AN INVESTIGATION OF THE VIBRATIONAL-SPECTRA OF GLUCOSE, GALACTOSE AND MANNOSE

Infrared and Raman spectra have been obtained for the following compounds: α-glucose, α-glucose-1-d, α-glucose-6,6-d2, α-glucose-O-d5, δ-glucose, β-glucose-6,6-d2, β-glucose-O-d5, α-galactose, β-galactose, α-mannose and β-mannose. Many of these spectra have not been reported previously and others are better resolved than in older publications because the samples were maintained near liquid nitrogen temperature. A modified valence force field has been developed to give a least squares agreement between the observed and calculated frequencies for the various isotopic glucoses. This field also gives a satisfactory prediction of the mannose and galactose spectra. Overall, the average fit between 554 assigned and calculated frequencies is 6.86 cm-1 with 515 degrees of freedom. The forms of the normal modes calculated for these sugars are discussed and compared to the calculations of others for various carbohydrates. The results also provide insight into some older assignments of the group frequency type including anomeric correlations, "ring" modes and the controversial bands found near 1150 cm-1 in many carbohydrates. © 1990.