Cytotoxic copper (II) mixed ligand complexes: crystal structure and DNA cleavage activity.

Two new mixed ligand complexes of copper (II) containing an imidazolyl terpyridine ligand, [Cu(Itpy)(bpy)](ClO(4))(2)·(H(2)O), 1, and [Cu(Itpy)(phen) (ClO(4))](ClO(4))·(H(2)O), 2 have been synthesized and characterized. Complex 1 has been found to possess a distorted square pyramidal geometry whereas 2 exhibit a distorted octahedral geometry. Electronic spectral titrations suggest that 1 and 2 bind to DNA intercalatively with the binding constant, K(b) (4.12 ± 0.13) × 10(4) M(-1) (1) and (6.04 ± 0.15) × 10(4) M(-1) (2). Under physiological condition, in the absence of any external cofactor 2 has been found to bring about DNA cleavage via hydrolytic mechanism but 1 does not bring about any DNA cleavage. Both compounds show antitumor effects on the A549 lung adenocarcinoma cancer cell line.