Spectroscopic evidence of Cu(II) and Zn(II) complexes having amino acid based Schiff base: A special emphasis on in vitro antimicrobial, DNA binding and cleavage studies

A new Schiff base ligand (L) obtained by the condensation reaction of N-acetylaceto-otoluidine and 2-aminopropanoic acid (an amino acid), is used to synthesize four mononuclear complexes of [MLCl] and [ML2] types (where M = Cu(II) and Zn(II); L = Schiff base) by keeping the metal and ligand ratio as 1:1 and 1:2 respectively. This ligand and its complexes have been characterized on the basis of different spectral methods. EPR, UV-Vis. and magnetic moment data afford a square-planar geometry for the [MLCl] complexes and octahedral geometry for the [ML2] complexes. The observed low molar conductivity of these complexes at room temperature is consistent with their non-electrolytic nature. All the complexes display significant oxidative cleavage of circular plasmid pBR322 DNA in the presence of hydrogen peroxide. UV spectroscopic titration with CT DNA reveals that the complexes can bind to CT DNA and the binding constants to CT DNA have been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA reveal that they bind to CT DNA probably by the intercalative binding mode. The antimicrobial activity of the complexes has been tested against microorganisms showing that they exhibit higher activity than free Schiff base ligand.