Novel Imine Complexes Incorporating ZrO(II), VO(II), and Pd(II) Cations: Synthesis, DFT Calculation, Molecular Docking, Antimicrobial, and Antitumor Activity

Abstract

Novel imine complexes of ZrO(II), VO(II), and Pd(II) have been synthesized and described using IR, TGA, UV/Vis, and 1HNMR methods, along with powder X‐ray diffraction (XRD), elemental (CHN) analysis, mass spectrometry, molar conductance, and magnetic susceptibility measurements. Conductivity measurements indicate that none of the complexes function as electrolytes. Magnetic susceptibility data confirm the paramagnetism of the VO(II) complex, while ZrO(II) and Pd(II) complexes exhibit diamagnetic properties. Various analyses suggest that divalent cations favor a 1:1 metal‐to‐ligand ratio. Biological studies demonstrated that all complexes possess significant antimicrobial activity against a range of bacterial and fungal strains. We also observed that the antimicrobial potency of the metal complexes follows the order: ZrO(II) > Pd(II) > VO(II) > H2A, with the ZrO(II) complex showing the highest inhibition zone (28 mm) against Gram‐negative bacteria. The antifungal activity against Aspergillus flavus increases in the order VO(II) > ZrO(II) > Pd(II) > H2A. Additionally, the complexes exhibit high cytotoxicity against carcinoma cell lines, including the HepG‐2, when compared with the clinically proven vinblastine. Density functional theory (DFT) calculations were performed to elucidate the equilibrium geometry of the imine ligand and its complexes at the B3LYP level of theory, using the Gaussian 09 program with 6‐311G++(dp) basis set for C, H, O, N, and Cl atoms, and lanl2dz for Pd, V, and Zr atoms. Finally, docking studies revealed potential binding modes at the active sites of bacterial and fungal receptors.