Complexes of Cobalt and Nickel Derived from Sulfonamide Derivative: Synthesis, Characterization and Antibacterial Activity

Sulfonamide moieties are well known antibacterial agents and commonly known as sulfa drugs. Herein, we have synthesized 2-(Sulfamoyl)-N-benzylbenzamide ligand by reacting saccharin and benzyl amine in refluxing xylene. The synthesized compound was further reacted with cobalt and nickel acetate in mild basic conditions at pH 8-9 to isolate purple and light green coloured metal complexes. The ligands and their corresponding complexes have been investigated by characterized different techniques such as UV-Vis., FT-IR, 1H NMR and 13C NMR analysis. The obtained results confirm the synthesis of the complexes as well as ligands. The disappearance of SO2-NH2 asymmetric signal in metal complexes and appearance of a single peak at 3245 cm-1 indicated the coordination of the nitrogen atom with the metal center. It was also confirmed from 1H NMR that NH2 protons resonated at 8.04 ppm and this signal was found absent after complex formation. The non-electrolytic nature of the metal complexes was confirmed by smaller value (0.45-0.71 μS/cm) of conductance measurements. The antimicrobial screening was carried out against Chromohalobacter israelensis, Chromohalobacter salexigens, Halomonas halophila, and Halomonas salina bacterial strains and the results reveal that the complexes are more potent anti-bacterial agents than the ligand. The nickel complex 5, was found more active against C. israelensis and H. salina with zone of inhibition 17.32 mm and 18.67 mm, respectively.