Syntheses,Structures And Characterization Of Coordination Polymers Based On Mixed-ligands

Coordination polymers(CPs), especially Co(II)-CPs have attracted growing attention from researchers, not only owing to their excellent physical and chemical properties but also owing to their potential applications in many fields. The final structures and properties of Co(II)-CPs are determined in a large measure by the organic ligands. Therefore, the rational selection of organic ligands is vital to the self-assembly process of Co(II)-CPs. Substituted bis(benzimidazole) ligands have been successfully designed and synthesized. Using these ligands and aromatic dicarboxylates as mixed ligands, twelve novel Co(II)-CPs based on substituted bis(benzimidazole) ligands and aromatic dicarboxylates have been hydrothermally synthesized. The crystal stuctures of these complexes have been characterized by elemental analysis, IR spectra, X-ray powder diffraction and single-crystal Xray diffraction. The thermogravimetric analysis, fluorescence and catalytic activities were investigated. Moreover, the influences of flexiblility, substituted group of different position and carboxylate ligands on the final structures of these complexes have been discussed in detail.1) The combination of four substituted benzimidazole ligands L1~L4 with three kinds of benzenedicarboxylates ligands as mixed-ligands construct six Co(II)-CPs with interesting structures. Complex 1 shows a 3D two-fold interpenetrating dia network, complex 2 displays the first example of 3D 3,3,5L18 framework, complexes 3 and 6 both exhibit 2D(4,4) network, complex 4 represents a 1D ladder-like chain, complex 5 is a two dimentional 3,4L15 topology structure.2) Six Co(II)-CPs based on 2,6-naphthalenedicarboxylic acid and various substituted bis(benzimidazole) ligands have been synthesized under hydrothermal conditions. Complexes 7, 10 and 11 possess 2D(4,4) network, which are further arranged into high dimensional architectures via hydrogen bonds interactions. Complex 8 features a three dimensional three-fold interpenetrating framework with xah topology. Complexes 9 and 12 show 1D infinite chain, which are further extended into three dimentional supramelcular networks by hydrogen bond interactions.Systematically structural comparison of these polymers reveals that bis(benzimidazole) ligands and aromatic carboxylate ligands play important roles in the self-assembly process. All complexes display high thermal stabilities and different fluorescence properties. Complexes 1, 4, 5, 8, 9 and 12 exhibit higher catalytic activities of degradation azo dye in Fenton-like process, implying those potential application in catalytic materials.