Photocatalytic, molecular docking, DFT and DNA interactions of some 4-aminoantipyrine derived schiff base metal (II) complexes

Co(II), Ni(II), Cu(II), and Zn(II) complexes were synthesized from a Schiff base ligand using their respective acetate salts and characterized by CHN analysis, mass spectrometry, IR, UV–Vis, and p-XRD techniques. Spectroscopic studies confirmed coordination through the azomethine nitrogen atoms, leading to square-planar metal complexes, while p-XRD analysis revealed their nanocrystalline nature. Cyclic voltammetry demonstrated irreversible redox behavior, and thermal analysis supported the proposed structures. The photocatalytic performance of the complexes was evaluated by the degradation of methylene blue under visible light irradiation, with the Cu(II) complex exhibiting the highest degradation efficiency. Molecular docking studies revealed strong binding affinities toward the selected target proteins, which correlated well with the observed biological activities. DNA-binding studies demonstrated significant interactions with calf thymus DNA. Biological screening against four bacterial strains (B. subtilis, S. aureus, E. coli, and K. pneumoniae) and two fungal strains (A. niger and C. albicans) revealed significant antimicrobial potential, with the Cu(II) complex exhibiting the highest cytotoxic efficacy against the SK-MEL-28 cancer cell line. DFT calculations, including frontier molecular orbital (HOMO–LUMO) analysis and chemical reactivity descriptors, supported the experimental findings. Overall, the Cu(II) complex emerged as a promising candidate for photocatalytic and biomedical applications.