Syntheses, Structures And Properties Of Coordination Polymers With Aromatic Carboxylates

In recent years,many coordination polymers or metal-organic frameworks have been synthesiszed,providing a variety of properties such as storage,exchange, catalysis,magnetic and optical properties.The organic ligands containing two or more carboxylate groups offer great potentials for fine control over coordination architectures.Under the guidance of crystal engineering,rigid aromatic phenylenediacrylic acid or phenylenetriacrylic acid are used as bridging ligands between metal ions,in combination with the use of chelate/pyridyl reagents as terminal ligands or bridging ligands.Twenty-six new coordination polymers, including one dimensional,two dimensional,and three dimensional motifs,have been prepared,and the magnetic and thermostability of some of the complexes have been characterized.This dissertation covers the following five parts:（1） Magnetic study of the coordination polymers based on different phenylenediacrylic acids:（ⅰ） We have revealed five layered compounds synthesized by the reaction of p-phenylenediacrylate or m-phenylenediacrylate acid（H₂ppda or H₂mpda） and transitional metal ions of Mn（Ⅱ）,Fe（Ⅱ） and Co（Ⅱ）. In all these compounds,the 2D rhombic layers feature single carboxylate bridges in the syn-anti mode and relatively inclined metal polyhedrons alternating along the bridges.Variable-temperature magnetic susceptibility measurements indicate the presence of antiferromagnetic in the M（Ⅱ）-carboxylate sheet,while compounds 1 and 2 exhibit spin-canted antiferromagnetism,with weak ferromagnetic transition at 3.8 K and 4k respectively.It is worth to note that compound 2 represents the first Fe（Ⅱ） compound containing the single-carboxylate bridged layers.（ⅱ） A novel 3D lanthanide coordination polymer with an unprecedented 3,7-connected topology （4,6²）₂（4²,6）(4⁷,6⁴,8¹⁰)was synthesized by a solvothermal technique from Nd（Ⅲ） ion and H₂mpda and structurally characterized.The magnetic properties is typical of the Nd（Ⅲ） ⁴I_9/2 ground state perturbed by the ligand field and probable antiferromagnetic exchange through tripleμ₂-oxygen bridges.（2） Syntheses,structures,and properties of Zinc（Ⅱ） and Cadmium（Ⅱ） coordination polymers with different phenylenediacrylic acids:Self-assembly of different ligands of H₂ppda and H₂mpda with Zn（Ⅱ） and Cd（Ⅱ） under different reaction conditions yielded six novle complexes varying from zero- to three-dimensions, showing that the reaction conditions and the configuration of ligands play crucial roles in controlling the topological structures of the supramolecular architectures.（3） Different phenylenediacrylic acids coordination polymers tuned by chelate terminal ligands:Six phenylenediacrylic acids metal-organic coordination polymers decorated chelating terminal ligands have been synthesized.X-ray analysis revealed that the structures consist of infinite 1D polymeric chains or 2D layers,and the packing modes of the frameworks were investigated.The framework stability and magnetic properties of some of the polymers also have been characterized.（4） Crystal engineering of coordination polymers with phenylenediacrylic acids and different bipyridyl bridging motifs:A series of novel 2D and 3D coordination compounds with entangled structures have been synthesized under hydrothermal conditions or diffusion method and structurally characterized by single crystal X-ray diffraction.The framework stability of some of the polymers has been investigated.（5） Syntheses and X-ray structures of manganese and cadmium coordination polymers based on new phenylenetriacrylic acid:The secondary building unit （SBU） has been identified as a useful tool in the constrution of metal-organic frameworks.We illustrate two new 3D coordination polymers based on the solvothermal reactions of H₃BTA with Mn（Ⅱ） or Cd（Ⅱ）.Syntheses,crystal structures,and structure analysis using the polymeric SBU approach are presented for each compound.The framework stability and magnetic properties of some of the polymers have been investigated.