10mL) and HMTA (1.42M in H2O, 2mL) in a 20mL scintillation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, heated to 105 C and cooled to r.t. yieldi ng colorless octahedral-like crystals. Experimental XRPD : 12.1, 15.9, 17.5, 19.9, 20.6, 26.2, 28.1, 29.8, 32.9, 35.2; Calculated XRPD: 10.2, 12.1, 12.7, 14.6, 15.9, 16.3, 17.9, 19, 20.7, 21.6, 22, 23.4, 24, 24.4, 25.5, 26.2, 27.5, 28.3, 33, 36.3, 37 Synthesis of [Cd(4,5-IMDC)(en)]n, ME511 Cd(OAc)2 2H2O (11.6mg, 0.0435mmol) and ethyl 4,5-IMDC (13.6mg, 0.087mmol) were added to a solution of DMA (0.75mL), En (2.96M in DMF, 0.325mL) and EtOH (0.5mL ) in a 20mL scintillation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, yielding colorless octahedron-like crys tals. Experimental XRPD: 13.5, 14.0, 16.3, 18.9, 20.0, 26.0. Calculated XRPD: 11.95, 13.3, 14.1, 15.6, 16.14, 18.7, 19.4, 19.96, 23.3, 25.8, 28.3, 30.2, 27.05. Synthesis of [Cd(4-EIC)2]n, ME184 Cd(NO3)2 4H2O (13mg, 0.0435mmol) and ethyl 1 H -imidazole-4-carboxylate (4-EIC) (12mg, 0.0 87mmol) were added to a solution of DMF (2mL), and EtOH (1mL) in a 20mL scintil lation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, yielding colorless faceted polyhedral-like crystals. IR: 1727(s), 1685 (w), 1604 (w), 1505 (s), 1392 (m), 1266 (w), 1193(s), 11.76 (s), 1138 (s), 1024 (m), 966 (s), 896 (s), 852 (s), 677 (s). Experimental XRPD: 10.663, 15.184, 21.436, 28.588; Calculated XRPD: 10.67, 13.14, 15.05, 15.18, 16.9, 18.55, 21.44, 22.79, 23.92, 25.15, 25.3, 27.39, 28.54, 30.37, 30.95, 31.5, 37.6.

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31 Synthesis of Formula, [Cd3(4,5-IMDC)4DMF]n, JB9545. Cd(OAc)2 2H2O (11.6mg, 0.0435mmol) and 4,5-IMDC (13.6mg, 0.087mmol) were added to a solution of DMA (0.75 mL), and EtOH (0.5mL) and en (0.325mL 2.96M in DMF) in a 20mL scintillation vial. The reaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, heated to 105C for 23h, cooled to r.t ., heated to 105C for 23h and cooled to r.t. yielding colorless hexagonal plat e-like crystals. XRPD: 6.26, 7.18, 7.83, 8.51, 9.89, 10.43, 13.11, 15.14, 18.56; Calculated XRPD: 6.27, 7.19, 8.51, 9.7, 10.25, 10.4, 11.25, 13.2, 18.88, 24.2 Synthesis of [Cd6(4,5-IMDC)10]n, ME688. Cd(OAc)2 2H2O (11.6mg, 0.0435mmol) and 4,5-IMDC (13.6mg, 0.087mmol) were adde d to a solution of DMA (0.75 mL), DEF (1.25mL) and 1,3-DAP (0.1mL). The r eaction was heated at a rate of 1.5 C/min to 85 C for 12h, cooled to r.t. at 1 C/min, yielded colorless faceted polyhedral crystals. Experimental XRPD: 3.7, 4.7, 6.3, 8.4, 9.1, 11.7, 14.7; Calculated XRPD: 3.87, 4.67, 6.2, 8.35, 9.04, 11.15, 11.65, 14.63, 14.92, 18.13 3.3 Results & Discussion 3.3.1 MOMs resulting from MN4O2 Single-metal ion-based Building Blocks A reaction between a 1:2 ratio of cadmium nitrate and 4,5-IMDC in the presence of ethylenediamine yielded a metal-or ganic zig-zag chain, {[Cd(4,5-IMDC)(en)]}n (ME089) The ditopic ligand chelates to the cadmium in a bidentate fashion. However, two of the binding sites on the metal are o ccupied by ethylenediamine, which acts as a

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32 terminal ligand. Due to the unintended c oordination of ethylenediamine, 2-connected building units, CdN2, result from the assembly of CdN4(CO2)2 MBBs. Figure 3.7. Two types of 2-connected MBBs comb ine to form zig-zag chains in ME089. Another reaction condition containing 4,5 -IMDC, cadmium, and ethylenediamine yielded interpenetrated 3-D nets, ME511, {[Cd(4,5-IMDC)(en)]}n. The single-metal ion is coordinated by two monodentate ethylened iamine bridges and two heterchelating 4,5IMDC ligands in a transcoordination and transchelation mode, to result in a neutral MOM. Each net is vertex transitive, with a Schlafi symbol of 4(2) .8(4) and coordination sequence: 4, 10, 24, 44, 68, 98, 132, 172, 218, 266, which are id entical to the chiral uoc net. The uoc net is isohedral, and the tile consists of 4and 8MRs. The double interpenetration obstructs the 4and 8MRs resulting in a densely packed framework. Once again, the unintentional coordination of ethylenediamine impedes structure

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33 prediction. However, this serendipity allowed access to a framework previously uncommon in MOMs. Figure 3.8. Doubly Interpenetrated uoc nets are constructed from a MN4O2 single-metal ion-based MBB, consisting of cadmium, 4,5-imidazo lecarboxylate, and ethylenediamine. Ethyl 4-imidazolecarboxylate (4-EIC) was reacted with cadmium in a solution of DEF and EtOH targeting an CdN4(CO2)2 MBB, however an CdN4 MBB resulted. The single-cadmium ion is coordinated by the nitrogen atom neighboring the carboxylate (Cd..N 2.25) in 4-EIC, while the 4-position nitrogen atom (Cd..N 2.19) further extends the neutral structure. When simp lified into spacers and 4-connected nodes,

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34 Figure 3.9. ME184, of dia topology, is constructed from a tetrahedral CdN4 building block. ME184 has dia topology, as exhibited by the 6(2).6(2) .6(2).6(2).6(2).6(2) vertex symbol and 4, 12, 24, 42, 64, 92, 124, 162, 204, 252, 981 coor dination sequence. Recent studies have proven that the MOF is stable in wa ter, common organic so lvents, and sodium hydroxide solutions at elevated and room temperatures. 3.3.2 MOMs from MN2O4 Single-Metal Ion-based MBBs Reaction of 2,5-PDC and indium, in a 1:2 ratio, yielded a disc rete metal-organic octahedron, [In6(2,5-PDC)12], ME694. The ditopic 2,5-PDC lig and heterochelates to the indium ion, while the 5-position ca rboxylate bridges resulting InN2(CO2)4 MBBs, through monodentate coordination. As th e nitrogen atoms, participa ting in heterochelation, and carboxylate oxygen atoms, coordinated in a mo nodentate fashion, direct the topology, the BU can be described as a distorted seesaw, in which the nitrogen atoms that constitute the fulcrum of the seesaw are have an approximate N-In-N bond angle of 154.5 When the

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35 distorted BU is combined with a ligand of ~120 angle, a MOP with octahedral geometry results. Figure 3.10 [In6(2,5-PDC)12] consists of 4-connected MBBs with the formula MN2(CO2)4. Overall, six indium atoms and twelve liga nd molecules are present in each of the discrete structures, encompassing an inner cavity with an approximate volume of 2613, and a charge of -6 per octa hedron. Each anionic polyhed ron is accommodated by three piperazine guests, which bridge the stru cture, through hydrogen bonding, into three dimensions to result in small channels. 4-Imidazolecarboxylic acid (4-ICA) is used as a ditopic asymmetric ligand with one site of possible hetero-chelation and an additional nitrogen donor available for coordination to a metal ion. The angle between coordination sites in this ligand is 145 and used to target MN4(CO2)2 MBBs.

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36 A reaction of cadmium and 4-ICA, under solvothermal conditions, results in the generation of a 1-D zig-zag polymer, (ME096). This polymer contains MBBs which have a general formula CdN2(CO2)4. The coordination spheres of Figure 3.11 ME096 consists of zig-zag chains that are built from one type of MBB, composed of cadmium and 4-imidazolecarboxylic acid. the cadmium metals are occupied by two dito pic linkers, one through chelation and the other through monodentate coor dination, a water molecule a nd a chelating terminal 4ICA ligand. Two coordinated donor atoms, the heterochelating nitrogen and the monodentate oxygen, are responsible for the topological outcome, resulting in a one dimensional chain. In contra st to what was targeted, the nitrogen in the 1 position of 4ICA was not deprotonated and the ditopic linker was not coordinated through both nitrogen atoms of the ligand. Instead, onl y the 3-position nitrogen and the 4-position carboxylate oxygen atoms of 4-ICA coordinate to the cadmium center. Additionally, the neutral chains pack ABAB in a head to tail manner, to form layers. The layers pack ABAB and DMF guests reside between the layers. Another solvothermally synthesized cr ystal, containing cadmium and 4-ICA {[Cd(4-IMC)2]}n (ME086), is constructed from a CdN2(CO2)4 MBB. Each metal center

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37 is coordinated by four ligands, two of which are monodentate oxygen atoms while the other two heterochelate through nitrogen a nd oxygen atoms the metal node, which results in a MBB with the formula MN2(CO2)4. Once again, the 1-pos ition nitrogen of 4-ICA was not deprotonated under these conditions, so the linker did not act as the 145 ditopic linker as expected, instead the bridging carboxyl ate further extend the structure into a 3-D MOM with dia -like topology. As mentioned earlier, the dia net is a regular net and thus highly expected when structure direc ting building blocks lack rigidity. Figure 3.12 4-IMC and cadmium ions are used to form a dia net from MN2(CO2)4 MBBs. It should be noted that ME096 and the ME086 can be assembled under the same reaction conditions under different temperatuers When identical amounts of reagents are added to two different vials a nd one is heated at 85C for 12 hours and the other is heated at 105C for 23 hours ME096 and the ME086 are fo rmed respectively. If the first vial containing ME096 is heated to 105C the zig-zag chains ar e converted into the cubic diamond-like topology, ME086.

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38 Previously, it has been proven feasible to synthesize assemblies that are isoreticular with indium-based assemblies, constructed from single-metal ion-based MBBs MN2(CO2)4, using cadmium ions as the singlemetal nodes in an instance where isoreticular metal-organic octahedra were produced with both metals. A 2-D cadmiumbased framework (ME207) has been synt hesized, using cadmium nitrate and 2,5pyridinedicarboxylic acid, that is isoreticular with an indium-based Kagom-like MOF.2 In both cases, the MN2(CO2)4 MBB results from nitrogen atoms coordinating in a cis fashion with rings of chelation that are 90 apart, which coincides with a MN2O2 BU. Figure 3.13. 2,5-PDC and cadmium ions can be used to construct a kag net from MN2O2 BUs resulting from MN2(CO2)4 MBBs The crystal structure of ME207 contains large disordered guest molecules, which are likely imidazole and dimethylammonium cations to balance th e anionic network, induced by from the 2:1 ratio of deprotonated [2,5-PDC]2to Cd2+ ions. The 2-D

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39 Kagom-like sheets stack relatively densel y in an abcabc fashion, with no apparent channels. 3.3.3 MOMs Containing MN3O3 Building Units Figure 3.14. 4,5-IMDC and cadmium ions have been used to create a metal-organic cube from a facMN3(CO2)3 MBB. As mentioned earlier, the metal-nitrogen bonds of the facMN3(CO2)3 MBB, the MN3 BU, constitute the corner of a cube and can be employed in the edge-directed assembly of an anionic metal-organic cube.73 It has since been prove n that other singleindium metal ion-based MBBs can be synthesi zed with cadmium ions, and can be applied to recreate other single-meta l ion-based MBBs, specifical ly using 4,5-IMDC as the heterchelating linker. A preliminary crystal structure of ME299 indicates that a nickelbased MOC has been recreated with cadmium n odes. As the versatile packing of MOCs can result in open or dense te rtiary structures, this cadmi um-based MOC exhibits cubic closest packing in an ABCABC fashion. Such packing results in a dense structure devoid of channels and cavities.

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40 3.3.4 Heterocoordinated Metal-Organ ic Frameworks from MBBs Nets based on one type of MBB are commonly crystallized, however, MOMs constructed from multiple types of MBBs can also be accessed. As the structures were unexpected, since the metals and ligands used are generally intended for the formation of predictable nets from one type of MBB, there is much to be learned from these examples. Such reaction conditions allowed th e avoidance of envisioned nets via crystallization in topologies of higher transitivities. The focus will be nets containing 3and 4-coordinate vertices. Reaction of cadium acetate and 4,5-IMDC yields a 3-D MOF, JB9545, that is built from two 3and one 4-connected MBBs. A tritopic 4,5-IMDC ligand, that coordinates through a monodentate nitroge n, N-, and Oheterochelation, and a monodentate oxygen connection. The other two MBBs are single-metal ion-based and Figure 3.15. JB9545 is constructed from three types of MBBs yielding a net with unprecedented toplogy, which contains [62.74.84.94] tiles.

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41 related to previous examples. The 4-connected single-metal ion-based CdN2(CO2)4 MBB, from a transCdN2O4 ion, exhibits cischelation and thus a see-sawlike BU, with nitrogen atoms in the fulcrum positions and oxygen atoms on the lever postions. The 3connected MN2(CO2)3 MBB consists of a single metal ion coordinated by three 4,5IMDC ligands, two through N-, O-heterchela tion and one through a monodentate oxygen connection, resulting in a trigona l planar BU. The sphere of coordination is completed by a terminal DMF or DMA molecule coor dinated through a carb oxylate oxygen atom. Topologically, there are five different t ypes of nodes, a metal-based 4-connected node (vertex symbol: 6.7.7.8.12(2)) and four diffe rent types of 3-connected nodes (vertex symbols: 6.7.8; 7(2).8.9(2); 7.7.8; 6.8.9(2)), of which two are ligand-based and two are metal-based, which composes an unprecedente d topology, to the best of our knowledge. The net is tile transitive a nd is constructed two 6MRs, four 7MRs, four 8MRs, and four 9MRs. The networks consists of a two dimensional channel system from 6MRs, however, coordinated terminal ligan ds block access to the channels. In another reaction between cadmium acetate and 4,5-IMDC an anionic, 3-D MOF with extra-large unidimensional channe ls was crystallized, namely, ME688. Two types of molecular building blocks. The CdN3(CO2)3 MBB consists of three 4,5-IMDC ligands that heterochelate th rough N and O donor atoms, and the N atoms, in a facial arrangement, constitute and 3-connected BU. The CdN4 MBB is formed through the coordination of four 4,5-IMDC ligands through n itrogen atoms, which can be viewed as a

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42 Figure 3.16. 4,5-IMDC and Cd are used to construct a (3,4)-net with unprecedented topology from two types of MBBs. The binodal network is built from four types of tiles. tetrahedral BU. The 3-coordinate node has a coordination sequence of 3, 7, 11, 17, 28, 38, 52, 78, 92, 104, short (Schlafli) vertex sym bol: 4.6.8, and long topological (O'Keeffe) vertex symbol: 4.6.10(4). The 4-coordinate node has a coordination sequence 4, 6, 11, 20, 26, 40, 60, 70, 91, 116, short (Schlafli) ve rtex symbol: 4(2).6.8(2).10, and long topological (O'Keeffe) vertex symbol: 4.4.6.10(4).10( 2).10(2). In this unprecedented net, the 3and 4-coordinate node s facilitate the formation of 4-, 6-, and 10-MRs with

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43 accessible windows of approximately 2.75, 7.7, and 6.5 x 18.6, respectively. The 4-, 6-, and 10MRs constitute the walls of unidime nsional channels with an approximate diameter of 15 along the z-axis, while smaller cha nnels are accessible through the xand y-axes. This open anioni c material is capable of i on-exchange of large organic molecules, such as acridine yellow (Appendix III). These examples show that MBBs based on heterochelating ligands can be used to access MOFs with heterocoordination, or mixed types of nodes. Although these types of nets are challenging to predict and/or cons truct from design, these occurrences allow insights to capabilities and further design advancements. 3.4 Summary & Conclusions This class of compounds illustrates th at varied modes of heterochelation combined with ligand angularity directs th e formation of numerous nets. Overall, Figure 3.17. Molecular building blocks, constructed from MNxOy ( x + y = 6) single-metal ions can facilitate the formation of various metal-organic materials.

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44 combining the approaches of nitrogen-ba sed and carboxylate-ba sed ligands, which exploit hetero-chelation invol ving nitrogen and oxygen, in th e deliberate synthesis of MOFs from single-metal-ion-based MBBs, is an effective method of synthesizing discrete and extend ed metal-organic assemblies. Thus far, certain MBBs, and consequential BUs, predominate and dictat e the formation of certain structures. Exploration of advancing this approach to other metal coordination modes, MNx(CO2)y, and discovering common conditions to formul ate projected frameworks will continue to advance the design of such materials.

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45 Chapter 4: Design of Zeolitelike Metal-Organic Frameworks Zeolites are currently the largest cla ss of commercially available functional porous materials. Zeolites ar e classically defined as exclusively aluminosilicate, threedimensional, open frameworks consisting of corner-sharing [AlO4]5and [SiO4]4tetrahedra with the general formula Mn+ x/n[(AlO2)x(SiO2)y]xw H2O, capable of ion exchange and reversible dehydration.80 Naturally occurring zeolites have been studied for over 200 years, while research of the synt hesis of zeolites has been progressing for over 140 years.81 Zeolites, which have high ther mal stabilities, can contain multidimensional as well as unidimensional por e systems, or channels. The pores have molecular dimensions and are able to accommodate small guest molecules. Although unidimensional pore systems are appropriate fo r some applications, the bulk of zeolitic research is focused on frameworks consisting of multidimensional pore systems. Zeolite research is captivating due to a variety of applicatio ns, including catalysis, ion exchange, gas storage, pur ification and separation, etc.82 mainly resulting from permanent porosity and intrinsic declination of interpenetration. Specific applications include recovery of radioactiv e ions from waste solutions,83 separating hydrogen isotopes, solubilizing enzymes, carrying active catalys ts in the curing of plastics and rubber, transporting soil nutrients in ferti lizers, hydrocarbon conversion catalysis,84-85 and silicon nanowire synthesis.86 Zeolites have proven futile for so me applications, such as methane storage, separation/catalysis of large mo lecules, molecular magnetism, and hydrogen storage.

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46 Figure 4.1 A few zeolite frameworks are illustrated to display the porous nature of the naturally occurring aluminosilicate compounds. left : faujasite ( fau ) center : Linde Type A ( lta ) right : AlPO4-5 ( afi ) Zeolites are commercially used for ion exchange.82,84,87 The presence of aluminum in the silicate lattice induces a negative charge within the framework. The anionic framework is compensated by cationic gue sts that are present within the pores or channels. These intrinsic anionic properties allow ion-exchange to occur, which highly impacts possible commercial applications. The capacity for reversible cation-exchange is very important in zeolites because it allows manipulation of the electronic atmosphere inside pores. Sorption properties are dependant on the cations present within the cavities. For example, when the sodium cations present in the pore system of the zeolite Linde Type A ( lta ) are replaced with potassium cations the sorption capacity for oxygen is essentially eliminated. It is also appa rent that propane is not sorbed by the lta zeolite that contains sodium, however, when the sodium ions are exchanged with calcium, lta is capable of propane sorption. Cation-exchange in zeolites is also in fluential on catalytic properties and sepa ration capabilities.84 An arduous objective is to increase pore sizes of multidimensional channel systems of zeolite-like materials and design frameworks that possess tunable properties and novel functionalities that exceed the boundaries of currently available porous

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47 materials. The potential for design of MOMs offers a means to expand zeolitic frameworks and thus further develop applic ations based on solidstate materials. 4.1 Zeolitelike Metal-Organic Frameworks from Supermolecular Building Blocks The ability to control c oordination number, and t hus geometry, around metal nodes through metal-ligand directed assembly affords the sy nthesis of pre-designed finite and rigid metal-organi c polyhedra (MOPs).4,23,67,73,88 MOPs with peripheral functionalities can be employed further as supermolecular building blocks (SBBs) in the construction of extended meta l-organic frameworks (MOFs).89-90 This approach is illustrated in the construction of rht -MOF, in which a metal-organic nanoball (cubohemioctahedron) is periphera lly functionalized with tetr azole groups that form a trimeric metal cluster. Essentially, the network is synthesized using 5tetrazolylisophthalic acid and copper nitrate. Just as the cubohemioctahe dron can be functionalized and, thus, extended, various othe r MOPs with appropriately placed points of extension can be used as augmented vers ions of defined nodes with high connectivity. Programming such building blocks with a hierarchy of appropriate information to promote the synthesis of targeted structures, while simultaneously avoiding other easily attainable nets,91 represents a significant advancement in framework design.28 In crystal chemistry edge transitive nets are suitable targets for such processes, since they are simple networks composed fr om only one kind of edge. Our pre-designed finite metal-organic cube MOC73 can be employed as a rigi d and directional SBB for the directed assembly and deliberate construc tion of extended MOFs based on 8-connected edge transitive nets. According to the RCSR,50 only five 8-connected nets are edge

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48 transitive, bcu, bcu-b, lcx, reo, and thp Of these basic nets, bcu and reo are closely related to zeolite nets, specifi cally, the augmentation of the 8-connected nodes result in zeolite nets aco and lta A particular subset of zeolite nets sh are a common secondary building unit (SBU) composed of eight tetrahedra bridged thro ugh oxide ions in a cube-like arrangement, commonly referred to as a double 4-ring, d4R.81 The analogy of this SBU to a cube (and, by default, a MOC) suggests that MOCs could be used as SBBs to target zeolite nets based on d4Rs. Figure 4.2. ast, aco, asv, and lta are zeolitic nets closely related to basic 8-connected nets, and thus exceptionally interesting to metal-orgaic crystal chemistry. Our approach encompasses using MOCs as 8-connected building blocks, which can be regarded as d4Rs to construct ZMOFs relate d to 8-connected edge-transitive nets. The d4Rs can be connected through linear lin kers to construc t zeolite-like nets As previously described, a metal-orga nic molecular cube can be assembled through hetero-chelation of octahedral single-m etal ions by ditopic bis-bidentate linkers in a fac -MN3(CO2)3 manner,. The molecular cube itsel f consists of eight vertices

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49 occupied by tri-connected nodes bridged through twelve 4,5-imid azoledicarboxylate (HnImDC, n = 0-1) linkers. By the coordinati on of such vertic es, interconnected tetrahedra similar to the D4R units in zeolites can be attained. The MOCs possess peripheral carboxylate oxygen atoms that can pot entially coordinate a dditional metal ions and/or participate in hydrogen bonding to construct ZMOFs. 4.1.1 Experimental All chemicals were used as received fr om Fisher Scientific, Sigma-Aldrich, and TCI America chemical companies. Fourier transform infrared (FT-IR) spectra were measured using an Avatar 320 FT-IR system. Absorptions are described as follows: very strong (vs), strong (s), medium (m), weak (w), shoulder (sh), and broad (br). X-ray powder diffraction (XRPD) data were re corded on a Rigaku RU15 diffractometer at 30kV, 15mA for CuK ( = 1.5418 ), with a scan speed of 1/min and a step size of 0.05 in 2 Calculated XRPD patterns were pr oduced using PowderCell 2.4 software. Single-crystal X-ray diffraction (SCD) data were collected on a Bruker SMART-APEX CCD diffractometer using MoK radiation ( = 0.71073 ) operated at 2000 W power (50 kV, 40 mA). The frames were integrated with SAINT software package74 with a narrow frame algorithm. The structure was solved using direct methods and refined by fullmatrix least-squares on | F |2. All crystallographic calculations were conducted with the SHELXTL 5.1 program package,75 and performed by Dr. Vict or Kravtsov, Dr. Lukasz Wojtas, Dr. Derek Beauchamp, Dr. Rosa Walsh or Gregory J. McManus in the Department of Chemistry at the University of South Florida. Crysta llographic tables are included for each compound in Appendix I

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50 Olex76 and Topos77 software was used to determin e topological representations of the obtained MOMs, and the resulting terms comp ared to those in the literature and the RCSR database.50 All total solvent-accessible volumes were determined using PLATON78 software by summing voxels more th an 1.2 away from the framework. Tiling was evaluated using 3dt software.79 Synthesis of C634H414N234O807Cd72Na72, ME500 H3ImDC (0.087 mmol, 13.6 mg), Cd(NO3)2 4H2O (0.0435 mmol, 13.4 mg), N,N’-diethylformamide (1 ml), ethanol (0.25 ml), piperazine (0.1 ml, 0.58 M in DMF), sodium hydroxide (0.1 ml, 0.174 M in ethanol), and 2,4-pentanedione (0.1 ml, 0.174 M in ethanol) were adde d to a 25 ml scintillation vial, which was then sealed, heated to 85 C and cooled to room te mperature at a rate of 1 C/min to produce colorless, hexagonal prism-like crystals formulated as C634H414N234O807Cd72Na72 with a 67% (0.0137 g) yield based on ?. FT-IR (4000–600 cm1): 1650.25 (w), 1622.59 (w), 1548.82 (s), 1484. 49 (vs), 1437.5 (s), 1379.16 (s), 1298.34 (m), 1253.75 (m), 1217.09 (w), 1110.98 (m), 997.18 (w), 975.02 (w), 846.39 (w), 786.95 (s), 667.49 (vs), 655.87 (vs), 613.00 (s) 4.1.2 Results & Discussion Reaction of Cd(NO3)2.4H2O and H3ImDC in the presence of Na+ ions results in ltaZMOF, formulated as {[Cd8(HImDC)8(ImDC)4](H2Pip)2Na8(EtOH)5(H2O)37} (Pip=Piperazine, EtOH=Ethanol). In the crystal structure of lta -ZMOF, each MOC is linked to eight other cubes through linear vertex-to-vert ex connections. Half are connected through hydrogen bonded water molecu les and the other four vertices are connected through a series of four sodium at oms, Figure 4.3. The framework consists of

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51 two types of cages, namely an -cage encapsulated by 12 cubes and an elliptical -cage enclosed by 6 cubes. The largest sphere that can fit into these cages without touching the van der Waals surface of the framework is ~32 for the -cage and ~8.5 for the Figure 4.3. In ltaZMOF, twelve MOCs are connected through a series of sodium ions (top left) to generate an -cage (tile shown in green) that can accommodate a sphere with diameter of ~32 and 6 MOCs assemble a -cage (tile shown in yellow) that can fit a sphere of ~8.5 in diameter. cage. Topologically, the framework can be viewed as lta or an augmented version of reo when the hydrogen bonded and sodium bridged vertex-vertex connecti ons are considered. However, the structure can be interpreted as nbo if only connections through sodium ions are considered. This work demonstrates that utilization of MOPs as SBBs represents an interesting approach towards rational design and synthesis of nanostructures. MOCs, the

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52 MOPs of significance, offer the potential to target and build zeolitic frameworks containing d4Rs. The aforementioned SBBs cont ain a hierarchy of information regarding the evolution of single metal ions, with anticipated coordi nation geometries, deemed as rigid and directional vertices, via heterochelatio n, into MOPs that can be used as defined high-connected building blocks to yield zeolitic frameworks. 4.2 Zeolitelike Metal-Organic Frameworks from MNx(CO2)y Molecular Building Blocks To date, MN4O4, MN4O2, 65, 92 and MN4 51 MBBs have been observed in metalorganic zeolite-like materials constructed from imidazoleor pyrimidine-based linkers. Consistently, in all cases the TBUs are of the general formula MN4 in which the nitrogen atoms direct the topology. It is conceivable that th e points of extensi on in the tetrahedron can be interchanged with atoms, other than nitrogen, in an aim to target nets uncommon in metal-organic crystal chemistry. MN4O2 and MN4O4 MBBs, which correspond to MN4 TBUs, have been built from 8and 6coordinate metal nodes respectively, and ligands that form 5MR of heterochelation to the metal center through nitrogen and carboxylate-oxygen atoms. Additionally, MN2O4 MBBs, from 6-coordinate metals, predictably form MN2O2 TBUs in which two nitrogen atoms (participating in heterchelation) and two monode ntate oxygen atoms direct the topology. To facilitate the formation of such TBUs, it is desirable to avoid MBBs that solely consist of heterochelation and/or monodent ate nitrogen coordination. Therefore, when scheming the heterochelating ligand that forms MN2O2 building units, an assymetric ditopic ligand with a site appropriate for N-, O-heterche lation and a bridging ca rboxylate group is appropriate. When the MN2O2 TBUs are intended to be used to construct ZMOFs, the

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53 angle through which they are connected wi ll ideally correspond to the optimal T-O-T bonding angles exhibited in trad itional zeolites, as is 2,4-Pyridinedicarb oxylic acid (2,4H2PDCA). 4.2.1 Experimental All chemicals were used as received from Fisher Scientific, Sigma-Aldrich, and TCI America chemical companies. Fourier transfor m infrared (FT-IR) spectra were measured using an Avatar 320 FT-IR system. Absorptions are described as follows: very strong (vs), strong (s), medium (m), weak (w), shoulder (sh), an d broad (br). X-ray powder diffraction (XRPD) data were recorded on a Rigaku RU15 diffractom eter at 30kV, 15mA for CuK ( = 1.5418 ), with a scan speed of 1/min and a step size of 0.05 in 2 Calculated XRPD patterns were produced us ing PowderCell 2.4 software. Single-crystal X-ray diffraction (SCD) data were co llected on a Bruker SMART-APEX CCD diffractometer using MoK radiation ( = 0.71073 ) operated at 2000 W power (50 kV, 40 mA). The frames were integrat ed with SAINT software package74 with a narrow frame algorithm. The structure was solved using direct methods and refined by fullmatrix least-squares on | F |2. All crystallographic calculations were conducted with the SHELXTL 5.1 program package,75 and performed by Dr. Vict or Kravtsov, Dr. Lukasz Wojtas, Dr. Derek Beauchamp, Dr. Rosa Walsh or Gregory J. McManus in the Department of Chemistry at the University of South Florida. Crysta llographic tables are included for each compound in Appendix I Olex76 and Topos77 software was used to determin e topological representations of the obtained MOMs, and the resulting terms comp ared to those in the literature and the RCSR database.50 All total solvent-accessible volumes were determined using

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54 PLATON78 software by summing voxels more th an 1.2 away from the framework. Tiling was evaluated using 3dt software.79 Synthesis of {In(2,4-PDC)2]}n, ME654 : A solution of In(ac)3H2O (0.0435 mmol) and 2,4-PDC (0.087 mmol) in 1 mL of DEF, 0.5mL of ethanol, and 0.1mL of 1M tetrabutylammonium sulfate in water was prepared. The solution was then heated to 85C for 12 h, pure colorless crysta ls were obtained. FT-IR (4000-600 cm-1): 3386(br), 3109(br), 2350(m), 1653(s), 1600(m), 1485( m), 1431(s), 1380(vs), 1248(s), 1100(s), 1057(s), 785(s), 754(s), 7 27(vs), 657(s), 614(s). Synthesis of {In(2,4-PDC)2]}n, ME658 : A solution of In(ac)3H2O (0.0435 mmol) and 2,4-PDC (0.087 mmol) in 1 mL of DMA, 0.5mL of ethanol, and 0.1mL 1.6M diethylamine in DMF was prepared. The solu tion was then heated to 85C for 12 h, pure colorless crystals were obtained. FT-IR (4000-600 cm-1): 3386(br), 3109(br), 2350(m), 1653(s), 1600(m), 1485(m), 1431(s), 1380(vs), 1248(s), 1100(s), 1057( s), 785(s), 754(s), 727(vs), 657(s), 614(s). 4.2.2 Results & Discussion Overall, combining the a pproaches of nitrogen-bas ed and carboxylate-based ligands, in the deliberate synthesis of MO Fs, into single-metal-ion-based MBBs, which exploit heterochelation i nvolving nitrogen and oxygen, is an effective method of synthesizing discrete and ex tended metal-organic assemblie s. Thus far, certain MBBs, and consequential SBUs, predominate and dict ate the formation of certain structures. Exploration of advancing this approach to other metal coordination modes, MNx(CO2)y,

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55 and discovering common conditions to formul ate projected frameworks from specific MBBs is currently under development. He rein, two novel ZMOFs constructed from 2,4PDC and Indium, namely ana -ZMOF and sod -ZMOF-1 are presented. Figure 4.4. An MN2(CO2)4 molecular building block can be exploited as an MN2O2 tetrahedral building unit. In crystal design, the formation of regular nets is common, and sometimes unavoidable. Furthermore, of zeolite nets, those with high er regularity are reasonable targets. While there are no re gular or quasiregular zeolite ne ts, sodalite and analcime are the only two examples of zeolitic nets that are semiregular. Sodalite and analcime have transitivities of 1121 and 1132, respectively. Both structures consist of one type of vertex (vertex transitive) and one type of edge (edge transitive). Additionally, these nets are the only edge transitive zeolite nets. Such regular ity deems sodand ananets as suitable targets in crystal chemistry, and due to the tile-transitivity of sod, it is especially plausible. InN2O4 MBB InN2O2 TBU

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56 The ana net consists of irregular 3-dime nsional channels formed by highly distorted 8MRs, and is composed of two type s of tiles, one with two hexagonal and three Figure 4.5. Tiles of ana net are constructured from two hexagons, three octagons (yellow), and two quadrangles and two octagons (green). octagonal faces and the other from two tetragonal and two octagonal faces. In anaZMOF, InN2O2 BUs replace tetrahedral atoms of inorganic analcime, and are linked through the doubly deprotonated bridging lig and, 2,4-pyridinedicarboxylate (2,4-PDC), which is an expansion of the oxygen bridges of T-O-T in zeolites. The resulting anionic structure has dimensions appropriate for ionexchange of large organic cations, such as acridine yellow (Appendix III). [62.83] [42.82]

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57 Figure 4.6. 2,4-PDC and indium ions can be used to construct ZMOFs related to ana and sod nets. In the structure of sodZMOF(1) the sodalite net is assembled from highly distorted -cages built from 4MRs and planar a nd chair-like 6MRs, and the distortions allow for the encapsulation of larger molecule s than analogues with regular cages. For example, a sod-ZMOF constructed from In3+ and 4,6-pyrimidinedicarboxylate,92 with regular cages, has proven capable of excha nging small inorganic cations, however, is resistant to the adsorption of larger acridi ne molecules. This comparison provides evidence that by altering just one atom of a ligand, the atoms/points of extension of the building unit can be controlled, and the prop erties of the resultant material can be delicately tuned.

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58 a) b) Figure 4.7. a) optical images of ion-exchange in anaZMOF with acridine orange. b) optical images of ion-exchange in sodZMOF. 4.3 Zeolitelike Metal-Organic Frameworks Organic Tetrahedral Nodes Metal-organic tetrahedral building un its (TBUs) can be connected through appropiate angles to faciliate the expans ion of the Si/Al nodes and oxide atom (O2-) bridges of zeolites and, ultimately lead to non-interpenetrated, enlarged, multidimensional pore systems and/or ca vities. Our group, among others, has demonstrated that metal-organic TBUs can be designed an d exploited in the construction of various ZMOFs.65,92 In an effort to extend this innovation to other unprecendented ZMOFs, we deliberate the us e of purely organic TBUs. Previously, HMTA, containing accessible N-donor atoms in a tetrahedral arrangement, has been deemed as an appropriate TBU. The rema ining resulting challenge is to utilize metal coordination to bridge the TBUs at an angle analogous to th e bonding angle of O2found in zeolites. N N N Acridine orange N H2N NH2 Acridine yellow N Br 9-(methylbromo)-acridine N N N

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59 Organic ligands can be selected to induce directionality in framework design. For instance, hexamethylenetetramine (HMTA) c ontains nitrogen atoms in a tetrahedral arrangement that can be utilized to position coordinated metals at approximate 109.5 angles. Additionally, metals of high coor dination can be employed as 2-connected linkers while small terminal ligands, such as acetate and water, can complete the sphere of coordination. Exploration of reaction conditions involving such variables can lead to the realization of networks, constructed from organic tetr ahedral nodes, with tunable ionic strength and interesting topologies. Previously, hexa methylenetetramine (HMTA), containing N-donor atoms in a tetrahed ral arrangement, has been deemed as a suitable TBU. The remaining challenge is to utilize metal coordinati on, as a function of auxiliary ligands, to bridge the TBUs at an angle analogous to the bonding angle of O2found in zeolites. Cadmium (Cd2+) has previously exhibited the desired bond angle, when coordinated by HMTA, to assemble a net with mtnlike topology.93 In this example, HMTA ligands coordinate to the axial postions of each cadmium ion and three equatorial positions are occupied by water molecules, resulting in a cationic network. It is feasible that replacement of the water molecules with ot her small, terminal ligands assists in slight variations of appropriate N-Cd-N bond angles to achieve an assortment of zeolitelike topologies. Additionally, the ch arge of the framework can be controlled by varying the ionic nature of the selected auxiliary ligands. Whereas three auxiliary water ligands yielded a cationic framework, systematic repl acement with anionic ligands can produce cationic, neutral or anionic frameworks. As the ionic nature of the framework can be controlled, ionic structure di recting agents can be varied to access unprecedented

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60 ZMOFs. Herein, a rare coordination sphere of cadmium is occupied by three equatorial acetate ions and two nitrogen atoms in the axial positions, from HMTA ligands, to construct three anionic ZMOFs. The acetate anions simultaneously complete the coordination sphere of the cadmium linker, a llow the formation of suitable N-Cd-N bond angles, and contribute to the ionic nature of the framework, which may be exploited in ZMOF design. Reaction conditions for the synthesis of anionic mep -ZMOF, using HMTA as an organic TBU and a cadmium ion as an angular linker, was fortuitously discovered. Consequently, it was determined that varying cationic structure directing agents (SDAs), under similar conditions, allo wed consistant access to appropriate N-CdN angles, and ultimately unprecedented ZMOFs related to sod and mtn topologies. Figure 4.8. The nitrogen atoms (blue) of hexamethylenetet ramine, situated in a tetrahedral arrangement, can coordinate to metal ions to act as a tetrahedral building unit, and, when connected through appropriate angles (as shown in green), can facilitate the formation of zeolitelike metal-organic frameworks. 4.1.1 Experimental All chemicals were used as received from Fisher Scientific, Sigma-Aldrich, and TCI America chemical companies. Fourier transfor m infrared (FT-IR) spectra were measured using an Avatar 320 FT-IR system. Absorptions are described as follows: very strong

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61 (vs), strong (s), medium (m), weak (w), shoulder (sh), an d broad (br). X-ray powder diffraction (XRPD) data were recorded on a Rigaku RU15 diffractom eter at 30kV, 15mA for CuK ( = 1.5418 ), with a scan speed of 1/min and a step size of 0.05 in 2 Calculated XRPD patterns were produced us ing PowderCell 2.4 software. Single-crystal X-ray diffraction (SCD) data were co llected on a Bruker SMART-APEX CCD diffractometer using MoK radiation ( = 0.71073 ) operated at 2000 W power (50 kV, 40 mA). The frames were integrat ed with SAINT software package74 with a narrow frame algorithm. The structure was solved using direct methods and refined by fullmatrix least-squares on | F |2. All crystallographic calculations were conducted with the SHELXTL 5.1 program package,75 and performed by Dr. Vict or Kravtsov, Dr. Lukasz Wojtas, Dr. Derek Beauchamp, Dr. Rosa Walsh or Gregory J. McManus in the Department of Chemistry at the University of South Florida. Crysta llographic tables are included for each compound in Appendix I Olex76 and Topos77 software was used to determin e topological representations of the obtained MOMs, and the resulting terms comp ared to those in the literature and the RCSR database.50 All total solvent-accessible volumes were determined using PLATON78 software by summing voxels more th an 1.2 away from the framework. Tiling was evaluated using 3dt software.79 Synthesis of mep -ZMOF: Cd(Ac)2 •H2O (0.104g, 0.3915mmol), hexamethylenetetramine (0.100 g, 0.713mmol), DEF (2.25mL), ethanol ( 0.50mL) were combined in a 20-mL vial, which was sealed and heated to 85 C for 12h, 105 C for 23h and then cooled to room temperature. Colorless polyhedral crystals were collected and air dried, yielding 0.0657g

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62 FT-IR: 3308.92 (br), 2970.32 (m), 1657.01 (w), 1558.4 (s), 1417.75 (s), 1380.15 (s), 1232.11 (s), 1161.98 (w), 1130.1 (w), 1049.8 (w), 1001.39 (vs), 951.89 (m), 815.3 (s), 671.29 (s), 620.41 (s) Synthesis of sod -ZMOF(2): Cd(Ac)2 H2O (0.052g, 0.19575mmol), hexamethylenetetramine (0.050 g, 0.357mmol ), DMA (1.125mL), ethanol (0.125mL), water (0.25mL) tetramethylammoni um nitrate (0.05mL, 1M in H2O) were combined in a 20-mL vial, which was sealed and heated to115 C for 23h and cooled to room temperature. Colorless polyhedral crystals were collected and air dried, yielding 0.0798g. FT-IR (4000–600 cm-2): 3247.2 (br), 1562.73 (m), 1491.43 (w), 1417.59 (m), 1369.87 (w), 1345.83 (m), 1233.85 (m), 1222.91 (w ), 1049.1 (w), 1019.47 (m), 1000.59 (s), 947.3 (w), 833.17 (w), 811.06 (m), 799.99 (m), 778.81 (w), 706.98 (m), 670.69 (vs), 681.12 (s), 636.35 (w), 622.93 (m) Synthesis of mtnZMOF: Cd(Ac)2 •H2O (0.052g, 0.19575mmol), hexamethylenetetramine (0.050 g, 0.357mmol ), water (0.25mL), DEF (1.125mL), H2O (0.25mL), sodium acetylacetonate (0.25mL, 0.174M in ethanol) tetrabutylammonium bromide (0.05mL, 1M in H2O) were combined in a 20-mL vial, which was sealed and heated to105 C for 23h and cooled to room temperatur e. Colorless polyhedral crystals were collected and air dried, yielding 0.0295g. FT-IR (4000–600 cm-2): 3420.34 (br), 2968.2 (w), 2872.15 (w), 1660.03 (w), 1559.44 (m), 1418.31 (m), 1232.29 (m), 1111.4 (w), 1050.78 (w), 1001.01 (vs), 941.16 (w), 812.16 (m), 787.19 (w), 670.4 (s), 617.31 (s)

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63 4.1.2 Results & Discussion Reaction of cadmium acetate and HMTA in the presence of N,N’-diethylformamide and ethanol results in the formation of a mixture of mepZMOF and sodZMOF crystalline phases. Cadmium and diethylammonium cations are available for charge balance, and modification of such cation availability can direct the synthesis of different structures. Reaction of cad mium acetate and HMTA in an N,N’dimethylacetamide/eth anol/water solution containing tetramethylammonium nitrate generates a pure crystalline phase of sodZMOF, in which cadmium and tetramethylammonium act to balance the charge of the framework. Additionally, reaction of cadmium acetate and HMTA in the presence of N,N ’-diethylformamide, water, sodium acetylacetonate and tetr abutylammonium bromide produces a pure crystalline phase of mtn -ZMOF via the influence of sodium and tetrabutylammonium ions. This work demonstrates that, under specific conditions, varying SDAs can result in different ZMOFs built from HMTA -based TBUs connected through Cdbased linkers. The mep topology, named for the natural s ilica-based mineral melanophlogite, is composed of pentagondodecahedral ([512]) and tetrakaidecahedral ([51262]) cages. The [51262] cages, are fused though a comm on 6MR. The fusing 6MR and accompanying 12 5MRs cons titute 12-ring double cups 30 tetrahedral units, characteristic of the clathras il family. In this anionic mep -ZMOF, HMTA coordinates to four Cd ions with N-Cd bond distances of 2.38-2.57 and N-Cd-N bond angles of 173.543-180.0. It contains a [512] cage with a van der Waals surface that allows the accomodation of a sphere with an a pproximate diameter of 8. The [512] cage is built

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64 from 20 HMTA nodes and 30 Cd2+ linkers and has a -30 charge. The [51262] cage is large enough to fit a sphere, within the va n der Waals surface, approximately 8.4 in diameter. This cage consists of 24 HMTA-based TBUs and 36 Cd2+ linkers, each coordinated by 3 acetate anions, to yield a charge of -36. Cadmium linkers are Figure 4.9. mep -ZMOF is constructed from [512] (yellow) and [51262] (green) cages. coordinated by bidentate acetat e ions, while, in some cases one acetate ion exhibits monodentate coordination and the remain ing oxygen atom assists to hold two cadmium ions within 5MRs. The distance from the centroid of one TBU to the next is approximately 8.1 , while the distance between tetrahedral atoms in the inorganic mep zeolite is approximately 3.1, demonstra ting an expansion of approximately 2.6 times. The mep net has a transitivity of 3432, or 3,4,3, and 2 types of vertices, edges, faces, and tiles, respectively. The three t ypes of vertices correspond to coordination sequences: v1=4, 12, 26, 44, 64, 9 8, 144, 172, 222, 272; v2=4, 12, 24, 42, 67, 95, 133,

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65 177, 219, 277; v3=4, 12, 25, 42, 69, 100, 129, 176, 229, 277. The mtn net, also part of the clat hrasil family, consists of [51264] and [512] tiles, with the 12-ring double cup arrangement. The mtn and mep nets both have transisitivties of 3432, three types of nodes, 4 kinds of edges, three faces, and two tiles. The three types of vertices corres pond to the following coordination sequences: v1=4, 12, 24, 36, 64, 112, 132, 156, 222, 264; v2=4, 12, 24, 39, 66 103, 130, 168, 216, 274; v3=4, 12, 25, 43, 68, 95, 133, 177, 223, 274. The mtnZMOF is constructed from HMTA tetrahedral nodes and cadmium linkers, coordinated by three bidentate acetate ions, and each 5MR contains three sodium ions. The [51264] cage is composed of 28 HMTA nodes and 24 Cd linkers. N-Cd bond distances are within the range of 2.36378 and 2.45615 and N-Cd-N bond angl es of 173.815-180.0. Figure 4.10. mtn -ZMOF a) ball and stick representation (guests and acetate ions are omitted for clarity), b) view of net, and c) [512] (yellow) and [51264] (red) tiles. d) Ball and stick representation of sodZMOF, e) view of net and f) packing of [46.68] tiles. The sod -ZMOF reported herein is constr uctred from HMTA linked through cadmium ions with N-Cd bond distances of 2.43540 and N-Cd-N bond angles of 160.202 The distance between the centroid of one TBU to the next is 7.738, while the tetrahedral nodes in the aluminosilicate ze olite are about 3.143 apart, thus this sodZMOF is over twice as large as the pur ely inorganic analogue. The framework consists of -cages with adequate space to encapsula te a sphere of ~10 in diameter. Each -cage is constructed from 24 HMTA nodes and 36 cadmium

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66 linkers, resulting in a -36 charge that is balanced by Cd2+ ions in the 4MR windows and six tetramethylammonium ions in each cage. As in mepZMOF, acetate ions exhibit bidentate coordinate to the cadmi um linkers, while some display monodentate coordination and the remaining oxyge n atom assists in stabilizing Cd2+ ion guests. Figure 4.11. sod -ZMOF, constructed from cadmium and HMTA. This work demonstrates that cadmium ions can be coordinated by three acetate ions and two axial nitrogen atoms to link HMTA-based TBUs, resulting in anionic ZMOFs. Various zeolitelike topologies can be accessed by altering the types of cations that are present as SDAs in these metal-organic materials. 4.4 Conclusions Various organic ligands and single-metal ions can be used for the design of ZMOFs, however knowledge and access to appr opriate synthetic conditions is limited. Three approaches utilizing (1) metal-organi c cube-based SBBs, (2) single-metal ionbased MN2(CO2)4 MBBs, and (3) organic TBUs repres ent advancements in the design and synthesis of ZMOFs. Experimentation with appropriate metal-organic monomers resulted in intentional formation of buildi ng blocks and, ultimately, established reaction conditions for numerous zeo lite-like networks.

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67 Chapter 5: Conclusions and Future Outlook As approaches for MOM design converge with building block ideals, the ability to ultimately impose utilitarian design becomes feasible for construction of materials for intended functions. The research presented in this thesis is primarily concerned with advancing strategies for the construction of pre-designed metal-organic materials, and in summary, the following notions ha ve been demonstrated. Single-metal ion-based mo lecular building blocks, MNx(CO2)y, can indeed be successfully employed in the rational constr uction of 0-, 1-, 2, and 3-dimensional MOMs. N-,O-Heterochelating ligands can unify aspects of nitrogen based ligands and carboxylate based ligands to induce rigidity and directionality. Differences in orientations of chelation a nd coordination in MBBs, which can be influenced by reaction conditions, have structure di recting effects on networks. The metal sources and/or ligands in MBBs can be changed to create isoreticular nets. MN2O2 tetrahedral BUs can be derived from MN2(CO2)4 MBBs and employed in the synt hesis of ZMOFs, which are highly valuable targets. Additionally, metal-organic cubes, assembled from MN3(CO2)3 MBBs, can be used as SBBs in the construc tion of ZMOFs. Suitable zeolite targets in metal-organic crystal chemistry, for such S BBs, can be revealed by relationships with augmented edge transitive 8-connected nets. In addition, a rare coordination of cad mium has been accessed by coordination of organic-based tetrahedral nodes to create MN4(CO2)3 based MBBs for the directed

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68 Figure 5.1. Summary of structured from MNx(CO2)y Molecular Building Blocks. synthesis of ZMOFs. Anionic auxiliary ligan ds, specifically acetate, can be exploited for the synthesis of charged networks, and ultimately charge-balancing structure directing agents can be used to access various ZMOFs. This work demonstrates that highly valuable target nets can be reconstructed with metal-organic MBBs on expanded scales, crys tallized as pure phase s, and employed in ion-exchange applications. Ion-exchange capabilities mani fest opportunities to tune properties of crystalline materials for specifi c applications. As construction of designed materials is advanced, with approaches base d on building blocks, ma terials with tunable cavities and channel sizes can be obtained. Ideally reaction conditions can be established and used in future syntheses of specifically intended building blocks. Additionally, linker angularity can be adjusted to compensate fo r the geometrical attributes of commonly formed BUs. Such MOMs can be used as pl atforms for innumerable guests, resulting in materials with tunable properties.

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69 With the continuation of developments in design and synthesis correlations, MOMs offer a means to tailor-make functional solid state materials for specific applications. Such materials are highly bene ficial to areas includi ng, but not limited to, transportation, environmental technologies space exploration, microelectronics, catalysis, chiral separations, and biomedical and pharmaceutical applications. As aspects of design mature, correlations between spec ific MOMs and desired applications are becoming stronger.

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70 References 1 Rowsell, J.L.C., Yaghi, O.M., Microporous Mesoporous Mater. 2004, 73 3. 2. Barrett, C.S., Structure of Metals, 2nd ed. McGraw-Hill, New York, 1952 ,1. 3. Stein, A., Keller, S.W., Mallouk, T.E. Science 1993, 259 3101, 1558. 4. Kitigawa, S., Kitaura, R., Noro, S. Angew. Chem. Int. Ed. 2004 43, 2334. 5. Griffith, R. L. J. Chem. Phys. 1943 11 499. 6. (a) Munakata, M., Kurodasowa, T., M aekawa, M., Honda, A., Kitagawa, S. J. Chem. Soc., Dalton Trans. 1994, 19, 2771. (b)Yaghi, O.M., Li, H. J. Am. Chem. Soc. 1995 117, 10401. 7. Fujita, M., Kwon, Y. J., Washizu S., Ogura, K. J. Am. Chem. Soc. 1994 116, 1151. 8. Kinoshita,Y., Matsubara, I., Higushi, T., Saito,Y. Bull. Chem. Soc. Jpn., 1959 32 1221. 9. Hoskins, B.F., Robson, R. J. Am. Chem. Soc. 1989 111 5962. 10. (a) Carlucci., L., Ciani, G., Proserpio, D.M., Rizzato, S. Chem. Commun 2001 1198-1199. (b) Halder, G. J., Kepert, C. J., Moubaraki, B., Murray, K. S., Cashion, J. D. Science, 2002, 298, 1762. (c) Iwamoto T.. The Hofmann-type and related inclusion compounds. In: Atwood JL Davies JED, MacNicol, DD, editors. Inclusion Compounds: Structural Aspect s of Inclusion Compounds Formed by Inorganic and Organometallic Host Lattices. 1984 London: Academic Press. p 29. 11. Kondo,M., Yoshitomi, T., Matsuzaka, H., Kitagawa, S., Seki, K. Angew. Chem. Int. Ed. Engl. 1997 36 16, 1725. 12. Kondo, M., Shimamura, M., Noro, S., Minakoshi, S., Asami, A., Seki, K., Kitagawa, S. Chem. Mater. 2000 12, 1288. 13. Hoskins, B.F., Robson, R. J. Am. Chem. Soc. 1990 112 1546. 14. O.M. Yaghi, H. Li, J. Am. Chem. Soc, 1996 118 295.

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76 Appendices

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77 Appendix I: Crystallography Tables Compound ME086 ME089 ME096 Chemical Formula Cd(C4N2O2H3)2 Cd2(C5N2O4H)2 (C2N2H4)2.5 C3NOH7 Cd2(C4N2O2H3)2 (H2O)2(C3NOH7)2 Formula Weight 334.58 768.26 867.38 Temperature, K 100 100 100 Crystal System Orthorhombic Monoclinic Monoclinic Space Group Fdd2 P21/n C2/c a, 11.2859(18) 11.5625(8) 24.483(5) b, 19.388(3) 15.0527(10) 10.929(2) c, 8.3726(14) 17.0502(11) 12.810(3) deg 90 90 90 deg 90 95.9080(10) 113.619(4) deg 90 90 90 V, 3 1832.0(5) 2951.8(3) 3140.5(11) Z 8 4 4 gcm-3 2.426 1.729 1.834 , mm-1 2.395 1.504 1.433 F(000) 1296 1504 1728 Crystal Size, mm 0.09 x 0.11 x 0.12 0.1x0.1x0.1 0.1x0.1x0.1 range for data collection, deg 3.2 to 24.9 2.2 to 28.4 3.2 to 28.3 Limiting indices -7<=h<=13 -22<=k<=22 -9<=l<= 9 -14<=h<=15 -19<=k<=16 -22<=l<= 15 -20<=h<=30 -12<=k<=14 -16<=l<= 13 Reflections collected 1788 18457 7391 Unique Reflections 775 6833 3454 R(int) 0.033 0.06 0.056 Goodness-of-fit on F2 1.06 1.04 1.01 Final R indices R1=0.0213, wR2=0.0499 R1=0.0603, wR2=0.1525 R1=0.0522, wR2=0.1105 Max. and Min. Resd. Dens., e -3 0.36 and -0.39 2.55 and -1.17 1.43 and -1.22

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78 Appendix I (continued) Compound ME184 ME207 ME299 Chemical Formula Cd(C6N2O2H7)2 (Cd(C7O4NH3)2)3 Cd12(C5N2O4)18 Formula Weight 390.6 1327.9 4086.1 Temperature, K 298 100 298 Crystal System Orthorhombic Trigonal Trigonal Space Group P212121 R-3c R-3 a, 11.549(4) 16.178(3) 17.1507 b, 11.666(3) 16.178(3) 17.1507 c, 11.762(4) 52.30(2) 42.0808 deg 90 90 90 deg 90 90 90 deg 90 120 120 V, 3 1584.7(9) 11855(5) 10719.59 Z 4 6 2 gcm-3 1.638 1.501 1.379 , mm-1 1.397 0.879 1.248 F(000) 776 5261 4254 Crystal Size, mm 0.07x0.08x0.1 0.1x0.1x0.02 0.1x0.1x0.1 range for data collection, deg 2.5 to 25.1 1.6 to 22.0 Limiting indices -13<=h<=12 -12<=k<=12 -14<=l<= 10 -16<=h<=16 -16<=k<=17 -55<=l<= 34 Reflections collected 6550 12031 Unique Reflections 2704 1621 R(int) 0.106 0.166 Goodness-of-fit on F2 0.84 1.02 Final R indices R1=0.0558, wR2=0.1193 R1=0.0577, wR2=0.1107 Max. and Min. Resd. Dens., e -3 0.6 and -0.59 0.52 and -0.44

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79 Appendix I (continued) Compound ME511 ME694 Chemical Formula Cd(C5N2O4H2)(C2N2H4)In3(C7O4NH3)6 (C4N2H12)O12 Formula Weight 325.58 1664.12 Temperature, K 100(2) 293(2) Crystal System Tetragonal Hexagonal Space Group I41/acd R-3c a, 12.5699(12) 26.64(3) b, 12.5699(12) 26.64(3) c, 26.676(5) 40.83(6) deg 90 90 deg 90 90 deg 90 120 V, 3 4214.9(9) 25094(52) Z 16 12 gcm-3 2.052 1.321 , mm-1 2.078 0.9 F(000) 2544 9893 Crystal Size, mm 0.15x0.1x0.1 0.10 x 0.10 x 0.10 range for data collection, deg 1.8 to 25.2 2.14 to 15.86 Limiting indices -15<=h<=7 -15<=k<=15 -32<=l<=31 -11<=h<=20 -20<=k<=1 -31<=l<=12 Reflections collected 9724 3269 Unique Reflections 968 1316 R(int) 0.023 0.1538 Goodness-of-fit on F2 1.494 1.148 Final R indices R1 = 0.0596, wR2 = 0.1436 R1 = 0.1283, wR2 = 0.3284 Max. and Min. Resd. Dens., e -3 0.970 and -1.164 0.872 and -0.726

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80 Appendix I (continued) Compound JB9545 ME688 Chemical Formula Cd0.75(C5N2O4H) (C3NOH7)0.75 Cd0.6(C5N2O4H)(C4N2) Formula Weight 300.4 298.71 Temperature, K 100 100 Crystal System Monoclinic Trigonal Space Group P21/c R-3m a, 14.725(6) 37.907(18) b, 14.664(5) 37.907(18) c, 23.550(9) 31.72 deg 90 90 deg 106.678(6) 90 deg 90 120 V, 3 4871(3) 39473(36) Z 16 90 gcm-3 1.639 1.131 , mm-1 1.379 0.780 F(000) 2348 13038 Crystal Size, mm 0.09x0.12x0.15 0.06x0.06x0.06 range for data collection, deg 1.8 to 25.14 2.21 to 21.5 Limiting indices -17 to 17 -9 to 17 -27 to 26 -20 to 37 -38 to 38 -24 to 32 Reflections collected 24232 23271 Unique Reflections 8611 5329 R(int) 0.15 0.175 Goodness-of-fit on F2 S=1.011 S=1.102 Final R indices R1=0.1100, wR2=0.2659 R1=0.1310, wR2=0.3159 Max. and Min. Resd. Dens., e -3 1.642 and -1.145 1.141 and -1.658

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81 Appendix I (continued) Compound ana -ZMOF (ME654) sod -ZMOF(2) (ME658) Chemical Formula In0.5(C7NO4H3) In0.5(C7NO4H3)(C)(O) Formula Weight 327.68 262.14 Temperature, K 187 293(2) Crystal System Cubic Hexagonal Space Group Ia-3d R-3 a, 37.469(16) 35.305(5) b, 37.469(16) 35.305(5) c, 37.469(16) 35.305(5) deg 90 90 deg 90 90 deg 90 120 V, 3 52604(39) 17300 Z 96 36 gcm-3 0.978 0.906 , mm-1 0.577 0.647 F(000) 15462 4619 Crystal Size, mm 0.1x0.1x0.1 0.1x0.1x0.1 range for data collection, deg 1.53 to 17.08 1.99 to 20.82 Limiting indices -18 to 21 -7 to 32 -13 to 32 -75 to 35 -35 to 32 -15 to 15 Reflections collected 9218 19560 Unique Reflections 1324 4021 R(int) 0.1391 0.1043 Goodness-of-fit on F2 1.240 1.161 Final R indices R1=0.1186, wR2=0.3150 R1=0.1415, wR2=0.3438 Max. and Min. Resd. Dens., e -3 0.483 and -0.538 1.049 and -1.124

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82 Appendix I (continued) Compound mep -ZMOF (ME474) sod -ZMOF (ME312) ltaZMOF (ME500) Chemical Formula CdC4.14N4O0.53H8 Cd2.50 C21.04 N5 O17.19 H43.084 Cd4(C5O4N2H2)4 (C5O4N2H)(C4N2H12)0.5 Na4(C2H5OH)1.25 (H2O)9.25 Formula Weight 234.52 917.77 943.69 Temperature, K 163(2) 100(2) 100(2) Crystal System Cubic Cubic Trigonal Space Group Pm-3n Im-3m R-3m a, 34.0147 21.8867(14) 40.637(5) b, 34.0147 21.8867(14) 40.637(5) c, 34.0147 21.8867(14) 39.063(7) deg 90 90 90 deg 90 90 90 deg 90 90 120 V, 3 39355.01 10484.3(12) 55865(13) Z 188 12 36 gcm-3 1.860 1.744 1.01 , mm-1 2.545 1.588 0.751 F(000) 21242 5491 16561 Crystal Size, mm 0.10 x 0.10 x 0.10 0.10 x 0.10 x 0.10 0.10 x 0.10 x 0.10 range for data collection, deg 2.54 to 19.19 2.28 to 23.23 1.74 to 20.05 Limiting indices -29<=h<=28, -11<=k<=31, -29<=l<=31 -23<=h<=24 -18<=k<=24 -24<=l<=16 -39<=h<=36 -37<=k<=37 -11<=l<=37 Reflections collected 46794 19464 27467 Unique Reflections 2681 776 5997 R(int) 0.1163 0.0658 0.0955 Goodness-of-fit on F2 0.963 1.101 S=1.01 Final R indices R1=0.1334, wR2=0.2845 R1=0.0501, wR2 = 0.1439 R1 = 0.0973, wR2 = 0.2266 Max. and Min. Resd. Dens., e -3 0.956 and -0.946 0.602 and -0.758 0.643 and -0.607

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83 Appendix II: Thermal Gr avimetric Analysis (ME658)

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84 Appendix II (continued) (ME500)

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85 Appendix III: UV-Visible Spectroscopy 300400500600700 0.0 0.2 0.4 0.6 0.8 absorbance (a.u.)wavelength (nm) sod-ZMOF Acridine Yellow-exchanged sod-ZMOF Acridine Orange-exchanged sod-ZMOF 9-(methylbromo)acridine-exchanged sod-ZMOF

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86 Appendix III (continued)