An Investigation on DNA Binding, Cleavage and Antimicrobial Properties of Mononuclear Co(II), Ni(II) and Cu(II) Complexes Derived fromN,ODonor Schiff Bases

Two sets of mononuclearN, O-chelate complexes,1a[Co(L-1)(2)(H2O)(2)],1b[Ni(L-1)(2)] and1c[Cu(L-1)(2)], and2a[Co(L-2)(2)(H2O)(2)],2b[Ni(L-2)(2)] and2c[Cu(L-2)(2)], from respective Schiff base ligands,HL1: 2-((E)-(6-(trifluoromethoxy)phenylimino)methyl)-5-methylphenol, C15H12F3NO2) andHL(2): 2-((E)-(4-(trifluoromethoxy)phenylimino)methyl)-4,6-dichlorophenol, C14H8Cl2F3NO2) have been synthesized and well-characterized by analytical and various spectroscopic techniques like mass spectrometry, FT-IR, UV-visible, magnetic susceptibility, ESR and thermogravimetric studies. The geometries are proposed as octahedral for complexes1aand2a, whereas square planar for complexes1b,1c,and2b,2c. DNA binding study was investigated against calf thymus DNA for synthesized complexes comparing with parent ligands and resulted in intercalation mode of binding which was further supported by fluorescence quenching and viscometric titrations. Nuclease efficacy was also investigated against supercoiled pBR322 DNA and a good cleavage pattern was shown by metal complexes. The complexes were found to possess good antimicrobial activity compared to free ligands against bacterial species,Bacillus amyloliquefaciensandEscherichia colias well as fungal species,Macrophomina phaseolinaandSclerotium rolfsii.