Vibrational coupling as diagnostic for intramolecular hydrogen bonds of carbohydrates in aqueous solution

摘要

The coupling of vC-O and deltaO-D vibrations in the 1200-900 cm(-1) IR range leads to band shifting in opposite directions, which provides information on intramolecular hydrogen bonding of carbohydrates in aqueous solution. The aqueous solution IR spectra of 2-acetamide-1,6-anhydro-2-deoxy-D-glucopyranose and cis-1,2-cyclopentanediol and tetrahydrofuran-ethanol mixtures are reported. Frequency up-shifting upon deuteration is observed for the vC-O bands of both a hydrogen bond acceptor and donor in ether-hydroxyl and hydroxyl-hydroxyl contacts. The 1200-900 cm(-1) range can be used to reveal the presence of intramolecular hydrogen bonds in aqueous carbohydrates, unlike the OH stretching region, which cannot be used in this sense due to carbohydrate band masking by the strong vOH IR absorption of water. (C) 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 20-25, 2002; DOI 10.1002/bip. 10024. [References: 22]