title: Field-induced phase transitions and reversible field-induced inversion of chirality in tilted smectic phases of bent-core mesogens.
abstract: Three homologous achiral five-ring bent-core mesogens are presented where 4-chlororesorcinol is the central core and the aromatic rings are linked by ester groups. These compounds form smectic phases with a tilted arrangement of the molecules (tilt angle approximately 45 degrees). On cooling the isotropic liquid this phase adopts a fan-like texture which shows for two homologues at relatively high electric fields ( 25-35 V microm(-1)) an antiferroelectric electro-optical response based on the collective rotation of the molecules around their long axes. At lower temperature the application of a sufficiently high electric field leads to a continuous transition into a non-birefringent texture which exhibits randomly distributed domains of opposite handedness. These domains can be reversibly switched into a state of opposite chirality by reversal of the field polarity. This switching is bistable and shows a current response typical for a ferroelectric ground state. The possible mechanism of the field-induced phase transition, of the ferroelectric switching and of the field-induced inversion of the chirality is discussed on the base of XRD, 13C- and 1H-NMR investigations, dielectric and electro-optical measurements.
authors.affiliation: Institut für Physikalische Chemie, Martin-Luther-Universität Halle-Wittenberg, Mühlpforte 1, 06108, Halle (Saale), Germany.
authors.forename: G
authors.initials: G
authors.lastname: Pelzl
authors.forename: M W
authors.initials: MW
authors.lastname: Schröder
authors.forename: A
authors.initials: A
authors.lastname: Eremin
authors.forename: S
authors.initials: S
authors.lastname: Diele
authors.forename: B
authors.initials: B
authors.lastname: Das
authors.forename: S
authors.initials: S
authors.lastname: Grande
authors.forename: H
authors.initials: H
authors.lastname: Kresse
authors.forename: W
authors.initials: W
authors.lastname: Weissflog