Crystal Structure of 4,4′-Biphenylene- Bis(Oxycarbonylbutyric Acid)

Abstract

4,4′-biphenylene-bis(oxycarbonylbutyric acid), C₂₂H₂₂O₈, a dicarboxylic acid containing a mesogenic core, has been synthesized and its crystal and molecular structure has been determined at room temperature by direct methods. Crystals are monoclinic, space group P2₁/c, a = 19.548(2)Å, b = 8.309(2) Å, c = 18.968(6) Å, ß = 99.24(2)°, with six molecules in the unit cell. The structure was refined by full matrix least squares method to R = 0.060 for 3285 observed independent reflections having I > 3σ(I). Molecules with two different conformations are present in the unit cell. The main conformational difference regards the dihedral angle between the planes of the phenyl rings in the biphenyl moiety, which is 0° in the centrosymmetric molecules and 25.0(3)° in the other molecules. Molecules are bonded along extended rows through hydrogen bonds between carboxylic groups. Centrosymmetric molecules form rows of linear symmetry ti, whereas rows of symmetry t1 are formed by the noncentrosymmetric molecules.