Crystal structure of methyl3- O- β- d-glucopyranosyl- β- d-glucopyranoside (methyl β- d-laminarabioside) monohydrate

Abstract

Crystals of methyl - β- d-glucopyranosyl- β- d-glucopyranoside (methyl β- d-laminarabioside) belongto the orthorhombic system, space group P2 12 12, with α =14.548(2), b = 24.252(7), c = 4.938(1) Å, and Z = 4. The crystal structure was solved by the direct method and refined by the full-matrix least-squares procedure to an R-value of 0.062 for 1099 observed reflections in the X-ray data. The molecular structure is similar to that of β- d-laminarabiose. The torsional angles around the glycosidic bonds are influenced by both the existence of an intramolecular hydrogen bond at O-4′O-5 and the exo-anomeric effect. In the nonreducing residue, the exocyelic O-5-C-5-C-6-O-6 and C-4-C-5-C-6-O-6 torsional angles are (+) gauche and trans, respectively, whereas the corresponding torsional angles in the reducing residue are (−) gauche and (+) gauche. One water molecule cocrystallizes with each disaccharide, and the crystal structure is stabilized mainly by intra- and inter-molecular hydrogen bonds involving water molecules.