N′-(Furan-2-ylmethylene)-2-hydroxybenzohydrazide and its metal complexes: synthesis, spectroscopic investigations, DFT calculations and cytotoxicity profiling

Abstract

The ligand, N′-(furan-2-ylmethylene)-2-hydroxybenzohydrazide (H₂L), was synthesized characterized through various spectral studies which cleared out that the free ligand existed in keto form. The ligand upon reaction with Cu(II), Co(II), Ni(II) and Zn(II) acetates yielded complexes with stoichiometric ratio 1:2 (M:L) which has been validated through the elemental and mass spectral measurements. The IR and NMR spectral studies of the isolated complexes disclosed that the ligand chelated to metal ion in mononegative bidentate fashion via the azomethine nitrogen and deprotonated enolized carbonyl oxygen. Moreover, the DFT quantum chemical calculations designated that the ligand and Ni(II) complex exhibited the highest and lowest values of HOMO, LUMO energies and HOMO-LUMO energy gap, respectively. Furthermore, the in vitro cytotoxic activity towards HePG-2 and HCT-116 cell lines of the isolated compounds was investigated and the data cleared out that the ligand was more potent than the metal complexes.