Transition metal complexes of N'-(2-cyanoacetyl)nicotinohydrazide: Synthesis, structural and anticancer activity studies

Abstract

On reacting the nicotinic hydrazide with 1-cyanoacetyl-3,5-dimethylpyrazole, a new ligand, N'-(2-cyanoacetyl)nicotinohydrazide (H2L), was produced and characterized using diverse spectral studies which cleared out that the free ligand existed in keto form. The ligand reacted with Cu(II), Co(II), Ni(II) and Zn(II) acetates affording metal complexes with 1:1 (M:L) stoichiometric which was validated using the elemental and mass spectral measurements. The spectral studies of the isolated complexes showed that the ligand chelated to metal ion in mononegative bidentate fashion via the amide nitrogen and deprotonated enolized carbonyl oxygen group. Moreover, the DFT quantum chemical calculations indicated that the ligand has the highest HOMO-LUMO energy gap, ΔEH-L, while the Co(II) complex has the lowest and may be sorted as H2L > Zn(II) > Cu(II) > Ni(II) > Co(II). Furthermore, isolated compounds’ in vitro cytotoxic activity against HePG-2 and HCT-116 cell lines was investigated and the data cleared that the ligand has very strong, IC50 6.59 ± 0.4 and 8.17 ± 0.7 μM, respectively. Whereas, the metal complexes exhibited moderate to weak potent effect against both cell lines.