Antibacterial Studies of Leucine Complexes of Fe (III) and Cu (II)

Fe (III) and Cu (II) complexes of leucine were synthesised and characterized. The inhibition strengths of these complexes against some bacteria were evaluated. It was found that the max of the complexes were at 670 nm and 650 nm for Cu-leu and Fe-leu respectively. There was an observed red shift between the max of the metal salts and their complexes. This shift is a strong implication of coordination. The conductance of the complexes in water was 330.00 S and 17.60 S for Cu-leu and Fe-leu respectively. The IR frequencies of the leucine due to +NH3 group found at 1533.46 cm-1 and 2616.53 cm-1 disappeared in the complexes, indicating coordination through +NH3. Also the peaks for s (COO-) in the leucine was 1389.76cm-1. This band was decreased to 1379.15 cm-1 and 1385.90 cm-1 for Cu-leu and Fe-leu respectively. These changes also portend coordination of the leucine to these metal ions via carboxylate. Again, IR bands for Cu-leu and Fe-leu at 3241.48 cm1 and 3372.66 cm1 are firm evidence of the presence of coordinated water molecules in the complexes. The Fe and Cu ions are thus coordinated to the ligand via carboxylate (COO-) and H3N+ groups in a bidentate fashion. Octahedral and square pyramidal geometry were proposed for the Fe-leu and Cu-leu complexes respectively. The results of the antimicrobial screening by agar diffusion with these amino acids complexes showed increased antibacterial activities when compared to their salts.