Synthesis, characterization and cytotoxic evaluation of metal complexes derived from new N′-(2-cyanoacetyl)isonicotinohydrazide

The novel ligand (H₂L), N'-(2-cyanoacetyl)isonicotinohydrazide, has been synthesized via reacting the isonicotinic hydrazide with 1-cyanoacetyl-3,5-dimethylpyrazole. The keto-form of the free ligand has been evoked from its spectral data. Based on elemental analyses and mass spectra, the ligand formed 1:1 (M: L) metal complexes with the acetate salts of Cu(II), Co(II), Ni(II) and Zn(II). The complexes' spectral analyses revealed that the ligand behaved as a mononegative bidentate via the hydrazonyl N¹ and deprotonated enolized acetyl oxygen. Moreover, the DFT quantum chemical calculations revealed that the ligand had higher HOMO and lower LUMO energies than metal complexes, implying an electron donating character. Furthermore, the in vitro anticancer activity against HepG2 and HCT-116 cell lines displayed that the ligand was more potent than doxorubicin against both cell lines, although the metal complexes displayed lower efficacy.