Research Article: Methyl α-l-rhamnosyl-(1→2)[α-l-rhamnosyl-(1→3)]-α-l-rhamnoside penta­hydrate: synchrotron study

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.

Partial Text

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 ▶).




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