Calculation of absorption band frequencies and intensities in the IR spectrum of α-d-glucose in a cluster

Theoretical interpretation of spectral signs of an oxymethyl group in the IR spectrum of methyl-β-D-glucopyranoside

“…The band intensities match when comparing the theoretical and experimental spectra of methyl-β-D-glucopyranoside, analogous to the situation for unsubstituted monosaccharides [12,14,15]: extensive sections of the compared spectra are close or match in the ranges 1500-1200 cm -1 and 1200-1050 cm -1 . The theoretical spectrum in the 1050-950 cm -1 range has weaker intensity than the experimental spectrum, but the general character of the observed spectrum in this interval and the ratio of the integrated intensities of the bands making up the spectrum are reproduced by the calculation.…”

“…On going from the quasi-isolated molecule approximation to the cluster structural model of the molecule in a real crystalline environment, the intensities of the vibrations in the 3600-3000 cm -1 region, as shown previously in [12], increase by two orders of magnitude. This result is consistent with the known fact that the intensities of OH stretching vibrations are enhanced when hydrogen bonds including hydroxyl groups are formed [30].…”

“…The quasi-isolated molecule model was selected based on the conclusions of [6,12] from a study (within a cluster model and the quasi-isolated molecule model) of the effect of intermolecular hydrogen bonds in crystalline monosaccharides on the electronic structure of the molecules and the intensities of the absorption bands. It was shown in those studies that for interpretation of the spectral interval 3000-600 cm -1 , we can limit ourselves to the quasi-isolated molecule approximation in calculations of the IR spectra of monosaccharides.…”

“…for different organic compounds. These programs have been used to carry out a full theoretical analysis of the frequencies and intensities and a detailed interpretation of the IR spectra for a number of monosaccharides and selectively substituted monosaccharide nitrates [10][11][12][13][14][15][16][17][18][19][20].…”

Analysis of glucopyranoside trinitrate IR spectrum

“…The QIM model is the isolated molecule in the force field of which intermolecular interaction is considered indirectly through force constants without accounting for its influence on the electronic structure in calculating the vibration intensities. It has been shown [19] that interpretation of the spectral range 3000-600 cm -1 can be limited to this model in calculations of the IR spectra of monosaccharides.…”