Observation of an anomalous SmA-SmC-SmA phase sequence in a bent-core liquid crystal derived from 4-cyanoresorcinol

The smectic phase with an anomalous dependence of the tilt angle on temperature for a bent-core liquid crystal is observed for the first time. In this phase, the tilt angle decreases on cooling and in the temperature range below the tilted phases, re-entrant orthogonal smectic phase (SmAPA) appears. At higher temperatures, a ferroelectric phase with a helix of short pitch is formed. As the tilt angle decreases on cooling, the helical phase transforms to a surface-stabilized (helixfree) flat anti-ferroelectric structure. This transition is explained by the out-of-plane biaxial anchoring energy