Crystal structure and computational study of 1-hy-droxy-3,6,7-trimeth-oxy-2,8-bis-(3-methyl-but-2-en-1-yl)-9H-xanthen-9-one (fuscaxanthone C).

The title xanthone derivative, C26H30O6, extracted from the bark of Cratoxylum glaucum, adopts an almost planar fused ring system with a maximum deviation of 0.078 (1) Å. In the crystal, mol-ecules are linked into inversion dimers by pairwise C-H⋯O inter-actions. These dimers are further linked into chains by C-H⋯π and C-O⋯π inter-actions. Computational chemistry revealed that the overall stabilization energy of the packing is dominated by dispersion energy. The conformations of related xanthones are also surveyed.