Vibrational studies on disaccharide/H2O systems by inelastic neutron scattering, Raman, and IR Spectroscopy

Inelastic neutron scattering (INS), Raman scattering, and infrared spectroscopy experiments on pure water and on aqueous solutions of homologous disaccharides, such as trehalose and sucrose, are presented. Neutron spectra were collected by using the spectrometer MARI at the ISIS pulsed neutron source of the Rutheford Appleton Laboratory (Chilton, U.K.). The principal aim of this work is to analyze the structural modifications induced on water by trehalose and sucrose to look for different structural arrangements that can account for their different effectiveness as bioprotectors. Special emphasis was addressed to the intramolecular stretching and bending spectral contributions and to the intermolecular librational mode. A comparison of the INS spectra from pure water with those of homologous disaccharide/water mixtures showed the same peculiar behavior as found in Raman scattering, infrared spectroscopy, and computational results derived from density functional theory (DFT).