Temperature dependence of relaxation processes in network polymeric systems

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 48, No. 1, pp. 110–114, January, 1988.     

Calculation and analysis of the frequencies of normal vibrations of 2,3-Di-O-nitro-methyl-β-D-glucopyranoside

A calculation of the frequencies and forms of the normal vibrations of the 31-atom molecule 2,3-di-O-nitromethyl-β-D-glucopyranoside has been performed. Particular emphasis has been placed on the interpretation of the strongest bands in the spectrum of 2,3-di-O-nitro-methyl-β-D-glucopyranoside, which are due to vibrations of the nitrate groups. The present work has been reported at the IV International Congress of theoretically competent chemists, Jerusalem (Israel), July 7–12, 1996. B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 724–728, November–December, 1997.     

Use of a computer for mathematical analysis of composite vibrational spectra

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 3, pp. 523–531, September, 1989.     

IR spectrum of cellulose

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 2, pp. 301–306, August 1989.     

Investigation of isomerization pathways in monosaccharides. Computer modeling of the hybrid conformations of hexapyranose rings

The method of Wiberg and Boyd was used to determine the pathways for the interconversion of the 3,4-anhydropyranose ring in methyl-2,6-di-O-acetyl-3,4-anhydro--DL (6,6-²H₂) derivatives of talopyranoside (1) and galactopyranoside (2). Stationary points were found on the potential surface. The E₀+¹H₀ and⁰H_1def conformations are global minima in 1. Three local minima are found near the boat conformation B_2.5 and^2.5B. Two saddle points are also found near these conformations. The¹H₀ and⁰H_1def conformations are also global minima in 2. Only one local minimum and two saddle points were found, as in the case of 1, near the B_2.5 and^2.5B conformations. The interconversion barriers in 1 and 2 were calculated. The physical factors affecting the ring conformation in these compounds were discussed.Institute of Physics, Belarus Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 112–118, March–April, 1993.     

Hydrogen bonds in carbohydrates

We propose a method of hydrogen-bond effective quasi-harmonic potential matching for taking into account changes in the torsional energy of CCOH groups involving H bonds. Knowledge of the perturbation potential has enabled analytical calculation of changes in the torsion force constants of these groups explicitly taking into account their dependences on the structure of the hydrogen bridge and the crystal as a whole. It is also shown that the application of the matched potential for determining the torsion angle (CCOH group energy minimization in the cluster) leads to a better agreement with the experimental geometrical data.     

A theoretical study of vibrational spectra of tetranitrate-methyl-β-D-glucopyranoside and 2,3-di-O-nitro-methyl-β-D-glucopyranoside

Coupled calculations were carried out of normal vibration frequencies from the point of view of the valence-force field scheme and of absolute IR band intensities by the CNDO/2 method for the tetranitrate-methyl-β-D-glucopyranoside molecule. A good agreement was achieved with the experiments. Normal coordinate analysis was made for 2,3-di-O-nitro-methyl-β-D-glucopyranoside molecule with force constants obtained for the tetra-nitrate-methyl-β-D-glucopyranoside. Before proceeding to the calculation of the spectra of such complex molecules of nitrates of monosaccharides, a complete experimental and theoretical investigation was performed of the vibrational spectra of methylnitrate, which made it possible to determine the deficit of force constants for the calculations of the spectra of nitrosubstituted glucopyranosides. Detailed interpretations of the observable IR spectra of both the nitro-glucopyranosides compounds considered are given. The absorption spectra sensitivity to the spot of the nitrate group localization was discovered. Special attention was focused on analyzing the spectra of nitrates of saccharides for the characteristic split of the band due to the asymmetric stretching vibrations of the ONO₂ groups in the region of 1600–1700 cm⁻¹.     

Raman spegtroscopy of the structure of polysagcharide acetates

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 1, pp. 108–112, January, 1991.