Ferroelectric liquid-crystalline compounds containing a sulfinyl group as unique source of chirality: Asymmetric synthesis and mesomorphic properties
- Institute de Physique et Chimie des Materiaux de Strasbourg (France)
The synthesis and mesomorphism of a series of new ferroelectric liquid crystals containing a sulfinyl group as the unique chiral center are described. This chiral center was introduced in the optically active form into the mesogenic molecules via the asymmetric synthesis of sulfinamide, sulfoxide, and sulfinate functional groups, directly connected to the aromatic rigid core. The role of the sulfinyl group nature, of the aromatic rigid core structure, of the chiral center position and of the alkyl chain length on the liquid-crystalline behavior have been investigated systematically. A central rigid core are not in favor of the occurrence of the mesomorphic character. On the contrary, sulfinates at the end of the core give a smectic C phase, stable within a reasonable temperature range. On the other hand, the only change of the sulfinyl group has large effects on the thermal stability of the mesophases, on the transition temperatures and more deeply on the polymorphic nature. This change leads to thermal instability with the sulfoxide compounds and with some sulfinamide ones, whereas the sulfinate mesogens are perfectly stable from both optical and thermal points of view. Thermal smectic C and A phases have been systematically studied as a function of aliphatic chain lengths. The alkyl chain of the sulfinate group plays a predominant role. Smectic A phases are favored when this chain is short, whereas smectic C phases are favored for long chains. The thermal stability of the smectic C mesophase is strongly correlated to the tilt angle of the molecules inside the smectic layers. 25 refs., 23 figs., 14 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 98748
- Journal Information:
- Chemistry of Materials, Vol. 6, Issue 11; Other Information: PBD: Nov 1994
- Country of Publication:
- United States
- Language:
- English
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