Optical studies of the nematic phase of an oxazole-derived bent-core liquid crystal

Various optical and dynamic light scattering studies have been conducted on the nematic phase of an oxazole-derived bent-core liquid crystal. At optical length scales and in the absence of applied fields, homogeneously aligned samples of this material, which has an oxazole heterocyclic ring in the central core, are found to behave more like a conventional straight-core nematic than a previously investigated ester-based class of bent-core molecules that have a benzene ring as the core linkage between the two arms of the bow-shaped molecule. In particular, the nematic refractive indices of the oxazole compound combine in the standard way [i.e., square root of ((2no2+ne2)/3)] to match the isotropic value throughout the nematic range, and the observed director fluctuation modes have relaxation rates comparable to those of the usual thermotropics. However, polarized light scattering data reveal evidence of weak biaxial fluctuations, and indications of electric-field-induced biaxiality are observed in the refractive index measurements.