Abstract
Crystal structures have been determined for 4-octyloxybiphenyl-4-yl 4-methoxybenzoate (I), which has the phase sequence of crystal-nematic-isotropic, and 4-octyloxybiphenyl-4-yl 4-cyanobenzoate (II), which has the phase sequence of crystal-smecticA-menatic-isohopic. The crystal of I has an 'imbricated' structure, i.e., a half-and-half overlapping of molecules, while that of II has smectic-like bilayer structure, in which core moieties and alkyl chains aggregate separately. These different features are closely related to their mesophase behavior. It was also observed that in the crystal of I, molecular long axes are oriented in one direction, resulting in a polar structure, while in that of II, dipole moments are canceled in the bilayer structure.
