Four new Schiff bases have been derived from the condensation of acenapthoquinone and naphthylamines in 1:2 molar ratios. These Schiff base ligands were used to synthesise novel mononuclear Ni(II) complexes with square planar geometry. The ligands and the complexes have been investigated by elemental analyses, spectroscopic methods (FT-IR and UV-Vis.,), molar conductance and magnetic susceptibility studies. The electrochemical properties of Ni(II) complexes have been studied by cyclic voltammetry technique. The catalytic efficacy of the complexes has been analysed in the oxidation of toluene to benzyl alcohol, using H2O2. Biological activities of these ligands and complexes were checked against selected bacterial strains (E. coli and S. Aureus).

In this study, the authors report the synthesis of a new Mannich base formed by the condensation of pyrrole (C4H5N), 4-hydroxybenzaldehyde (C7H6O2) and phthalimide (C8H5NO2) and the respective copper (II) (Cu2+), nickel (II) (Ni2+) and cobalt (II) (Co2+) transition metal complexes derived from the ligand. The synthesized ligand and the metal complexes were characterized using elemental analysis, electrical conductivity studies and spectral studies. The geometry of the Mannich base metal (II) complexes was studied by ultraviolet–visible and electron spin resonance spectroscopy, and all the complexes were found to adopt square planar geometry. Among all the complexes, the cobalt complex was observed to show better antioxidant properties. It is noteworthy to mention that the copper complex is observed to exhibit better deoxyribonucleic acid cleavage activity at all concentrations compared with other complexes.