Assembly, Structures And Properties Of Coordination Polymers Constructed From Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) And Zn(Ⅱ) With Aromatic Carboxylic Acids

In this research, 16 coordination polymers have been designed and synthesized with Co(II), Ni(II), Cu(Il), Zn(II) ions and aromatic carboxylate anions (benzoate, phthalate, isophthalate, terephthalate, pyromellitate, tetrachlorophthalate, 2-hydroxyisophthalate) by means of solution, hydrothermal or solvothermal reactions. The structures and properties of the coordination polymers have also been characterized.1. Two inorganic-organic hybrid materials, [Zn₈(SiO₄)(C₈H₄O₄)₆]_n (C₈H₄O+4 = isophthalate or terephthalate), have been assembled for the first time from the new type metal center Zn₈(Si0₄) and benzene dicarboxylate links. The robust square-grid-diamondoid or two-fold cuboid framework structures are exceptionally stable. The two materials exhibit intense photoluminescence upon photoexcitation. With this work as the starting point, a new family of hybrid materials with novel structures and properties can be designed and synthesized.2. Six coordination polymers with different network topologies have been constructed from zinc with terephthalate, benzoate or pyromellitate in organic solution or under hydrothermal synthesis conditions. In the structures of these complexes, zinc can act as the vertex of the networks in various styles: single atom; dicarboxylate, tricarboxylate or tetracarboxylate bridged binuclear SBU (secondary building unit); and octacarboxylate bridged trinuclear SBU. It can be concluded that zinc is a good candidate for the assembly of coordination polymers with carboxylate ligands.3. Six coordination polymers consisting of Co(II), Ni(II), Cu(II) and aromatic carboxylates have been synthesized under hydrothermal conditions. Co(II) ions form hydroxyl bridged trinuclear units and furthermore form an infinite 2D network by sharing corners of the trinuclear units. Nickel ion will not easily lose its coordinate water molecules when reacting with carboxylates, especially in the absence of nitrogen donor ligands. Nickel ion has a tendency to form mononuclear units. Copper ion is liable to form tetracarboxylate-bridged binuclear units and very likely to aggregate into polynuclear unit under hydrothermal conditions.4. Two coordination polymers composed of in situ synthesized ligand deriving from isophthaiic acid through the hydroxylation on the 2-position have been synthesized underhydrothermal conditions. By adjusting the synthesis conditions, including temperature, pH value of the mixture solution and reaction time, the degree of the hydroxylation of isophthalic acid can be relatively controlled and the product of different structures can be obtained. The reaction opens a promising new route for constructing novel coordination polymers.5. The effects of synthetic conditions on the structures of the coordination polymers have been studied. Synthesis under higher temperature or in organic solvents is favorable for metal ions to lose their coordinate water molecules and gather to form polynuclear metal centers and also for aromatic carboxylate ligands to connect more metal ions. As a result, robust 3D networks can be formed.