Zhidong Chang

3,3'-[Biphenyl-4,4'-diylbis(-oxy)]diphthalic acid.

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—H⋯O hydrogen bonds link the molecules into layers parallel to the bc plane. Weak C—H⋯O hydrogen bonds and π–π interactions between the aromatic rings [centroid–centroid distance = 3.7674 (3) Å] further consolidate the crystal packing.