Synthesis, Characterization, Antioxidant and Antimicrobial Studies of Acenaphthaquinone Based Schiff Base and Its Corresponding Co(II), Ni(II), Cu(II) and Zn(II) Metal Complexes

Abstract

A new series of transition metal ions viz. Co(II), Ni(II), Cu(II) and Zn(II) complexes in the 1:1, M:L ratio have been synthesized using 1,5-dimethyl-4-((2-oxoacenaphthylen-1(2H)-ylidene)amino)-2- phenyl-1,2-dihydro-3H-pyrazol-3-one, Schiff base as a ligand derived via condensation reaction between acenaphthaquinone and 4-aminoantipyrine in acetonitrile and characterized by elemental analysis, FTIR, UV-VIS, 1H NMR, 13C NMR, LC-MS, powder XRD, atomic absorption measurements and TGA-DSC. Based on magnetic and electronic data, it has been suggested that Co(II), Ni(II) and Cu(II) complexes have octahedral geometry, while zinc(II) complex has tetrahedral geometry. It has also been found that all these complexes except for [ZnLCl2] are paramagnetic. The molar conductance values indicated that Co(II) and Ni(II) complexes are electrolytic and Cu(II) and Zn(II) complexes are non-electrolytic, respectively. The thermal analysis data confirmed the suggested formula, the presence of coordinated and lattice water molecules and the stability of metal(II) complexes. From powder XRD analysis, the average crystallite size of all the compounds was observed within the nanoscale. The DPPH antioxidant studies revealed that the metal(II) complexes showed better antioxidant activities than the ligand. The metal(II) complexes were found to be effective antimicrobial when they were tested in vitro against six bacteria (S. aureus, B. subtilis, Corynebacterium, E. coli, P. vulgaris and S. enterica) and three fungi (A. oryzae, A. niger and C. albicans).