BLUE PHASES AND TWIST GRAIN-BOUNDARY PHASES (TGBA AND TGBC) IN A SERIES OF FLUORO-SUBSTITUTED CHIRAL TOLANE DERIVATIVES

A series of fluoro-substituted tolane derivatives: (R)-1-methylheptyl -fluoro-4-n-alkoxybenzoyloxy)tolane-4-carboxylates is reported. Some m embers of this series exhibit the phase sequence: Cr-SmC-TGBC-TGBA-BP I-BPII-BPIII-I. The blue phases, the TGBA and TGBC phases and the SmC phase were characterized in detail by microscopic observation, differ ential scanning calorimetry, helical pi ch measurements, X-ray structu ral analysis and electro-optical study. The blue phases directly next to the TGBA phase were shown to be a new type of blue phase exhibiting smectic ordering. A commensurate TGBC phase with constant number of s labs per pitch was observed.