Solution behavior of methyl beta-xylobioside: conformational flexibility revealed by n.m.r. measurements and theoretical calculations.

The conformations of methyl beta-xylobioside in solution have been determined by n.m.r. spectroscopy. Interglycosidic 3JC,H values and the chemical shifts of the 13C resonances were measured at various temperatures in the range 238-378 K for solutions in 1,4-dioxane, methanol, methyl sulfoxide, and water. The temperature and solvent dependencies of the data obtained suggest conformational flexibility. Quantum-chemical PCILO calculations, with evaluation of the solvent effects, and molecular mechanics calculations revealed the existence of 7 low-energy regions for which the geometries and energies were determined. The computed abundances of conformers and averaged J values accord with the experimental data.