Abstract
Selenium (IV)-amino acid complexes: [Se(Orn)(2)(Cl)(2)] (1), Orn-Ornithine; [Se(Ile)(2)(Cl)(2)] (2), Ile-Isoleucine; [Se(Trp)(2)(Cl)(2)] (3), Trp-Tryptophan, and [Se(Arg)(2)(Cl)(2)] (4), Arg-Arginine were synthesized and well-characterized using a variety of analytical techniques such as elemental analysis, thermal analysis and (FT-IR, Raman laser, H-1-NMR, and UV-Vis) spectroscopy. Micro-analytical elemental analysis measurements confirmed that the 1:2 selenium ions: amino acid ratio was formed with a bidentate chelate. In the FT-IR spectra of the ligands, the nu(s)(N-H) stretching vibration of -NH2 group was shifted to lower wavenumbers after complexation. The nu(C=O) stretching vibrations of the carboxylic group are shifted in the spectra of complexes, which confirmed the involvement of the -COOH group in complexation. The selenium ions were six-coordinated with the geometry of the amino acid complexes. The nanostructure form of selenium was investigated by Raman laser spectroscopy, X-ray powder diffraction, and using a scanning electron microscope (SEM). The free radical scavenging activity of newly synthesized selenium (IV) complexes were determined at different concentrations of 10, 20, and 30 ppm based on their interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH).