Copper(II) Complexes Bearing Unsymmetrical NNO-Tridentate Schiff Bases: Synthesis, Spectral Characterization, Electrochemical Behaviour and their Biological Activity

In this work, three mono-condensation Schiff bases of o-phenyldiamine with 5-t-butylsalicylaldehyde (AIBP), 3,5-di-t-butylsalicylaldehyde (AIdBP) and 2-hydroxy-1-naphthaldehyde (AINA) were prepared and coordinated by CuCl2·2H2O without and with the presence of pyridine to form six tridentate Schiff base copper(II) complexes. The synthesized unsymmetrical Schiff base copper(II) complexes were characterized by diverse physico-chemical methods like mass, infrared, ultraviolet-visible spectroscopies and magnetic susceptibility measurements to indicate that the coordination of copper(II) with the synthetic Schiff bases at NNO atoms and the geometry around central ion is distorted square-planar or square-pyramidal probably. Then electrochemical properties of the obtained Schiff base copper(II) complexes were studied using cyclic voltammetry (CV). [Cu(II)(AINA)Cl] has exhibited that the peak current increases with the increase of the scan rates linearly. All the Schiff base copper(II) complexes have been screened for their in vitro antibacterial activity on Gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, Lactobacillus fermentum. [Cu(II)(AIdBP)Cl] has expressed the effective activity for all three tested bacteria. The in vitro cytotoxicity of the synthetic Schiff base copper(II) complexes for human cancer cell lines, MCF-7 and HepG-2, were examined as well.