Syntheses And Properties Of Bis(benzimidazole)-based Transition Metal Camphorate Coordination Polymers

In this paper, a series of bis(benzimidazole)-based transition metal camphorate coordination polymers [M(D-cam)(bbbm)][M(L-cam)(bbbm)] [M = Co(1), Ni(2) and Zn(3)], [CuII(OH)(bbbm)(H2O)]2(NO3)2·2H2O(4), [CuI(bbbm)2](HCOO)(5), Cd4(D-cam)4(bbbm)2(6) and [Co(bbmmb)(L-cam)]·H2O(7) have been hydrothermally synthesized by using D-camphoric acid(D-H2cam) as main ligand, flexible 1,1’-(1,4-butanediyl)bis-1H-benzimidazole(bbbm) and semi-rigid 4,4’-bis(benzimidazol-1-ylmethyl)biphenyl(bbmmb) as co-ligands and transition metal as central ions.X-ray single-crystal diffraction anylasis reveals that polymers 1–3 are isostructural and possess three-dimensional(3D) supramolecular architectures based on two types of homochiral layers. Polymers 4 and 5 are two-dimensional(2D)(4,4) layers. Polymer 6 is a 3D homochiral framework containing two types of dinuclear cadmium clusters. Polymer 7 shows a 2D homochiral layer structure. The structural studies indicate that the flexibility of bis(benzimidazole)-based ligands, D-camphoric acid and transition metal ions have a great influence on the final structures of polymers 1–7.The thermal analysis exhibits that polymers 1–7 possess high thermal stability. The solid state fluorescent measurement indicates that polymers 1–7 display the luminescence of bis(benzimidazole)-based ligands. The variable-temperature magnetic susceptibility measurement shows that an antiferromagnetic interaction exists within the dinuclear copper cluster of polymer 4.