Synthesis, characterization and biological activities of homo-binuclear Cu(II) and Zn(II) complexes derived from 2-hydroxy-5-methyl-1,3-benzenedicarboxaldehyde derivatives

Abstract

Abstract Few novel binuclear Schiff base metal complexes [M2LCl3], where M = Cu(II) and Zn(II); L= 2,6-bis-({2-[(3-hydroxy-4-nitrobenzylidene)amino]ethylimino}methyl)-4-methylphenol (BHEM), 2,6-bis-({2-[(3,4-dimethoxybenzylidene)amino]ethylimino} methyl)-4-methylphenol (BDEM) and 2,6-bis-({2-[(2,3,5-trichlorobenzylidene)amino]ethylimino}methyl)-4-methylphenol (BTEM), have been synthesized and characterized by analytical and spectral data. The data suggest that BHEM/BDEM/BTEM ligands afford square-pyramidal/distorted square-pyramidal geometry on metalation with Zn(II)/Cu(II). The binding behaviour of these complexes with DNA has been investigated using electronic absorption spectroscopy as well as viscosity and voltammetric measurements; the results show that they interact with DNA through intercalating way. From the DNA cleavage study of these complexes, investigated by gel electrophoresis, we found that they efficiently cleave supercoiled pUC19 DNA in the presence of a reducing agent (3-mercaptopropionic acid) and on irradiation with UV light of 360 nm wavelength. The mechanism reveals that singlet oxygen (1O2) plays a significant role in the photo cleavage. The superoxide dismutase (SOD) mimetic activity of the synthesized complexes demonstrates that most of the complexes have promising SOD-mimetic activity. The antimicrobial study indicates that the complexes inhibit the growth of bacteria and fungi more than the free ligands.