Synthesis, Spectroscopic Characterization and Biological Studies of Some Metal(II) Complexes of Nicotinic Hydrazide Moiety

In this study, a new ligand N′-(1-(2-oxo-2H-chromen-3-yl)ethylidene)nicotinohydrazide was synthesized and characterized. Then, the ligand was reacted with Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions affording its metal(II) complexes. Through elemental analysis, molar conductance, magnetic data, UV-visible, FT-IR, 1H NMR and mass spectra, the structural characterization of all the metal(II) complexes were accomplished. The FT-IR data demonstrated that in the metal(II) complexes, the ligand chelated to metal ion in a tridentate manner. The UV-visible spectral and magnetic data showed that the complexes exhibit octahedral geometry. Additionally, ligand molecular docking studies were conducted. The antimicrobial study demonstrated that complex formation increased the free ligand activity. The Cd(II) complex is an efficient antifungal agent, whereas the Zn(II) and Cd(II) complexes may be regarded as promising antibacterial agents. Moreover, Cd(II) complex also demonstrated strong anti-TB properties against M. tuberculosis. The antioxidant activity results showed that the except Cd(II) complex, other metal(II) complexes were found to be more active than the parent ligand.