| The research of metal-organic coordination polymer remains an extremely active field of materials chemistry in recent years. According to the principle of the crystal engineering, it is possible to control the structure of the coordination polymer at a certain extent. At the same time, coordination polymer can be endowed with some properties, such as catalysts, adsorption, nonlinear optical activity, electrics and magnetism. As the properties of the coordination polymers is determined by their chemical constituents and framework topologies, seeking the coordination polymers with the novel topology has been considered as the exploiting the functional properties of the coordination polymers. Latest years, many research groups at home and abroad get a lot of great fruits in design, synthesis and functional development according to the principle of the crystal engineering. However, the synthesis mechanism is still not known due to the terrible complexity of the synthesis-chemistry in coordination polymer. So it is need to deeply research and accumulates abundant experimental facts, finally to achieve the aims of molecular design and directional synthesis. A useful way of producing supramolecular structures is based on complementarity and selectivity of the ligands, which are crucial for coordination polymers using noncovalent interactions such as hydrogen bonding,π···π, C–A···π, cation···π, anion···π, etc. The small molecules reveal noncovalent interactions as major forces that stabilize supramolecular structures. So far, the bridging ligands containing O- or N- donors through either covalent bonds or weaker intermolecular interactions are used to bind metal centers, generating a number of one- two- and threedimensional infinite frameworks.We synthesized some coordination polymers after rationally designing the bridging ligands and metals according to the principle of the crystal engineering. In the mean time, we studied the mainly factors on the synthesis of coordination polymers via changing the metal ions to adjust the inorganic components or ligands to adjust the framework components. On the base of large tests, we synthesized some coordination polymers with novel structures using different ligands, and summarized the rules of synthesis. Influences of other experimental factors, such as reaction temperatures, reaction times, pH values and molar ratios of the starting materials etc on the composition, the structures, purity and crystallinity of the final products were studied.In chapter two, a series of coordination polymers with novel structure using the 1, 2, 4-triazole ligands, [Zn2(C2H2N3)3Cl] (1), [Cd3(C2H2N3)4Cl2]·0.25H2O (2), [Zn2(C2H2N3)2(C2O4)] (3), [Zn(C2H2N3)(CH3COO)] (4), [Zn3(C2H2N3)2(C7H5O2)4] (5), [Zn(C2H2N3)(C8O4H5)] (6), [Zn4(C2H2N3)4(C7H4O2F)4]·0.5H2O (7) and [Zn4(C2H2N3)4(C7H4O2Cl)4] (8) have been synthesized under mild conditions. Compound 1 consists of [ZnN3Cl] tetrahedron and [ZnN6] octahedron, which are connected by 1, 2, 4-triazole to form a 3D framework. Compound 2 consists of [CdN4Cl] trigonal bipyramid and [CdN4Cl2] octahedron, which are connected by 1, 2, 4-triazole and Cl atoms to form a 3D framework. Compound 3 consists of [ZnN3O] tetrahedron and [ZnN2O4] octahedron, which are connected by 1, 2, 4-triazole and oxalic acid ligands to form a 3D framework. Compound 4 consists of [ZnN2O2] tetrahedron and [ZnN2O4] octahedron, which are connected by 1, 2, 4-triazole and acetic acid ligands to form a 3D framework with nonlinear optical properties. Compound 5 consists of [ZnN2O2] tetrahedron and [ZnN2O4] octahedron, which are connected by 1, 2, 4-triazole and benzoic acid ligands to form a 3D framework with helical units. Compounds 6-8 have the same 2D layer constructed by zinc (II) with trz and carboxylate. The main difference in the structure of the three compounds is crossbedded arrangement between the layers. In order to understand the causes of this phenomenon, we studied the noncovalent intermolecular interactions in the compounds. Compound 6 shows unusual intermolecular hydrogen bonding and C–O···πinteractions, compound 7 exhibits intermolecular hydrogen bonding and C–F···πinteractions, while compound 8 only shows intermolecular C–Cl···πinteractions. It is found that the noncovalent intermolecular interactions have an influence on crystal packing. We performed the binding energy calculations at the MP2 level of theory with the 6-31++G** basis set, for the interaction of 1, 2, 4-triazole with the oxygen, fluorin and chlorin atoms. It is easy to draw the conclusion that the intermolecular interactions are induced by C–(O, F or Cl)···πinteractions.In chapter three, a series of coordination polymers using the squaric acid ligand, [Fe(C4O4)(H2O)2] (9), [Ni(C4O4)(H2O)2] (10), [Co3(C4O4)3(H2O)6] (11) and [Zn(C4O4)(1,10-phen)(H2O)2] (12) have been synthesized under mild conditions. Compounds 9-11 exhibit similar sodalite structure with the 4-membered square of the squarate acids acts as the basic building unit, and there are strong hydrogen bonds interactions in structures; Compound 12 is a [Zn(C4O4)(1,10-phen)(H2O)2]∞1-D chains through squaric acid anions bridging the [Zn(1,10-phen)(H2O)2] units, and there are strong hydrogen bonds andπ···πinteractions. Furthermore, a series of coordination polymers using the acetylenedicarboxylic acid ligand, [Zn(C4O4)(2,2'-bipy)]·(H2O)2 (13), [Cd(C4O4)(2,2'-bipy)(H2O)]·(H2O) (14) and [Mn(4,4'-bipy)(H2O)4]·(C4O4)·4H2O (15) have been synthesized under mild conditions. Compound 13 exhibits one dimensional chain structure which is repeated by the -[Zn(2,2'-bipy)(H2O)2]-C4O4- unit, and is extended to two dimensional layer structure by interaction of hydrogen bonds between chains; Compound 14 exhibits two dimensional layer structure which is linked by [Cd(2,2'-bipy)(H2O)]2+ and [C4O4]2- units; Compound 15 is a 3-D supramolecular structure with acetylenedicarboxylic acid anions bridging the [Mn(4,4'-bipy)(H2O)4]2+∞anions through hydrogen bonds interactions. |
PDF Full Text Request