Synthesis, structure, DNA/BSA binding, antibacterial and molecular docking studies of tetradentate ONNO schiff base metal complexes

•A new schiff base ligand 3-bis((E)−2 hydroxy-3-methoxybenzylidene)amino) malononitrile was synthesized.•The calorimetric technic was employed to study the DNA binding to BSA.•The metal complexes of Cu, Ni, and V-VDMN have shown significant activity against both gram-positive and negative bacteria.•The structure of VDMN, Cu-VDMN, Ni-VDMN and V-VDMN using DFT techniques to study the effect of electron contact on the improvement of geometrical properties. A new Schiff base ligand 3-bis((E)-2 hydroxy-3-methoxybenzylidene)amino) malononitrile was synthesized by combining O-vanillin and 2, 3-diaminomaleonitrile. This ligand was subsequently complexed with Copper (II), Nickel (II) and Vanadyl (IV) metal ions. Using FT-IR, NMR and MS spectroscopic techniques, the synthesized malononitrile ligand and the Copper (II), Nickel (II) and Vanadyl (IV) metal complexes were investigated. The reliability of the geometrical parameters of the synthesized Copper (II), Nickel (II) and Vanadyl (IV) metal complexes was confirmed by electronic spectra, EPR analysis, and magnetic moment measurements. The calorimetric technic was employed to study the DNA binding to BSA. Concerning the Gram-positive and Gram-negative bacterial species Bacillus substilis, Staphylococcus aureus, Escherichia coli, Pseudomonas fluorescens, and Bacillus cereus, all of the metal complexes under investigation demonstrated antibacterial activity when compared to tetracycline. When Schiff base and its metal complexes were screened for in vitro antioxidant activity, the Ni(II) complex had better antioxidant activity than the ligand and other metal complexes, which was further substantiated by molecular docking. [Display omitted]