Synthesis and crystal structure of new monometallic and bimetallic copper(II) complexes with N-substituted isatin thiosemicarbazone ligands: Effects of the complexes on DNA/protein-binding property, DNA cleavage study and in vitro anticancer activity

A novel series of N-substituted isatin thiosemicarbazone ligands (L1-L3) and their copper(II) complexes [Cu(II)(ITSC)] were synthesized and characterized by elemental analyses and UV-Vis, H-1 & C-13 NMR/EPR and mass spectroscopic techniques. The molecular structures of L1, L2, L3, 2 and 3 were confirmed by single crystal X-ray crystallography. The X-ray diffraction studies of the complexes 2 and 3 reveal the square planar and square pyramidal geometry. The binding affinity and binding mode of the monometallic and bimetallic complex toward calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were determined by UV-Vis and fluorescence spectrophotometric methods. Spectral evidences show intercalative mode of DNA binding with the copper(II) complexes. Complexes (1, 2 and 3) cleaved the pUC19 plasmid DNA in the absence of an external agent. An in vitro cytotoxicity study of the complex 3 found good activity against human breast (MCF7) and lung (A549) cancer cell lines. (C) 2016 Elsevier Ltd. All rights reserved.