SYNTHESIS, SPECTROSCOPIC INVESTIGATION AND BIOEFFICACY OF SOME NOVEL SCHIFF BASE METAL (II) COMPLEXES

Two monobasic bidentate ligands  L¹H [2-(5-Bromo-2-dihydro-2-oxo-1H-indol-3-ylidene)hydrazine-carboxamide] and L²H [2-(5-Bromo-2-dihydro-2-oxo-1H-indol-3-ylidene)hydrazinecarbothioamide] were synthesized by the condensation of  [2-(5-Bromo-2-dihydro-2-oxo-1H-indol-3-ylidene)  with semicarbazide and thiosemcarbazide, which formed a series of complexes with cobalt(II) and nickel(II). The ligands and the metal complexes were characterized based on elemental analysis, IR, UV–Visible, ¹HNMR, Mass spectroscopy. Spectral studies revealed that the ligands acted as monobasic bidentate, coordinating to the metal ion through the azomethine nitrogen i.e. >C=N and carbonyl oxygen atom of the isatin moiety. All the Schiff base metal complexes have a mononuclear structure, and the octahedral geometry has been proposed on the basis of spectral studies. The nickel (II) complex Ni (L²) (OAc).3H₂O was subjected to XRD studies which revealed a monoclinic crystal system. In vitro, biological screening effects of the compounds were tested against two bacterial species Staphylococcus aureus and Escherichia coli. DNA cleavage and antioxidant activity of the ligands and their respective complexes were also examined.