Syntheses, Characterizations And Properties Of Zinc Coordination Polymers Based On Rigid Ligands

Metal-organic coordination polymers with well-regulated network structures has received considerable attention, mostly motivated by their intriguing structures and potential applications in the fields of catalysis, gas absorption, nonlinear optics, ion-exchange, luminescence and so on. Although a number of coordination polymers with intriguing architectures and interesting properties have been reported, a rational strategy to synthesize desired solid-state materials is still one of the great challenges in synthesis chemistry. Considering the synthetical factors on such materials, such as metal ion, ligand, solvent, temperature and so on, we investigated the reactions between the rigid multi-carboxylate ligands /mixed-ligand and Zn (Ⅱ) ions to construct novel coordination polymers. The spherical d10 configuration is associated with a flexible coordination environment so that geometries of Zn complexes can vary from tetrahedral through trigonal bipyramidal and square pyramidal to octahedral and severe distortion of the ideal polyhedron easily occurs. Furthermore, due to the general lability of Zn complexes the formation of coordination bonds is reversible which enables metal ions and ligands to rearrange during the process of polymerization to give highly ordered network structures. Consequently, Zn can readily accommodate all kind of architectures. In many cases rather similar ligands lead to completely different coordination arrays.Two compounds were isolated by solvothermal technique and structurally characterized by elemental analyses, XRPD, IR, single crystal X-ray diffractions and TG.. The luminescent properties were also investigated for the compounds.Compound (H3O)2[Zn(BTEC)] (1) is a three-dimensional network containing one-dimensional rhombic channels with the sizes of the windows are approximately 8 ? at the widest and 4.5 ? at the narrowest spacing (excluding the van der Waals radius of atoms in the framework) running along the c axis. [Zn2 (BDC) (4, 4′-bipy) (HCOO) 2] (2) is a compound based on mix-liangd. It provides the first coordination polymer structure constructed together by bridging BDC, 4, 4′-bipy and formate ligands. Both the BDC and 4, 4′-bipy link up zinc atoms alternatively resulting in a zigzag coordination chain, and adjacent chains are further linked by formates to form an infinite extended two-dimensional folding screen layer. Remarkably, the formate which comes from DMF hydrolyzation acting as bi-dentate bridging ligand coordinates to zinc ions, which has rarely been observed.