Acta Cryst. (2012). E68, o211 [ doi:10.1107/S1600536811053219 ]
Abstract: In the title molecule, C28H18O10, the two central benzene rings form a dihedral angle of 31.0 (1)°. In the phthalic acid fragments, the carboxy groups in the meta positions are approximately coplanar with the attached benzene rings, being inclined to their planes at 2.7 (1) and 10.3 (1)°, while the carboxy groups in the ortho positions are twisted from the benzene ring planes by 83.5 (1) and 75.4 (1)°. In the crystal, O-HO hydrogen bonds link the molecules into layers parallel to the bc plane. Weak C-HO hydrogen bonds and - interactions between the aromatic rings [centroid-centroid distance = 3.7674 (3) Å] further consolidate the crystal packing.
Online 21 December 2011
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