Analysis of the Structure of Carbohydrates with use of the Regularized Deconvolution Method of Vibrational Spectra

Abstract

The infrared spectra of polysaccharides (amylose and cellulose) as well as of their constituent monosaccharides (α- and β- D-glucose) and the results of their deconvolution are presented. The number of bands separated upon deconvolution in the 1200-920 cm-1 spectral range exceeds the number of visualized absorption maxima in the room temperature spectra by a factor of more than two. It is shown that the results of deconvolution of the IR spectra of monosaccharides are in good agreement with the data of normal coordinate analysis of these compounds in the crystalline state. The manifestation in IR spectra of the investigated monosaccharides of factor group splitting of a number of nondegenerate fundamental vibrational modes of molecules in the crystalline state has been found. It has been shown that the glycosidic linkage formation in polysaccharides with 1→4 glycosidic linkage is characterized by the appearance of new absorption bands in the 1175-1140 cm-1 spectral range, as compared to the infrared spectra of their constituent monomers. In the 1000970 см-1 range, in the deconvolved IR spectrum of cellulose, absorption bands, which are not observed in the monomer spectrum, are separated. The number of bands in the above region remains unchanged for amylose, as compared to the spectrum of monomer α-D-glucose

Keywords

• Vibrational spectroscopy, factor-group splitting, glycosidic linkage, carbohydrates, deconvolution