Aromatic dipeptides and their salts-Solid-state linear-dichroic infrared (IR-LD) spectral analysis and ab initio calculations

Stereo-structural analysis and IR-bands assignment of the aromatic dipeptides l-tryrosyl-l-phenylalanine (Tyr-Phe), l-phenylalanyl-l-tyrosine (Phe-Tyr) and their hydrochloride salts have been carried out by means of IR-LD spectroscopy of oriented as nematic liquid crystal suspension solid samples. The experimental data are compared with known crystallographic ones and theoretical predicted geometries at RHF/ and UHF/6-31G**.