Synthesis, Characterization, Spectral Analyses, Antimicrobial Activities, and Computational Studies of Some Transition Metal Complexes of N’-(2-oxo-2H-chromen-4-yl) Nicotinohydrazide

Abstract

The metal complexes Cu (II), Zn (II), and Co (III) complexes of (N’-(2-oxo-2H-chromen-4-yl) nicotinohydrazide, a derivative of nicotinic acid hydrazide condensed with 4-hydroxycoumarin, have been synthesized. The ligand and its metal complexes were characterized by various physico-chemical and spectroscopic tools, viz: Elemental Analysis, FT-IR, TGA, 1H NMR, UV-visible, molar conductance, and magnetic susceptibility as well as theoretical computation. On the basis of these analyses, the ligand was found to coordinate to metal ions in a tridentate mode through the nitrogen atom of the azomethine group and the oxygen atom of the ketonic groups. The spectral and magnetic data allowed for the chemical structures of the metal complexes to be predicted, wherein octahedral geometry was assigned to the Co (III) complexes, while tetrahedral geometry was assigned to the Cu (II) and Zn (II) complexes; this was further explored in a DFT calculation. Conductance measurement suggested the non-electrolytic nature of the compounds. The anti-tubercular activities of the compounds showed zinc (II) and copper (II) complexes having identical activity to the reference drugs, pyrazinamide and isoniazid, while the cobalt (III) complex had the highest MIC value compared to the reference drugs and parent ligand.