Synthesis, characterization and antimicrobial activities of a Schiff base derived from phenylalanine and acetylacetone and its Mn(II), Ni(II) and Cu(II) complexes

Abstract

Complexes of Cu(II), Ni(II) and Mn(II) with a Schiff base derived from condensation reaction of phenylalanine and acetylacetone have been synthesized and characterized analytically and spectroscopically. Melting point of the Schiff base was 188^oC and the complexes decompose within a temperature range of 210-242^oC. The molar conductance values of the complexes were found to be within 15.0-60.0Ω^-1cm²mol^-1 range while the magnetic moment values indicated the complexes to be paramagnetic. The Infrared spectra of the Schiff base showed the azomithine peak at 1605cm^-1 which shifted to 1595-1637cm^-1 in the complexes. The analytical and spectral studies revealed that all the metal complexes are in 1:2 Metal-Ligand ratios, with the Schiff base acting as a tridentate ligand towards metal ion via azomethine-N, deprotonated-O of carboxylic group and enolic-O group of acetylacetone. The synthesized ligand and its respective metal (II) complexes were screened for their antibacterial activity against Staphylococcus aureus (Gram-positive), Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Klebsiella pneumoniae (Gram-negative) bacterial strains and antifungal activity against Candida albicans, Fusarium solani and Aspergillus fumigatus. The results revealed that, the Schiff base and the metal complexes showed significant antibacterial and antifungal strength at high concentrations.

Keywords: Acetylacetone, Schiff base, complex, antimicrobial, characterization