Synthesis, characterization, potential antimicrobial, antioxidant, anticancer, DNA binding, and molecular docking activities and DFT on novel Co(II), Ni(II), VO(II), Cr(III), and La(III) Schiff base complexes

In this study, five novel complexes for Co(II), Ni(II), VO(II), Cr(III), and La(III) ions were synthesized from a tridentate NNO monobasic chelating Schiff base ligand, (Z)‐2‐((pyridin‐2‐ylimino)methyl)phenol (HL). Spectral and analytical tools were applied to elucidate the structural compositions of the new compounds. Then, geometry optimization was conducted for all the syntheses by the Gaussian 09 program via the density functional theory method to obtain optimal structures and the most essential parameters. Moreover, the biochemical behaviors of all the syntheses were explored based on the reactivity, which was tested against various cancer cell lines (HepG‐2, MCF‐7, and HCT‐116). The complexes exhibited an interestingly antiproliferative potential against human cancer cell lines, and the cytotoxicities of the new complexes were arranged to follow the order: VOL > CrL > NiL > LaL > CoL > HL. The antioxidant behaviors of the complexes were studied using the DPPH assay, and VOL showed the maximum antioxidant activity, followed by LaL. The antibacterial activities of the HL ligand and its complexes were studied. Moreover, the binding nature of the complexes with calf thymus DNA (CT‐DNA) was investigated based on the spectrophotometric absorption titration, viscosity, and gel electrophoresis methods. The binding ability of the complexes with CT‐DNA was proposed to be just intercalation or replacement mode. The intrinsic binding constant K b was calculated and arranged based on the following order: VOL (5.2 × 10 5 ) > CrL (3.6 × 10 5 ) > NiL (3.3 × 10 5 ) > LaL (3.0 × 10 5 ) > CoL (1.12 × 10 5 ) mol −1 dm −3 . Docking investigations were performed using the receptors of COVID‐19's main protease viral protein (PDB ID: 6LU7) and Escherichia coli (gram [–ve] bacteria [PDB ID: 1fj4]).