Designing bent-core nematogens towards biaxial nematic liquid crystals

The nematic phase occurring in bent-core (or banana-shaped) molecule systems is conducive to the occurrence of biaxial (Nb) phase due to the inherent biaxial molecular shape. The tendency of bent-core molecules to stabilise a layered (smectic) structure poses one of the difficulties in obtaining the thermotropic Nb phase. To investigate the factors favouring the formation of the nematic phase, a number of bent-core nematic liquid crystals derived from 1, 3-phenylene central bent motifs were synthesised. Results of an investigation into the influence of the nature and position of substitutions on the central core and two rigid arms as well as the type of linkage units on the occurrence and stability of the nematic phase reveal important structure–property relationships. Textural and X-ray diffraction measurements have helped us identify molecules with the potential of exhibiting the Nb phase.