Crystal structure of 4'-allyl-4,5,6,7,2',7'-hexa-chloro-fluorescein allyl ester unknown solvate

In the title compound, 4'-allyl-4,5,6,7,2',7'-hexa-chloro-fluorescein allyl ester {systematic name: prop-2-en-1-yl 2,3,4,5-tetra-chloro-6-[2,7-di-chloro-6-hy-droxy-3-oxo-4-(prop-2-en-1-yl)-3H-xanthen-9-yl]benzoate}, C₂₆H₁₄Cl₆O₅, accompanied by unknown solvate molecules, the dihedral angle between the xanthene ring system (r.m.s. deviation = 0.046 Å) and the penta-substituted benzene ring is 71.67 (9)°. Both allyl groups are disordered over two sets of sites in statistical ratios. The scattering contributions of the disordered solvent mol-ecules (both Ph₂O and CHCl₃, as identified by NMR) were removed with the PLATON SQUEEZE algorithm [Spek (2015 ▸). Acta Cryst. C71, 9-18]. In the crystal, tetra-meric supra-molecular aggregates linked by O-H⋯O hydrogen bonds occur; these further inter-act with neighboring aggregates through C-Cl⋯π inter-actions arising from the benzene rings, forming infinite two-dimensional sheets. Each C₆Cl₄ ring shifts in the direction perpendicular to the two-dimensional sheet, exhibiting a helical chain in which every C₆Cl₄ ring is utilized as both a donor and an acceptor of Cl⋯π contacts. Thus, these two-dimensional sheets pack in a helical fashion, constructing a three-dimensional network.