TWISTED GRAIN-BOUNDARY PHASES IN 3 NEW CHIRAL AZOBENZENE SERIES

Three new chiral series with an azobenzene core have been synthesized and studied. The twist grain boundary smectic A and C phases, obtained with a cholesteric texture, were characterized by different technique s: binary diagram, racemic mixtures, helical pitch measurement and X-r ay diffraction. Helical pitch measurements of the TGB(A) and TGB(C) ph ases were performed using Grandjean-Cano wedges and those of the S-c phase with homeotropic drops. The pitch values are similar to those of tolane compounds previously studied. Electro-optical properties of th e S-c phase were measured with classical SSFLC geometry and the resul ts are comparable with previous studies.