Journal of International Scientific Publications

The linear-polarized spectroscopy (IRor Raman) of oriented colloids in nematic host coupled with advanced theoretical calculations are applied as a part of modern “combined approach“ for spectral and structural elucidation of small dipeptides. L-phenylalanyl-L-tyrosine (H-Phe-Tyr-OH) and the hydrochloride of L-alanyl-Lphenylalanine stabilized as monohydrate (H-Ala-Phe-OH.HCl.2H2O) are studied. The obtained information, especially for the characteristic IR-bands of amide C=O-NH fragments and out-of-plane vibrations of the aromatic residues provids a structural information about the configuration of amide O=C-NH group/s and corresponding amide planes in the peptide molecules, which are characterized with a large number of vibrations. In the aromatic peptides with more neighboring disposed amino acid, the typical π-repulsion leads to a limitations of the RHF or B3LYP methods. A good agrrement between theory and experimental geometry parameters is obtained, when the calculations are performed at RI-MP2 level of theoretical approximation and high basis set.