Twist-bend heliconical chiral nematic liquid crystal phase of an achiral rigid bent-core mesogen

The chiral, heliconical (twist-bend) nematic ground state is reported in an achiral, rigid, bent-core mesogen (UD68). Similar to the nematic twist-bend (N-TB) phase observed in bent molecular dimers, the N-TB phase of UD68 forms macroscopic, smecticlike focal-conic textures and exhibits nanoscale, periodic modulation with no associated modulation of the electron density, i.e., without a detectable lamellar x-ray reflection peak. The N-TB helical pitch is p(TB) similar to 14 nm. When an electric field is applied normal to the helix axis, a weak electroclinic effect is observed, revealing 50-mu m-scale left- and right-handed domains in a chiral conglomerate.