An unexpected mixed valence tetranuclear copper(I/II) complex: Synthesis, structural characterization, DNA/protein binding, antioxidant and anticancer properties

Direct reaction of a hydrazone ligand with CuCl2(PPh3)(2) in methanol/acetonitrile 1:1 molar ratio resulted in the formation of an unpredicted tetra nuclear complex with mixed valence Cu(I)/(II) oxidation state. The new complex was characterized by various spectroscopic (IR, UV-Vis and NMR) techniques and the structure of the complex was confirmed by X-ray crystallography. Theoretical calculations (DFT) have been carried out for the complex. The interaction of the ligand and complex with calf thymus (CT-DNA) has been examined by photophysical studies, which revealed that the complex bound to DNA through intercalative mode. Albumin (Bovine Serum Albumin) binding studies of the ligand and complex confirmed their effect on altering the secondary structure by quenching the tryptophan and tyrosine residues. Antioxidant studies showed that the complex exhibited significant antioxidant activity. The anticancer activity of the ligand and complex was probed in vitro against human breast (MCF7) and lung (A549) cancer cell lines by MTT assay and cytological changes were observed in AO/EB and DAPI staining method. (C) 2019 Elsevier Ltd. All rights reserved.