Synthesis and physical properties of high birefringence phenylacetylene liquid crystals containing a cyclohexyl group

We have synthesized new phenylacetylene-based liquid crystals containing a cyclohexyl or cyclohexylethyl group and evaluated their physical properties in order to develop a range of materials having high value of birefringence. The cyclohexyl-containing compounds exhibited nematic behaviour near room temperature and moderate values of Deltan of around 0.3. The cyclohexylethyl-containing compounds had a very wide nematic range with a high T-NI and very high values of Deltan of over 0.4. They also exhibited low viscosities. The order parameter was not affected by introducing either a cyclohexyl or a cyclohexylethyl group and the values of Deltan based on calculated polarizabilities were obtained experimentally.