Redetermined structure of gossypol (P3 polymorph)

Abstract

An improved crystal structure of the title compound, C30H30O8(systematic name: 1,1′,6,6′,7,7′-hexahydroxy-5,5′-diisopropyl-3,3′-dimethyl[2,2′-binaphthalene]-8,8′-dicarbaldehyde), was determined based on modern CCD data. Compared to the previous structure [Talipovet al.(1985).Khim. Prirod. Soedin. (Chem. Nat. Prod.),6, 20–24], geometrical precision has been improved (typical C—C bond-distance s.u. = 0.002 Å in the present structure compared to 0.005 Å in the previous structure) and the locations of several H atoms have been corrected. The gossypol molecules are in the aldehyde tautomeric form and the dihedral angle between the naphthyl fragments is 80.42 (4)°. Four intramolecular O—H...O hydrogen bonds are formed. In the crystal, inversion dimers with graph-set motifR22(20) are formed by pairs of O—H...O hydrogen bonds; another pair of O—H...O hydrogen bonds with the same graph-set motif links the dimers into [001] chains. The packing of such chains in the crystal leads to the formation of channels (diameter = 5–8 Å) propagating in the [101] direction. The channels presumably contain highly disordered solvent molecules; their contribution to the scattering was removed with the SQUEEZE [Spek (2015).Acta Cryst. C71, 9–18] routine inPLATONand the stated molecular mass, densityetc., do not take them into account.