Experimental and theoretical studies on structural aspects of transition metal complexes of isonicotinoyl N‐oxide hydrazone: Their DNA‐binding interaction and cytotoxicity

Abstract

Equilibrium studies of isonicotinoyl N‐oxide hydrazone [4‐(2‐(4‐(diethylamino)‐2‐hydroxybenzylidene) hydrazine carbonyl) pyridine1‐oxide] were carried out by employing pH‐metric titrations in 40% DMF‐H2O medium at 303 K and 0.1 M ionic strength, to investigate its ligation properties. Quantitative structure activity relationship (QSAR) and molecular orbital properties were evaluated by applying HyperChem 7.5 tools. The title compound and its Cu (II), Ni (II), and Zn (II) complexes were characterized by various spectro analytical tools, namely, Fourier‐transform infrared spectroscopy, 1H‐nuclear magnetic resonance, liquid chromatography‐mass spectrometry, UV‐Vis, thermogravimetric analysis–differential thermal analysis, scanning electron microscope (SEM)–energy‐dispersive X‐ray, electron spin resonance, and X‐ray diffraction (XRD) studies. Infrared data provided information about the chelating properties of ligand and coordination sites in metal complexes. The electronic spectral studies of complexes inferred the symmetry‐based spin allowed electronic transitions and charge transfer (CT) transitions. Mass spectral studies, elemental analysis, and thermal studies of complexes confirmed the composition of the metal complexes. The surface texture and nanocrystalline nature of solid compounds were studied by SEM and XRD methods. The antioxidant activities of all the compounds were determined by DPPH radical scavenging method. DNA‐binding interactions of the synthesized compounds with calf thymus (CT)‐DNA were studied by absorption and fluorescence methods. Antioxidant and antimicrobial studies indicated their potentiality as active agents. Cytotoxicity measurements of title compounds for IC50 values on MCF‐7 cell line, and docking scores of these compounds with chosen target, computed by employing AutoDock software indicated their potential for anticancer properties.