Thermotropic biaxial nematic liquid crystals

We have synthesized liquid crystal (LC) mesogens based on a nonlinear oxadiazole unit that exhibit nematic phases near 200 degreesC. Polarized microscopy and conoscopy indicate that these LCs are biaxial nematics. Unambiguous and quantitative evidence for biaxiality is achieved using H-2 NMR spectroscopy. 2D powder spectra, obtained by rotating H-2-labeled samples about an axis perpendicular to the magnetic field at similar to200 Hz, yield phase biaxiality parameters of similar to0.1 when coupled with rigorous and proven simulations.