Synthesis, characterization and DNA-binding studies of mono and heterobimetallic complexes CuSn2/ZnSn2 and their DNA cleavage activity

Heterobimetallic complexes C6H24N4O6CuSn2Cl6 3, C6H24N4O6ZnSn2Cl6 4 have been synthesized from their monometallic analogs C6H16N4O2CuCl2 1, C6H16N4O2ZnCl2 2, and were characterized by various spectroscopic and analytical methods. The complexes 1–4 reveal an octahedral geometry for both central metal ions Cu/Zn as well as for Sn metal ion. The interaction of complexes 1–4 with CT-DNA, were investigated by using absorption, emission, cyclic voltammetry, viscometry and DNA cleavage studies. The emission quenching of 3 and 4 by [Fe(CN)6]4− depressed greatly when bound to CT-DNA. The results of spectroscopic, viscometric and cyclic voltammetry of complexes 3 and 4 revealed electrostatic mode of binding of the complexes with CT-DNA. These results revealed that 4 bind more avidly in comparison to 3 with CT-DNA. Gel electrophoresis of DNA with complexes 3 and 4 demonstrated that the complexes exhibit excellent cleavage activity under physiological conditions.