Syntheses, crystal structures, and thermal properties of two complexes built by imidazole-based multi-carboxylate ligands

Based on two promising p-CPhH4IDC and o-CPhH4IDC ligands, one 2D coordination polymer, [Ca(p-CPhH2IDC)(H2O)] n (p-CPhH4IDC = 2-(4-carboxylphenyl)-1H-imidazole-4,5-dicarboxylic acid) (I) and one novel dimeric complex, [Cd2(o-CPhH2IDC)2(H2O)6] · 4H2O (o-CPhH4IDC = 2-(2-carboxylphenyl)-1H-imidazole-4,5-dicarboxylic acid) (II) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 929826 (I), 959841 (II)). Polymer I exhibits a graceful 2D grid sheet structure. Polymer II is a binuclear complex in which two Cd2+ ions are bridged by two carboxyates from two o-CPhH2IDC2– ligands. Four and two types of coordination environments around the Ca and Cd atoms, respectively can be observed. Furthermore, the solid-state photoluminescence and thermal properties of the two complexes have been investigated.