New bivalent metal chelates based on an NO-donor Schiff base ligand: synthesis, structural characterization, DFT simulation, biological evaluation, and molecular docking analysis

It is crucial to establish a correlation between the chemical structure of transition metal chelates and their anticipated biological activity to create efficient bioinorganic medications. Thus, new bivalent transition metal chelates; M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), were easily synthesized from an innovative bidentate NO-donor Schiff base ligand (HL). A comprehensive series of physicochemical techniques like FT-IR, 1H NMR, ESR, TGA and UV-Vis spectroscopy was used to characterize the synthesized compounds. The metal is evidently coupled to two ligands through the deprotonated enolic oxygen and nitrogen atoms of imine groups in all chelates. The obtained analytical and spectroscopic data revealed that the chelates of Mn(II), Co(II), Ni(II) and Cu(II) adopted octahedral structures with two coordinated water molecules. On the other hand, the Zn(II) chelate was found to be a tetrahedron, while the Cd(II) one was a distorted tetrahedron. The energy optimized geometry of HL and some of its chelates as well as their quantum reactivity descriptors were estimated by DFT analysis. The antimicrobial and cytotoxicity screening exhibited that the compounds were bioactive with various biological activities. In addition, the binding interaction characteristics of the ligand and the Cu(II), Zn(II) and Cd (II) chelates were validated by molecular docking processes using three macromolecular biological receptors (Aureolysin, Staphylococcus Aureus metalloproteinase (1BQB), a penicillin-binding protein 3 from Escherichia Coli (4PJP) and a B-DNA (1BNA). The biological findings were correlated with the calculated DFT data and molecular docking results.