Synthesis, structure and photoluminescence of two cadmium coordination polymers with 1,3-benzenedicarboxylate and two flexible bis-imidazole ligands

Two new coordination polymers, [Cd2(2-mBIM)2(1,3-BDC)2]n (1) and [Cd(BIM)(1,3-BDC)]n (2) [BIM = bis(imidazol-1-yl)-methane, 2-mBIM = bis(2-methylimidazol-1-yl)methane], were synthesized by reactions of CdCl2 with 2-mBIM or BIM ligand in the presence of 1,3-benzenedicarboxylic acid. The polymers were then characterized by elemental analyses, IR, TGA, and X-ray diffraction. Compound 1 is a two-dimensional (2D) twofold parallel interpenetration network with a (4, 4) connected topology. Compound 2 is a 2D double-layer framework containing [Cd2(COO)4] subunits. The results of this study suggest that subtle changes in the ligand structure may have a great impact on the resulting architectures of the metal–organic frameworks. Solid-state luminescent spectra of compounds 1 and 2 indicate weak fluorescent emissions at ca. 389 and 302 nm, respectively.