Crystal structures and antibacterial properties of Cu(II) complexes containing an unsymmetrical N<inf>2</inf>O Schiff base ligand and bidentate N-donor heterocyclic co-ligands

Three new Cu(II) Schiff base complexes with bidentate N-donor heterocyclic co-ligands, 2,2'-bipyridine (1), 1,10-phenanthroline (2), and 2,9-dimethyl-1,10-phenanthroline (3), were synthesized and characterized by FT-IR and UV-vis spectroscopy. Molecular structures of [C20H21CuN4O](ClO4) (1) and [C24H25CuN4O](ClO4) (3) were characterized by single-crystal X-ray crystallography. The Schiff base ligand is an N2O-type ligand, which is the mono-condensed form of the reaction between 1,3-propanediamine and salicylaldehyde. The antibacterial activities of these complexes were investigated against one gram positive and four gram negative bacteria. Considerable antibacterial activity was obtained against both gram type bacteria. Complexes 2 and 3 with 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline, respectively, showed better antibacterial activity compared to 1 which has the 2,2'-bipyridine co-ligand