Structure, Characterization and Photocatalytic Activity of a Series of Well-Established Covalent Heterojunction Coordination Polymers

Abstract

Six novel coordination polymers {Co(HCOO)2(4,4′-bipy)}n (1), {[Ni(4,4′-bipy)(OH)2(H2O)2]·suc·2H2O}n (2), {Ni(HCOO)2(4,4′-bipy)}n (3), {Zn(HCOO)2(4,4′-bipy)}n (4), {Cu(HCOO)2(4,4′-bipy)}n (5) and {[Cu(ox)(2,2′-bipy)]·2H2O}n (6) (suc succinic acid, ox oxalic cid) based on pyridine derivatives and carboxylates as ligands were designed and synthesized. The coordination polymers were characterized by elemental analysis, IR and UV–Vis spectra, powder X-ray diffraction, the thermo gravimetric analyses and single-crystal diffraction analysis. The structure analysis showed that the central metal atoms in coordination polymers 1, 2, 3, 4 and 6 all were six-coordination modes, forming distorted octahedron geometries. Cu atom in the coordination polymer 5 was four-coordination mode, forming square planar coordination geometry. While in the coordination polymers 1, 3 and 4, two metal centers were connected by bridging coordination fashions of formic acid ligand, forming a three-dimensional network structure, and in the coordination polymer 6, the two metal centers were connected by bridging coordination fashions of oxalic acid ligand, forming one-dimensional chain. In addition, the photocatalytic activity of a series of covalent heterojunction coordination polymers was studied.