[THz absorption spectra of several carbohydrate derivatives]

Intermolecular hydrogen bond vibrations may be observed in the THz range. Carbohydrates are important bio-molecules, and are the typical systems for the study of hydrogen bonds. Carbohydrate derivatives have critical biological functions, and there are extensive hydrogen bond networks in molecular system, therefore, they would have various bands in the THz region. The THz absorption spectra of several carbohydrate derivatives were measured using a THz apparatus at room temperature. The THz bands are as follows: 1.17, 1.35, 1.93 and 2.23 THz for isopropyl-beta-D-thioglucopyranoside; 1.93 THz for isopropyl-beta-D- thiogalactopyranoside; 1.87 THz for methyl-(tetra-O-acetyl-beta-D-galactopyranoside); 1.23, 1.70, 1.84 and 2. 23 THz for O-(2, 3, 4, 6-tetra-O-acetyl-beta-glucopyranosyl)-N-hydroxysuccinimide. The results indicate that different samples have various bands that originated from collective modes of the whole molecules and especially isomers can be distinguished, showing that THz method is sensitive to the molecular structures and spatial configurations and is a helpful complement of IR spectroscopy.