New Switchable Smectic Phases In Banana-Shaped Compounds

A new series of achiral compounds with banana-shaped molecules ('E-n') has been synthesized and studied by the classical techniques (optical microscopy, differential scanning calorimetry, X-ray diffraction, miscibility studies and electro-optic investigations). The short homologues (E-7-E-10) give switchable smectic mesophases. Nevertheless their textures clearly differ from those of the B2 mesophase. In addition, the E-10 compound displays a smectic polymorphism involving a new bilayered structure.