Construction of cobalt-imidazole-based dicarboxylate complexes with topological diversity: From metal–organic square to one-dimensional coordination polymer

Two new complexes, namely, Co(IDC)(phen) (1) and [Co(PrIDC)(phen)]n⋅nH2O (2) (H3IDC = 4,5-imidazoledicarboxylic acid, H3PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, and phen = 1,10-phenanthroline) have been hydrothermally synthesized and structurally characterized. Complex 1 crystallizes in a tetranuclear fashion with a square ring-like structure. Complex 2 shows an infinite one-dimensional chain structure, in which the six-coordinated Co3+ exhibits distorted octahedral geometry. It is particularly worth noting that the existence of the substitute group of 2-position in the 4,5-imidazoledicarboxylate ligand plays a critical role in the formation of the resulting diverse topological structures. The fluorescence properties of complexes 1 and 2 in the solid state have also been investigated.