Synthesis, structural characterization, QSAR and docking studies of a new binuclear nickel (II) complex based on the flexible tetradentate N-donor ligand as a potent antibacterial and anticancer agent

Abstract

A new nickel (II)complex namely [Ni2(Lt)Cl4] derived from the NiCl2.6H2O and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (Lt) has been synthesized and fully characterized by the single crystal X-ray diffraction, elemental analysis, FT-IR, UV–vis, density functional theory (DFT) calculations, antibacterial and anticancer activities. In the title complex, each of the Ni(II) atoms is tetrahedrally coordinated by two N atoms from one of the chelating bidentate bis(3,5-dimethylpyrazolyl)methane units of the Lt ligand and two Cl as terminal ligands. The neighboring [Ni2(Lt)Cl4] molecules are linked together by the intermolecular CH⋯Cl hydrogen bonds to generate a 1D chain structure. The chains are further stabilized by the intermolecular CH⋯π interactions to form a two-dimensional non-covalent bonded structure. The antibacterial activity of the free Lt ligand and its Ni (II) complex shows that the ability of these compounds to inhibit growth of the tested bacteria increase from the Lt to binuclear nickel (II) complex. Scanning probe microscopy (SPM) study of the treated B. subtilis and E. coli bacteria was implemented to understand the structural changes caused by the interactions between the nickel (II) complex and the target bacteria. The cytotoxicity test of the Lt ligand and its complex was evaluated against the human carcinoma cell line (Caco-2) using the MTT assay. The results indicate that the Lt ligand and its complex display cytotoxicity against Caco-2 with the IC50 values of 36.29μM and 12.97μM, respectively. Therefore, the complex can be nominated as a potential anticancer agent. Molecular docking investigations on the five standard antibiotic, five standard anticancer drugs, free Lt ligand, title complex and twelve receptors were performed by Autodock vina function. The results of docking and DFT calculations are in line with the in vitro data obtained via the antibacterial and anticancer activity of Lt ligand and its made-complex.