Two crystal forms of mesogenic bis(4′‐cyanobiphenyl‐4‐yl) butanedioate

The title compound, C₃₀H₂₀N₂O₄, exhibits a nematic phase in the wide temperature range between 498.5 and 538.6 K, in spite of the short linker moiety. Two crystal forms have been found. In both forms, the molecule is centrosymmetric. Form I has a planar biphenyl group, while form II has a twisted biphenyl group with a twist angle of 34.75 (6)°. The packing modes are also different. In form I the long molecular axes are tilted with respect to each other at about 30°, while in form II the long molecular axes have an almost parallel arrangement.