Synthesis, molecular structure and BSA-binding properties of a new binuclear Cd(II) complex based on 2-(1H-tetrazol-1-methyl)-1H-imidazole-4,5-dicarboxylic acid

Abstract

Abstract A new binuclear Cd(II) complex, [Cd2(H2tmidc)4(H2O)2]·6H2O (1) based on 2-(1H-tetrazol-1-methyl)-1H-imidazole-4,5-dicarboxylic acid (H3tmidc) has been synthesized and structurally characterized. The single-crystal X-ray diffraction analysis has revealed that there are two crystallographically distinct H2tmidc– anions in complex 1, one of which is coordinated to Cd(II) ion in a terminal fashion, while the other acts as a bis-connector linking two Cd(II) cations to form the dinuclear structure. The dimeric units are stabilized by intra-molecular O–H···O hydrogen bonds and π-π stacking interactions and are further connected into a three-dimensional supramolecular architecture through inter-molecular hydrogen bonds and π-π stacking interactions. The interactions of complex 1 with bovine serum albumin (BSA) were analyzed by fluorescence measurements under physiological conditions. The results have indicated that the fluorescence intensity of BSA was decreased considerably upon the addition of complex 1 through a static quenching mechanism. The synchronous fluorescence spectrum suggested that the interaction of complex 1 with BSA affects the conformations of tryptophan and tyrosine residues and thereby has an influence on the conformation of BSA.