Received 15 November 2007
The title compound, C19H18O7, also known as chrysoobtusin, was isolated from Cassia tora L. (Leguminosae). The anthraquinone ring system is almost planar, the dihedral angle between the two benzene rings being 4.27 (4)°. The structure is stabilized by intra- and intermolecular O-HO and C-HO hydrogen bonds, and by weak - stacking interactions along the b axis, with a centroid-centroid distance between related benzene rings of 3.800 (4) Å.
Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2004); software used to prepare material for publication: SHELXTL.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2185 ).
The authors acknowledge the Ministry of Science and Technology of China (fund No. 2006BAD27B03) for financial support, and South China University of Technology and South China Normal University for supporting this work.
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