The complexes of CoII, NiII, CuII and ZnII metal cations with tryptophan amino acid were synthesized and characterized by FT-IR, TG/DrTG-DTA, UV-Vis spectroscopy and elemental analysis methods. The complexes were synthesized with high purity. The results of the elemental analysis indicated that the complexes contain two molecules of tryptophan as monoanionic bis-chelated ligands per mole formula unit that are coordinated acidic oxygen κ-O and amine grops κ-N and two moles coordinated aqua ligands in CoII, NiII and ZnII complexes, the CuII has just one mole aqua ligand so its geometry is square pyramidal. The others have octahedral geometry.
Lastly biological activities of complexes were investigated as anti-bacterial, anti-microbial and anti-fungal. The synthesized metal complexes were tested for antimicrobial activity by disc diffusion method. The results of these studies show the metal complexes to be more antimicrobial against one or more species. Also, total antioxidant capacity of the metal complexes were determined that of Zn(II)-trp and Ni(II)-trp complexes were found higher than other complexes.