Liquid crystalline N-substituted-3,4-difluoropyrroles exhibiting large positive dielectric anisotropy

Abstract

A series of liquid crystalline 3,4-difluoropyrrole derivatives have been synthesized, and their dielectric anisotropy, birefringence, viscosity and phase sequences have been measured. This novel class of compounds showed extremely large dielectric anisotropy, exceeding that of 3,4,5-trifluorophenyl derivatives, induced by a combination of the C–F dipole moment and the electron-donating feature of the nitrogen atom in the 3,4-difluoropyrrole ring. Molecular modelling using molecular orbital calculations has been performed and the results compared with the experimentally evaluated physical properties.