Mixed Columnar Assembly of Ferroelectric and Antiferroelectric Benzene Derivatives Bearing Multiple -CONHCH Chains.

The discotic hexagonal columnar (Col) liquid crystalline phases of simple benzene derivatives bearing -CONHCH chains at the 1-, 3-, and 5-positions () and 1-, 2-, 4-, and 5-positions () display ferroelectricity and antiferroelectricity, respectively. The phase transition behavior, molecular assembly structures, dielectric response, and ferroelectric properties of their mixed crystals [()()] were evaluated to clarify the nanoscaling effect on the collective inversion of the one-dimensional (1D) N-H···O═ hydrogen bonding interaction observed in the () chain. A small quantity of doped into ( ≤ 0.03) maintained the ferroelectric polarization-electric field response (-) in the ()() chains, where the antiferroelectric molecules in the ferroelectric column act as a pinning potential site for dipole inversion. On the contrary, a relatively large amount of doping ( ≥ 0.1) forms a domain separation state between the hydrogen-bonded () and () columns, in which the ferroelectric - hysteresis completely disappeared. The correlation length for the appearance of ferroelectricity in the 1D column was estimated to be ∼40 nm in the Col liquid crystalline phase of .