A new liquid crystal phase, the biaxial nematic (N<sub>b</sub>) phase, was discovered in oxadiazole based bent core compounds in 2004. Interest in this phase is due to the possibility of faster response times in display applications. However, in the original compounds, high transition temperatures to the nematic phase made these compounds impractical for use in liquid crystal displays (LCDs). Previous studies in the Scharrer lab showed that lowering the temperature range of the nematic phase was possible by adding lateral groups to the bent cores. Trisubstituted compounds showed lower transition temperatures and allowed the nematic phase to remain present to room temperature upon cooling. In an effort to further lower transition temperatures, tetramethylated compounds were prepared and found to have lower transition temperatures, though no liquid crystalline phase was seen on heating.  In addition, the nematic phase observed on cooling was less stable than for the trisubstituted compounds. This was attributed to more facile molecular packing. Our current efforts are focused on the preparation of asymmetric tetrasubstituted derivatives as the lack of symmetry may allow for the nematic phase to persist to lower temperatures.  Details of our synthetic efforts and phase behavior will be discussed.

Efforts to lower phase transition temperatures in asymmetrically substituted oxadiazole containing liquid crystals

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.