Pyridine-derived Schiff base copper (II), zinc (II), and cadmium (II) complexes: Synthesis, structural properties, biological evaluation, and docking studies

Herein, Cu (II), Zn (II), and Cd (II) complexes, [DEP(M)X-2], encompassing the pyridine-derived Schiff-base ligand DEP, where DEP is (E)-N,N-diethyl-2-([pyridine-2-ylmethylene]amino)ethane-1-amine, are synthesized. X-ray diffraction studies reveal distorted square pyramidal geometries for the Cd (II) and Cu (II) complexes, whereas the geometry of [DEP (Zn)Cl-2] can best be described as trigonal bipyramidal. The antibacterial potential of DEP and its [DEP(M)X-2] complexes were evaluated against four bacterial strains: Salmonella typhi, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa; five fungal strains: Candida glabrata, Candida albicans, Microsporum canis, Fusarium solani, and Aspergillus flavus; and Leishmania major protozoan. Complexes exhibited superior bactericidal, fungicidal, and leishmanicidal inhibition potential against all tested microbes compared with the free ligand. The preliminary cytotoxic activity of [DEP(M)X-2] complexes on breast and colon carcinoma cells, that is, MCF-7cell line and HCT-116 cell line, respectively, revealed that studied complexes showed high cytotoxicity compared with ligand (DEP). Among the studied complexes, [DEP (Cd)Br-2] exhibited an excellent inhibitory profile, as confirmed by the docking study. The molecular docking studies showed a good correlation between the biological activities of synthesized metal complexes and docking studies. We have confidence in the contribution of these complexes toward the design of new metal-derived candidates that can treat infectious diseases.

Automated summary

Cu (II), Zn (II), and Cd (II) complexes, [DEP(M)X-2], with a pyridine-derived Schiff-base ligand DEP, were synthesized. The complexes exhibited distorted square pyramidal and trigonal bipyramidal geometries. The DEP complexes showed superior antibacterial, fungicidal, and leishmanicidal inhibition potential compared to the free ligand. Additionally, the complexes exhibited high cytotoxicity against breast and colon carcinoma cells. The docking study confirmed the excellent inhibitory profile of [DEP (Cd)Br-2]. Overall, these complexes have the potential to be used in the development of new metal-derived candidates for the treatment of infectious diseases.