New mixed-ligand thioether-quinoline complexes of nickel(II), cobalt(II), and copper(II): Synthesis, structural elucidation, density functional theory, antimicrobial activity, and molecular docking exploration

The main purpose of the current work is the design and synthesis of new Co(II), Ni(II), and Cu(II) mixed-ligand complexes derived from simple and easily synthesized azo-ligand, [2-(phenylthio)phenyl]diazenyl}-2-naphthol (HTe), with 8-hydroxyquinoline (HQ) to improve and understanding their action as an antimicrobial candidate and their therapeutic efficiency with the aid of density functional theory (DFT) calculations and molecular docking studies, which considered a hot topic of research. To access this target, and to explore the effect of changing metal ion type, the new Co(II), Ni(II), and Cu(II) mixed-ligand complexes were firstly synthesized and characterized via elemental analysis, Fourier transform infrared (FT-IR), mass spectrometry, ultraviolet-visible spectroscopy, magnetic susceptibility, thermogravimetric analysis (TGA), and stoichiometry analysis molar ratio method. Upon further inspection, the octahedral structures of the isolated metal complexes were found. The compounds' molecular structures were optimized using the DFT technique, and the quantum chemical parameters were evaluated. To determine whether or not these compounds are effective in preventing the spread of harmful bacteria and fungi, two of the most common environmental pollutants in the Arab world, a disc diffusion test was conducted. The prepared complexes were much more efficient against bacteria than the pristine ligands. Molecular docking experiments helped researchers learn which medicines inhibited the 1fj4 protein. All other tested compounds were found to have lower binding affinities than CuTeQ. This suggests that these compounds have the potential as starting points for the production of new classes of antibiotics. Finally, a correlation of the in vitro activity with the DFT and molecular docking data has been done and discussed.