Fourier transform IR and Raman spectroscopy and structure of carbohydrates

To determine the role of the skeletal base configuration of carbohydrate molecules, a comparative study was made, using IR and Raman spectroscopy, of theoretical calculations of the vibrational spectra of a series of carbohydrates differing in the configuration of CO (CH) bonds in various positions of the pyranose ring. The normal vibrations of carbohydrate molecules have, with few exceptions, close or coinciding frequencies; however, they differ greatly in the shape and contribution to the potential energy distribution (PED) of individual groups and bonds. Despite the cooperative character of the vibrations, each compound is characterized by a specific set of frequencies with a prevailing contribution to the PED of particular CO and CC bonds of the molecule. It is concluded that vibrations have a peculiar localization and that steric factors play an important role in the vibrational spectra of carbohydrates. (C) 1997 Elsevier Science B.V.