CW THz Spectroscopy of Alanyl Valine and Valyl Alanine

摘要

CW THz spectroscopy has been used to investigate the lowest frequency vibrational modes of a pair of isostructural dipeptide nanotubes. THz spectra were obtained from 2 cm{sup}(-1) to 100 cm{sup}(-1) at 4.2 K for several different preparations of alanyl valine and valyl alanine, as a means of studying effects of cocrystallized solvent molecules on the spectra of these hydrophobic nanotubes. Removal of water or other solvent molecules from the flexible pores of the alanyl valine hydrophobic nanotubes resulted in shifts of a few cm{sup}(-1) in the apparent positions of some spectral features. For valyl alanine, spectral changes are even smaller, reflecting the lessened impact of hydrophobic interactions on the stronger h-bonding network of this dipeptide.