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, C17H12O4, 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 Å) 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.

Crystal structures of 1-hy-droxy-4-prop-yloxy-9,10-anthra-quinone and its acetyl derivative

1-Hy-droxy-4-prop-yloxy-9,10-anthra-quinone, C17H14O4, (I), and its acetyl derivative, 4-acet-yloxy-4-prop-yloxy-9,10-anthra-quinone, C19H16O5, (II), were synthesized from the commercially available dye quinizarin. In both compounds, the anthra-quinone frameworks are close to planarity. There is a large difference in the conformation of the prop-yloxy group; the mol-ecule of (I) adopts a gauche conformation [O-C-C-C = -64.4 (2)°], although the mol-ecule of (II) takes a trans-planar conformation (zigzag) [O-C-C-C = 176.1 (3)°]. In the mol-ecule of (I), there is an intra-molecular O-H⋯O hydrogen bond. In both crystals, the mol-ecules are linked by C-H ⋯O hydrogen bonds. A difference in the mol-ecular arrangements of (I) and (II) is found along the stacking directions.

Synthesis and crystal structures of two purpurin derivatives: 1,4-dihy-droxy-2-propoxyanthra-quinone and 2-but-oxy-1,4-di-hydroxy-anthra-quinone

The title compounds were obtained by deprotonation of 1,2,4-tri­hydroxy­anthra­quinone (purpurin) using sodium hydride followed by reaction with either 1-bromo­propane or 1-bromo­butane. The compounds were characterized by ¹H and ¹³C NMR and the structures determined using single-crystal X-ray diffraction.

The title compounds were obtained by deprotonation of 1,2,4-tri­hydroxy­anthra­quinone (purpurin) using sodium hydride followed by reaction with either 1-bromo­propane or 1-bromo­butane. 1,4-Dihy­droxy-2-propoxyanthra­quinone crystallizes as a 1:1 solvate from aceto­nitrile, C₁₇H₁₄O₅·CH₃CN. The anthra­quinone core of the mol­ecule is essentially planar and both hy­droxy groups participate in intra­molecular O—H⋯O (carbon­yl) hydrogen bonds. The propyl chain is angled slightly above the plane of the anthra­quinone moiety with a maximum deviation of 0.247 (2) Å above the plane for the terminal carbon atom. In contrast, 2-but­oxy-1,4-di­hydroxy­anthra­quinone, C₁₈H₁₆O₅, crystallizes from nitro­methane with two independent mol­ecules in the asymmetric unit. The anthra­quinone core of each independent mol­ecule is essentially planar and both hy­droxy groups on both mol­ecules participate in intra­molecular O—H⋯O(carbon­yl) hydrogen bonds. The butyl chain in one mol­ecule is also angled slightly above the plane of the anthra­quinone moiety, with a maximum deviation of 0.833 (5) Å above the plane for the terminal carbon atom. In contrast, the butyl group on the second mol­ecule is twisted out of the plane of the anthra­quinone core with a torsion angle of 65.1 (3)°, resulting in a maximum deviation of 1.631 (5) Å above the plane for the terminal carbon atom.