Esters that exhibit smectic F to isotropic liquid phase transitions.

A number of esters of the type, 4-n-alkanoyloxy 4'-n-octyloxbiphenyl have been synthesized, and shown to exhibit isotropic liquid to hexatic smectic F phase transitions on cooling. The natural texture of the smectic F phase characterized by this transition separates from the isotropic liquid in the form of spherelites which have a hexagonal cross of optical discontinuity centered in them. Previously synthesized materials in which the direction of the ester function is reversed exhibit orthogonal hexatic B rather than tiled hexatic phases. This behavior can be linked directly to the extent of polorization of the delocalized pi in the central aromatic core.