Copper(II) Complexes with Tetradentate Piperazine-Based Ligands: DNA Cleavage and Cytotoxicity

Five-coordinate Cu(II) complexes, [Cu(Ln)X]ClO4/PF6, where Ln = piperazine ligands bearing two pyridyl arms and X ClO4? for L1 (1-ClO4), L2 (2-ClO4), L3 (3-ClO4), L6 (6-ClO4) as well [Cu(Ln)Cl]PF6 (1-Cl), L4 (4-Cl), L5 (5-Cl) have been synthesized characterized by spectroscopic techniques. The molecular structures of the last complexes were determined X-ray crystallography. In aqueous acetonitrile solutions, molar conductivity measurements UV-VIS spectrophotometric titrations revealed hydrolysis to [Cu(Ln)(H2O)]2+ species. biological activity with respect DNA cleavage cytotoxicity was investigated. At micromolar concentration within 2 h pH 7.4, rate decreased in order: 1-Cl ? 1-ClO4 > 3-ClO4 ? 2-ClO4 enhancements up 23 million. Complexes 4-Cl, 5-Cl, 6-ClO4 inactive. order elucidate mechanism, bis(4-nitrophenyl)phosphate (BNPP) reactive oxygen species (ROS) quenching studies conducted. mechanistic pathway depends on ligand’s skeleton: while an oxidative preferable 1-Cl/1-ClO4, predominantly proceeds via a hydrolytic mechanism. 1-ClO4, 3-ClO4, 5-Cl found be cytotoxic against A2780 cells (IC50 30–40 µM). fibroblasts, IC50 value much higher no toxic effect.