Some new Cu(II) complexes containing an ON donor Schiff base: Synthesis, characterization and antibacterial activity

Abstract

Six new copper(II) complexes, CuLCl·H 2O ( 1), CuL(NO 3)·2H 2O ( 2), [Cu(L) 2] ( 3), CuL(SCN)·2H 2O ( 4), CuL(ClO 4)·2H 2O ( 5) and (CuL) 2(SO 4)·4H 2O ( 6), where HL = 1-phenyl-2,3-dimethyl-4-(N-2-hydroxy-4-methoxy-benzaldehyde)-3-pyrazolin-5-one, have been synthesized. The characterization of the newly formed compounds was done by 1H NMR, UV–Vis, IR, ESR spectroscopy, elemental analysis and molar electric conductivity. The crystal structure of 1-phenyl-2,3-dimethyl-4-(N-2-hydroxy-4-methoxy-benzaldehyde)-3-pyrazolin-5-one has been determined by X-ray diffraction studies, as well as the crystal structure of one of its copper(II) complexes, [Cu(L) 2] ( 3). The copper atom is coordinated to two nitrogen and two oxygen atoms of the Schiff base ligand. The in vitro antibacterial activity against Klebsiella pneumoniae ATCC 100131, Staphylococcus aureus var. Oxford 6538, Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 10536 strains was studied and compared with that of free ligand. The anti-microbial activity was dependent on the microbial species tested and the metal salt anion used.