Spectrophotometric investigation of DL-tryptophan in the presence of Ni(II) or Co(II) ions

Abstract

In the present study, synthesis of transition metal complexes of DL-tryptophan with metal precursors such as nickel (II) and cobalt (II) ions in water under refluxing conditions and optimization of the reactions to obtain the composition of complexes in water solutions has been reported. The preparation and structural elucidation of the complexes was undertaken by using physico-chemical, potentiometric titration and spectroscopic methods (UV/Vis, FT-IR and XRD). Comparisons of the spectral measurements of DL-tryptophan with those of the nickel (II) and cobalt (II) complexes are useful in determining the atoms of the ligand that are coordinated to the metal ion. In addition, K (dissociation constant) and ΔG (Gibbs free energy) values were calculated using the Babko and Stanley & Turners methods. Antibacterial and antifungal activities of the complexes were studied screened against bacteria and fungi. The activity data shows that and cobalt complexes of DL-tryptophan are more potent than the DL-tryptophan.