Syntheses,characterizations, crystal structures,and biological activities of two new mixed ligand Ni(II) and Cu(II) Schiff base complexes

Two mixed-ligand complexes, [Cu(L)(2imi)] (1) and [Ni(L)(2imi)]·MeOH (2) [L = 2-(((5-chloro-2-oxyphenyl)imino)methyl)phenolato) and 2imi = 2-methyl imidazole], have been prepared by the reaction of appropriate metal salts with H₂L and 2-methyl imidazole. Their structures were characterized by microanalysis, FT-IR, UV–vis, molar conductivity, and ¹H NMR for [Ni(L)(2imi)]·MeOH. The structures were determined using single crystal X-ray diffraction. Each four-coordinate metal center, Cu(II) in 1 and Ni(II) in 2, is surrounded by donors of Schiff base (L^2?) and N of 2-methyl imidazole in square planar geometries. α-Amylase activities of these compounds have also been investigated. The experimental data showed that α-amylase was inhibited by Ni(II) complex while the Cu(II) complex causes a 1.3-fold decrease in K_m value. Antimicrobial results show that these compounds, especially the Cu(II) complex, have potential for antibacterial activity against Gram negative and Gram positive bacteria and antifungal activity against Aspergillus fumigatus.