Characterization, DFT, DNA, Biological Applications, and In Silico Studies of Mn(II), VO(II), Pd(II), and Cd(II) Complexes Derived From Chromone Isonicotinic Hydrazone Ligand

ABSTRACT A novel Schiff base ligand, ((4‐oxo‐4H‐chromen‐3‐yl)methylene)isonicotinohydrazone (HL), in addition to its VO(II), Cd(II), Mn(II), and Pd(II) complexes, were prepared and identified. Various analytical techniques such as elemental, TGA, and magnetic susceptibility measurements, additionally, nuclear magnetic resonance (NMR) spectroscopy of hydrogen and carbon‐13, MS, FT‐IR, EPR, and electronic (UV‐VIS) spectroscopy, are utilized and proposed that HL has a mono‐negative tridentate mode of chelation with VO(II) and Mn(II) complexes, whereas it displays a mono‐negative bidentate with the Cd(II) complex and a neutral bidentate with the Pd(II) chelate. The crystallographic structures and atomic spacing for both HL and its complexes were examined through powder X‐ray diffraction analysis. Moreover, electrochemical analyses were conducted on Cd(II) and Mn(II) metal ions with and without the agent that chelates for the purpose of foreseeing the consequences of complex interactions in the case of the liquid phase. Furthermore, photoluminescence study was applied on VO(II) and Pd(II) complexes and showed a quenching effect for both. The ligand's geometry and its complexes were examined through calculations based on density functional theory (DFT) using B3LYP/LANL2DZ computational method and showed molecular electrostatic potential, chemical reactivity, and FMOs. The Cd(II) complex showed promising results against various bacterial strains, displaying excellent activity that exceeded that of the standard, Gentamicin (108% against K. pneumoniae , 100% against Salmonella , and 90.47% against A. fungi ). In contrast, it exhibited no cytotoxicity toward the MCF‐7 cell line. However, in a DNA binding study, the compound demonstrated significant activity as its concentration increased up to 6 mM, suggesting its potential for use in cancer therapy due to its ability to inhibit DNA replication.