Oxazole-Based Liquid Crystals With Low Temperature Nematic Phases

This paper describes the synthesis and phase behavior of new oxazole containing liquid crystals. These compounds are related to oxadiazole derivatives which show a cybotactic nematic phase. The compounds described here possess a lateral bromo or chloro substituent and, in some cases, lateral methyl groups as well. Derivatives without lateral methyl groups exhibit enantiotropic behavior, while derivatives with lateral methyl groups show only monotropic behavior. However, several of the latter compounds supercool to room temperature in the nematic phase. In addition, the nematic phase of these derivatives retain fluidity to much lower temperatures than was observed for the oxadiazole analogs.