Chirality and polarity transfers between bent-core smectic liquid-crystal substances.

Liquid-crystal phases with both solid and liquid characteristics are unique, since they exhibit chirality on both molecular and mesoscopic levels under special circumstances. We have studied binary composites formed by mixing of a chiral dimer (B-Ch), in which a bent core is covalently linked to a promesogenic cholesterol unit through a flexible spacer, and an achiral bent-core mesogen having two vicinal fluorine atoms (B-2F). The pure materials show smectic phases featuring C2 symmetry. The dimer B-Ch displays conventional chiral smectic C (SmC*) phase with a chirality--induced polarization P(c) approximately 30 nC/cm2, whereas B-2F possesses synclinic and anticlinic antiferroelectric "banana" smectic (SmCP) phase with a relatively high-polarization (P(b)) value of about 900 nC/cm(2). Mixing these two materials we were able to measure P(c), and we have verified that the molecular chirality contributes to the polarization of banana phases only in synclinic configurations.