Three electron-accepting dialkoxydicyanopyrazinoquinoxaline derivatives (1a, 1b, and 1c) showed properties of smectic (Sm) liquid crystals. Temperature-dependent X-ray diffraction studies were consistent with the formation of a bilayer structure through the π-overlap and interdigitation of alkoxy chains in the Sm liquid crystalline state. Intermolecular dipole-dipole interactions between the cyano groups played an important role in stabilizing the bilayer structure and liquid crystalline properties. Elongation of the alkoxy chains from C6H13O- (1a) and/or C12H25O- (1b) to C18H37O- (1c) changed the molecular arrangements and the liquid crystal phase from SmA to SmC, suggesting the importance of the van der Waals interaction of CnH2n+1O- chains for stabilizing the liquid crystalline phase. A hole-mobility value of 5 × 10-3 cm2 V-1 s-1 was observed for the SmA phase of 1b at 438 K based on transient photocurrent measurements.
ASJC Scopus subject areas
- Materials Chemistry