Bent Molecules with a 60° Central Core Angle that Form B7 and B2 Phases

Small-angle bent-core liquid-crystalline (LC) molecules based on a 1,2-bis(phenylethynyl)benzene central core have been synthesized that form banana smectic phases with a ferroelectric B7-antiferroelectric B2 phase sequence upon cooling. The formation of polar, switchable ferro-/antiferroelectric banana phases indicates that, despite the low core bend angle of approximately 60°, banana smectic phases are still formed with the bend direction parallel to the layer. This study offers significant evidence that shows bent-core molecules with a 60° bend angle can form the well-known B2 and B7 banana phases. Consequently, it may lead to the preparation of a wide variety of novel bent molecules with low bend angles that spontaneously form an LC phase with both polarization and chirality.