Synthesis, Characterizations and Luminescent Properties of Two Cadmium(II) Coordination Polymers Derived from Bis(Benzimidazole)-Based Ligands

Two Cd(II) coordination polymers, namely, {[Cd(L1)(chdc)]center dot(CH3CN)center dot(H2O)(2)}(n) (1) and [Cd(L-2)Cl-2](n) (2) (L1 = 1,4-bis(5,6-dimethylbenzimidazole-1-ylmethyl)benzene, L2 = 1,2-bis(5,6-dimethylbenzimidazole-1-ylmethyl)benzene, H(2)chdc = 1,4-cyclohexanedicarboxylic acid) have been obtained by hydrothermal methods and characterized by IR, TG, elemental analysis, XPRD and single crystal structure analysis. The Cd(II) atom has a distorted octahedral coordination geometry in 1 and a roughly square-pyramidal coordination geometry in 2. Polymer 1 possesses a two-dimensional (2D) flat (6,3) network constructed with L1 and chdc bridging ligands. Polymer 2 displays a one-dimensional (1D) loop-like chain structure bridged by chlorine anions and L2 ligand, which is further arranged into a 2D supramolecular layer through face-to-face pi-pi stacking interactions. The luminescent properties of the polymers 1 and 2 were investigated in the solid-state. Two new coordination polymers of cadmium have been synthesized by different bis(benzimidazole) ligands. Both the complexes are characterized by X-ray single crystal structure, thermal and photoluminescence study.