| The research of metal-organic coordination polymer is important for crystal engineering. Due to their overcoming framework and chemical stability in synthesis, coordination polymers have attracted much more attentions because of their various topologies and promising applications in hydrogen storage, optics, electrics, magnetism, catalysts and adsorption in recent years. Recently, much research effort has focused on the coordination polymers with novel topological structures which are constructed by suitable metal ions and versatile organic ligands through covalent bands and intermolecular interactions in accordance with the principle of the molecular engineering. Now, a great number of one-, two-, and three-dimensional coordination polymers have been successfully prepared.With the development of coordination chemistry, large amounts of coordination polymers with novel topological structures and properties have been synthesized. But, the synthesis process of coordination polymer is quite complicated and people cannot get a thorough understanding of the formation mechanism of coordination polymer,which need further research and more experimental data,finally to achieve the aims of molecular-design and directional synthesis.On the base of above discussed content, we report five coordination polymers synthesized by different rigid/flexible carboxylate ligands(H2oda, succinic acid, HIN, H2pdc) under homoeothermy /hydrothermal conditions and characterized by IR, TG analysis and fluorescence. The aim of this thesis is to design molecular directional synthesis by controlling the reaction conditions to obtain novel functional coordination polymers.In chapter one, a brief introduction of coordination polymer is involved including research methods, histories and new developments of the uranyl coordination polymers. At the end of this part, the goals and achievements of this thesis are summarized.Today, the extensive investigations of nuclear waste disposal bring considerable interests in crystal chemistry of uranyl polymers. In crystal structure of uranyl polymers, the approximately linear uranyl ion is coordinated by four, five or six anions in an equatorial planar arrangement. Uranyl polymer is connected by U-O polyhedron and inorganic oxygen acid radical would become multi-structural compounds.In chapter two, we chose flexible ligand-Diglycolic acid (H2oda) as a bridging ligand, CoCl2·6H2O and UO2(NO3)2·6H2O as reaction system at room temperature and atmospheric pressure, then obtained two coordination compounds: {[(UO2)(oda)2Co(H2O)4]·2H2O}(1),{(UO2)oda}(2). In compound 1, the U centers in the frameworks adopt eight-coordinate hexagonal bipyramidal geometry and Co centers adopt six-coordinate octahedral geometry, and both are bridged by oda ligands to generate one-dimensional chain structure. The chain packing (in the complex) gives rise to three-dimensional structure based on hydrogen bonding interactions. In compound 2, the U center in the frameworks adopts seven-coordinated pentagonal bipyramid, these polyhedra are connected by oda lignads to form an infinite three-dimensional framework with complicated topological structure. The compound 2 exhibits strong emission at room temperature. In chapter three, we employed isonicotinic acid, H2Pdc as rigid ligand under hydrothermal condition by changing the reaction temperature. We successfully prepared one supramolecular coordination polymer {Zn(H2O)4(IN)2}(3) and one 0-D{[Pr(HPdc)3]·(DMA)3}(4). In compound 3, each Zn coordinates with two isonicotinic acid molecules. The chain packing gives rise to three-dimensional structure based on hydrogen bonding interactions. Compound 4 has 0-D structure with [Pr(HPdc)3]·(DMA)3 molecule as a unit , in which each Pr coordinates to three H2pdc molecules.In chapter four, compound 5 {[(UO2)2(phen)2(C4H4)2]H2O} with flexible succinate acid and phen as a rigid ancillary ligands were synthesized under hydrothermal condition. Compound 5 is a 1-D chain framework in which the U centers (in the frameworks) adopt eight-coordinate hexagonal bipyramidal gemotries and the chain structure are connected by succinate acid ligands. The chain assembled into the 3-D supramolecular framework based onπ-πstaking interactions. The compound 5 exhibit strong emission at room temperature.
|
PDF Full Text Request