[Synthesis, structure and special study of 1D cadmium sulfate-H2biim coordination polymer]

A novel cadmium complexes of {[Cd(H2 biim)2 (SO4)] x 3H2O}n(1) (H2 biim = 2,2'-biimidazole) was synthesized by hydrothermal reaction of 3CdSO4 x 8H2O and 2,2'-biimidazole ligand. The complex was built up by [Cd(H2 biim)2]2+ units bridged sequentially by SO4(2-) anions to form 1D zigzag chains parallel to the c-axis. The H2biim ligands were attached to the 1D chain as branches of the chain by coordinating to Cd2+ at two sides of the chain. The chains were held together by pi--pi interaction and O--H***O interactions, thus yielding a 3D extended supramolecular network The responses of symmetric stretching vibration of SO4(2-), N--C single bond, N==C double bond and anti-symmetric stretching vibration of N-C single bond were detected in 2D IR correlation spectra under thermal perturbation. The complex exhibited strong blue emission peak at 498 nm (lambda(ex) x = 397 nm) that can be assigned to a ligand-to-metal charge-transfer (LMCT) band.