Infrared and raman spectroscopy of carbohydrates

Abstract A theoretical study of the normal modes of vibration for D -glucose has been made by normal coordinate analysis. The calculated modes for β- D -glucose are shown to be in good agreement with the observed infrared and Raman frequencies, and the computed potential-energy distribution is compatible with previous experimental band-assignments. Lines at 840 cm−1 for α- D -glucose and at 898 cm−1 for the β-form, which are sensitive to the anomeric configuration, are predicted to occur at 845 and 901 cm−1, respectively. These two modes have been found to be similar, consisting essentially of a C-1-H deformation coupled to a mixed CH2 vibration. The band in the 1150 cm−1 region, which is characteristic of pyranose sugars, is predicted to be a complex ring-mode in each case. Also, the modes that are dependent upon the crystal structure for amylose and cellulose and occur at approximately 1432, 1334, and 1263 cm−1 are described as complex vibrations involving CH2, C-O-H, and C-C-H motions.