New copper(II) and zinc(II) complexes based on azo Schiff base ligand: Synthesis, crystal structure, photoisomerization study and antibacterial activity

Abstract

Newly synthesized mononuclear copper(II) and zinc(II) complexes containing an azo Schiff base ligand (L), prepared by condensation of 2‐hydroxy‐5‐(o‐tolyldiazenyl)benzaldehyde and propylamine, were obtained and then characterized using infrared and NMR spectroscopies, mass spectrometry and X‐ray diffraction. Ligand L behaves as a bidentate chelate by coordinating through deprotonated phenolic oxygen and azomethine nitrogen. The copper and zinc complexes crystallize in triclinic and orthorhombic systems, respectively, with space groups P−1 and Pca21. In these complexes, the Cu(II) ion is in a square planar geometry while the Zn(II) ion is in a distorted tetrahedral environment. The photochemical behaviors of ligand L, [Cu(L)2] and [Zn(L)2] were investigated. The azo group in L underwent reversible trans–cis isomerization under UV and visible irradiation. This process was inhibited for the complexes. In addition, ligand L and its copper and zinc complexes were assessed for their in vitro antibacterial activities against four pathogenic strains.