An Investigation on DNA Binding, Cleavage and Antimicrobial Properties of Mononuclear Co(II), Ni(II) and Cu(II) Complexes Derived from N, O Donor Schiff Bases.

Two sets of mononuclear N, O-chelate complexes, 1a [Co(L1)2(H2O)2], 1b [Ni(L1)2] and 1c [Cu(L1)2], and 2a [Co(L2)2(H2O)2], 2b [Ni(L2)2] and 2c [Cu(L2)2], from respective Schiff base ligands, HL1: 2-((E)-(6-(trifluoromethoxy)phenylimino)methyl)-5-methylphenol, C15H12F3NO2) and HL2: 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 complexes 1a and 2a, whereas square planar for complexes 1b, 1c, and 2b, 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 amyloliquefaciens and Escherichia coli as well as fungal species, Macrophomina phaseolina and Sclerotium rolfsii.