Synthesis, characterization and antimicrobial activity of Co(II), Zn(II) and Cd(II) complexes with N-benzyloxycarbonyl-S-phenylalanine

In this paper the first complexes of M(2+) ions (M(2+) = Zn(2+), Cd(2+) and Co(2+)) with N-benzyloxycarbonyl-S-phenylalaninato ligand (1-3) are described. The new complexes were characterized by means of elemental analysis, IR and UV-vis spectroscopy, molar conductivity measurements and (1)H, (13)C and (15)N NMR spectroscopy (1D and 2D). The Co(II) complex adopts an octahedral geometry, and the Zn(II) and Cd(II) complexes adopt a tetrahedral one. For the first time, the antimicrobial activity of N-benzyloxycarbonyl-S-phenylalaninato ligand (N-Boc-S-phe) and the complexes 1-3 was investigated against gram-positive: Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Bacillus subtilis and gram-negative bacteria: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and two strains of the yeast Candida albicans. It was shown that the complexes were effective against most strains. The best activity was detected against the yeast C. albicans.