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)](ClO4)(2)center dot(H2O), 1, and [Cu(Itpy)(phen) (ClO4)](ClO4)center dot(H2O), 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 inter-calatively with the binding constant, K-b (4.12 +/- 0.13) x 10(4) M-1 (1) and (6.04 +/- 0.15) x 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. (C) 2011 Elsevier Masson SAS. All rights reserved.