Synthesis, structure, luminescence and magnetic property of camphorate coordination polymers containing 5,6-dimethylbenzimidazole auxiliary ligand

Hydrothermal reactions of d-(+)-camphoric acid (d-H2cam) and 5,6-dimethylbenzimidazole (dmbi) with metal salts afforded three coordination polymers, namely [Cd2(d-cam)2(dmbi)4]n (1), [Zn2(d-cam)2(dmbi)2]n (2) and [Co(d-cam)1/2(l-cam)1/2(dmbi)]n (3), which were characterized by elemental analysis, IR, PXRD, CD, thermogravimetry and X-ray structural analysis. Complexes 1 and 2 are homochiral coordination polymers. 1 is a 1D left-handed helical chain coordination polymer constructed from tri- and tetra-dentate camphorate. 2 exhibits a 2D polymeric network assembled by tri-dentate camphorate, which belongs to 3-connected {4.82} topology. 3 is a 2D achiral coordination polymer assembled by left- and right-handed 1D Co-camphorate helical chains. It is rarely observed that d-cam ligand changes to l-cam under hydrothermal condition. Three complexes are all thermally stable up to 316–425 °C. 1 and 2 show violet luminescence originating from ligand-centered emission. 3 exhibits an antiferromagnetic interaction in CoII2 dimer with J = −4.34 cm−1.