Mixed-ligand copper complexes with unsymmetrical tridentate Schiff base ligands and 2,2′-bipyridine: Synthesis, x-ray crystallography and antibacterial properties

Abstract

Three new mixed-ligand Cu(II) complexes with general formula [CuLx(2,2′-bipyridine)]ClO4 (x = 1–3) where synthesized and characterized by x-ray crystallography, elemental analyses, and spectroscopic techniques such as FTIR and UV–Vis spectroscopy. The complexes contain an unsymmetrical Schiff base ligand (Lx) and one 2,2′-bipyridine co-ligand. The Schiff base ligands are NN’O type unsymmetrical ligands which are the mono-condensed form of the reactions between meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde (1), 5-bromosalicylaldehyde (2) or 3-methoxysalicylaldehyde (3). Antibacterial activity of the new complexes along with their parent complexes, i.e. [CuLx(pyridine)]ClO4(1a-3a) were studied against 2 g negative bacteria (E. Coli and K. Pneumonia) and 2 g positive bacteria (S. aureus and B. Subtilis). The complexes were almost inactive against the studied gram negative bacteria but showed very good activity against the studied gram positive ones.