Crystal structure and Hirshfeld surface analysis of 3,4-di-hydro-2H-anthra[1,2-b][1,4]dioxepine-8,13-dione.

The title compound, C(17)H(12)O(4), was synthesized from the dye alizarin. The dihedral angle between the mean plane of the anthra-quinone ring system (r.m.s. deviation = 0.039†à ) and the dioxepine ring is 16.29†(8)°. In the crystal, the mol-ecules are linked by C-H⋯O hydrogen bonds, forming sheets lying parallel to the ab plane. The sheets are connected through π-π and C=O⋯π inter-actions to generate a three-dimensional supra-molecular network. Hirshfeld surface analysis was used to investigate inter-molecular inter-actions in the solid-state: the most important contributions are from H⋯H (43.0%), H⋯O/O⋯H (27%), H⋯C/C⋯H (13.8%) and C⋯C (12.4%) contacts.