Synthesis, spectral characterization, and biological studies of Schiff bases and their mixed ligand Zn(II) complexes with heterocyclic bases

Abstract

In the present study, six mononuclear Zinc(II) complexes, [Zn(L1)(6-Methyl-2,2′-bpy)] (1), [Zn(L1)(1,10-Phen)] (2), [Zn(L1)(5-Amino-1,10-Phen)] (3), [Zn(L2)(6-Methyl-2,2′-bpy)] (4), [Zn(L2)(4,4′-Di-tert-butyl-2,2′-bpy)] (5), and [Zn(L2)(1,10-Phen)] (6) formed from Schiff bases, 2-methyl-1-phenyl-1-(pyridin-2-ylmethylimino)propan-2-ol (L1) and 4-chloro-5-methyl-2-(1-(pyridin-2-ylmethylimino)ethyl)phenol (L2) were synthesized. The synthesized Schiff base ligands and metal complexes were characterized by different spectroscopic techniques such as FTIR, UV–Visible, 1H & 13C NMR spectroscopy, in addition to Powder X-ray diffraction and cyclic voltammetry. Further, the synthesized metal complexes (1–6) and their parental Schiff bases (L1, L2) were evaluated for antibacterial, antifungal, and antioxidant activities. Of those, Complex 1 was shown to have significant antibacterial activity against all of the evaluated microorganisms. Schiff base ligands, L1 and L2, complexes 1, 4, and 5 were shown to have superior antifungal activity against Aspergillus niger than the standard drug, fluconazole. In addition, the synthesized compounds achieved good antioxidant activities when compared to the standard Ascorbic acid.