X-ray structures of dilaterally substituted racemic nematogens containing a chiral centre in one of the lateral chains

A bifurcated and an open chain ( linear) can be introduced laterally into m esogens containing four rings in the main core. The racemic compounds give a narrow nematic range. The X-ray crystal structures of two isomeric compou nds show that the bifurcated chain is not aligned along the core as the lin ear one is. This unfavourable arrangement may be the cause of the deleterio us effect of the bifurcated chain on the nematic range.