Theoretical and Experimental Study of Spectroscopic Characteristics of Aromatic Amino Acids

Abstract

Photoluminescence spectra of aromatic amino acids, which are prepared in the form of microcrystalline powders and their aqueous solutions and are excited by laser radiation, are studied. Luminescence spectral regions and the maxima of luminescence intensity are determined. The spectral dependences of the molar extinction coefficients are measured for the aqueous solutions of amino acids. The electronic absorption spectra of aromatic amino acids and the charge distribution in the corresponding molecules are calculated, by using the quantumchemical Hartree-Fock method with the application of the semiempirical PM3 and ZINDO/S approximations. The electronic absorption spectra are analyzed. K e y w o r d s: aromatic amino acids, photoluminescence, absorption spectra, quantum transitions, HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), charge distribution.

Solubility ofdl-serine anddl-phenylalanine in aqueous mixtures of dimethyl sulfoxide and solvation thermodynamics

“…As the concentration of DMSO is increased, the association between H 2 O and DMSO (Scheme 2(A)) may occur 20,35 resulting comparatively larger associated solvent molecules. The self association (dimerisation) of DMSO (Scheme 2(B)) 29,34 occurs in the higher concentration of DMSO in the mixed solvent system.…”