Three metal–organic frameworks constructed from imidazole-based multi-carboxylate ligands: Syntheses, structures and photoluminescent properties

Three metal–organic frameworks, [Ba(o-CPhH2IDC)]n (1), {[Ca(o-CPhH2IDC)(H2O)2]·H2O}n (2), (o-CPhH4IDC = 2-(2-carboxylphenyl)-1H-imidazole-4,5-dicarboxylic acid) and {[Cd(m-CPhH2IDC)(phen)]·H2O}n (3) (m-CPhH4IDC = 2-(3-carboxylphenyl)-1H-imidazole-4,5-dicarboxylic acid and phen = 1,10-phenanthroline), have been solvothermally synthesized and structurally characterized by elemental analyses, IR, thermogravimetric analyses and single-crystal X-ray diffraction. Compound 1 is a (5,5)-connected 3D structure. Compound 2 displays an infinite 1D double-chain structure. Complex 3 presents a wave-like architecture by π–π interactions from neighboring zig zag chains. The imidazole-based multi-carboxylate ligand demonstrates a strong coordination ability and versatile coordination modes. Furthermore, the thermal and solid-state photoluminescent properties have also been investigated.