Spectral, Structural and Cytotoxicity Studies on the newly synthesized N'1,N'3-diisonicotinoylmalonohydrazide and some of its bivalent metal complexes

Abstract The reaction of diethyl malonate with isonicotinic hydrazide resulted in the formation of a new ligand, N'1,N'3-diisonicotinoylmalonohydrazide (H4INM), which was characterized by elemental and spectral studies. The existence of the free ligand in keto form was shown by its spectral data. The ligand reacted with Cu(II), Co(II), Ni(II) and Zn(II) acetates to produce bimetallic complexes. The ligand chelated to the metal ion in binegative tetradentate fashion via malonyl carbonyl oxygen and N2H atoms except in Zn(II) complex, where it acted as neutral tetradentate through the isonicotinyl carbonyl oxygen and N1H atoms. The various spectral measurements revealed that all complexes had an octahedral geometry except the Cu(II) complex which has square planar structure supported by the ESR spectral data. Moreover, the DFT quantum chemical calculations were performed and the HOMO-LUMO energy gap of the ligand and complexes were comparable to the optical band gap (Eg) estimated using Tauc's equation. Furthermore, isolated compounds’ in vitro cytotoxic activity against Hela (Epithelioid Carcinoma) and WISH (Human amnion) cell lines of was investigated. According to the results, the ligand exhibits moderate and weak effect against the Hela and WISH cell lines, respectively. While, the metal complexes exhibited more potent effect against WISH than against Hela, with IC50 ranging from 23.65 ± 1.7 to 46.28 ± 3.4 and 56.36 ± 3.5 to 83.88 ± 4.7 µM, respectively.