A chiral material with a new phase sequence: Twist grain boundary smectic A phase—blue phases

A new phase sequence: twist grain boundary S_a phase to blue phases was observed in a chiral compound (R)- or (S)-1-methylheptyl 3'-fluoro-4'-(3'-fluoro-4'-octadecyloxybenzoyloxy)tolan-4-carboxylate. It is the first time that blue phases have been found to occur above the TGBA phase in the absence of a cholesteric phase. These phases were characterized by microscopic observation, differential scanning calorimetry, the contact method and study of the racemic system.