Date Published: July 01, 2012
Publisher: International Union of Crystallography
Author(s): Lars Eriksson, Göran Widmalm.
The title hydrate, C19H34O13·5H2O, contains a vicinally disubstituted trisaccharide in which the two terminal rhamnosyl sugar groups are positioned adjacent to each other. The conformation of the trisaccharide is described by the glycosidic torsion angles ϕ2 = 48 (1)°, ψ2 = −29 (1)°, ϕ3 = 44 (1)° and ψ3 = 4 (1)°, whereas the ψ2 torsion angle represents a conformation from the major state in solution, the ψ3 torsion angle conformation may have been caught near a potential energy saddle-point when compared to its solution structure, in which at least two but probably three conformational states are populated. Extensive intermolecular O—H⋯O hydrogen bonding is present in the crystal and a water-containing channel is formed along the b-axis direction.
For a description of l-rhamnose as part of polysaccharides, see: Marie et al. (1998 ▶); Perry & MacLean (2000 ▶). For a description of the conformational dynamics of the title trisaccharide, see: Eklund et al. (2005 ▶); Jonsson et al. (2011 ▶). For a description of the puckering analysis of the residues, see: Cremer & Pople (1975 ▶). For further background to l-rhamnose, see: Ansaruzzaman et al. (1996 ▶); Varki et al. (1999) ▶; Kulber-Kielb et al. (2007 ▶); Lindberg (1998 ▶); Säwén et al. (2010 ▶).