Mononuclear Co(II), Ni(II) and Cu(II) complexes of the Schiff base, 2-(((4-trifluoromethoxy)phenylimino)methyl)-6-tert-butylphenol: Synthesis, spectroscopic characterization, X-ray study and biological evaluation

Abstract Three mononuclear binary complexes, 1 [Co(L)2(H2O)2], 2 [Ni(L)2] and 3 [Cu(L)2] with Schiff base ligand, HL 2-((E)-(4-trifluoromethoxy)phenylimino)methyl)-6-tert-butylphenol, C18H18F3NO2) were synthesized and characterized by elemental analysis, ESI mass, FT-IR, ESR, UV–visible, magnetic susceptibility, thermogravimetry and single crystal X-ray diffraction studies. The complex 1 adopted an octahedral geometry, whereas complex 2 owned a square planar geometry. The XRD analysis of the complex 3 confirmed a distorted square planar geometry around Cu(II) ion. DNA binding and cleavage studies of all complexes have been investigated against calf thymus (CT-DNA) and supercoiled pBR322 DNA, respectively. The complexes bound effectively to CT-DNA through an intercalation mode and also cleaved pBR322 DNA in an efficient manner. The complexes along with free ligand have been screened for antimicrobial activity against bacterial species, Bacillus amyloliquefaciens and Escherichia coli as well as fungal species Macrophomina phaseolina and Sclerotium rolfsii, and it is found that all complexes are more potent than ligand.