SYNTHESIS, CHARACTERIZATION, AND IN VITRO ANTIMICROBIAL STUDIES ON NICKEL (II) AND COPPER (II) COMPLEXES OF SCHIFF BASE DERIVED FROM ISATIN (1H-INDOLE-2,3-DIONE) ANDS THIOSEMICARBAZONE

Abstract

The Schiff base ligand was obtained from the condensation of Isatin and Thiosemicarbazide.Its Nickel(II) and Copper(II) complexes were synthesized by the solutions of the ligand and that of the chloride of the correspond metal in the ratio of 2:1.The complexes obtained were characterized by FTIR, melting point/decomposition temperature determination, atomic absorption spectroscopy (AAS), magnetic susceptibility, and molar conductance and solubility tests.The complexes showed moderate values of decomposition temperatures.Infrared spectral data of the ligand and the complexes indicated coordination of the ligand to the metal (II) ion via azomethine nitrogen, indole oxygen and thionine sulphur; thus acting as a tridentate ligand.The complexes showed an effective magnetic moments of 3.34 BM and 0.94 BM for the NI(II) and Cu(II) respectively which suggests an octahedral geometry.The molar conductivities of 17.1 Ω -1 cm 2 mol -1 for the Ni(II) and 9.1 Ω - 1 cm 2 mol -1 for Cu(II) complexes indicated that these complexes are non-electrolytic.The results of the AAS and the empirical formula indicated that, the Schiff base is monobasic and tridentate towards the metal ions.The ligand and the complexes were tested for antimicrobial activity against Staphylococcus aureus, Salmonella typhimurium, Escherichia coli (bacteria); Aspergillus flavus, Aspergillus fumigatus and Mucor species (fungi).Amoxicillin and Ketoconazole were used as positive control for the bacteria and fungi isolates respectively.The results showed that the complexes are more active than the free ligand but not as active as the standard drugs.