The synthesis and properties of a few dozen highly evolved analogues of (S)-MHPOBC are reported. The liquid crystal phases, and phase transition temperatures and enthalpies, as evidenced by polarized optical microscopy and differential scanning calorimetry, respectively, are given. The helical pitch in pure compounds and some mixtures is estimated using the selective reflection method. All of the compounds show antiferroelectric phases, and some key structure–property relationships for the new materials are reported. Specifically, it is found that the length of the oligomethylene segment of a novel partially fluorinated alkoxy ether tail incorporated into the structures strongly influences the stability of the antiferroelectric phase and the observed phase sequences, as well as the values of the helical pitch and its temperature dependence. The formulation of a family of broad temperature range eutectic mixtures possessing the highly desirable orthoconic antiferroelectric phases with long helical pitch is described.
The synthesis, mesomorphic properties and UV absorption spectra of laterally fluorine substituted, and the corresponding unsubstituted, 4′-alkyl-, 4′-alkoxy-, 4′-alkylcyclohexyl-, 4′-alkylbicyclo [2,2,2]octyl- and 4′-alkylcyclohexylethyl-4-isothiocyanatotolanes are described. Multicomponent broad range nematic mixtures with birefringence values higher than 0.4 and moderate viscosities are developed.
The molecular structures and physical properties of several single‐ and double‐fluorinated isothiocyanatotolane, isothiocyanatocyclohexyltolane, and isothiocyanatoterphenyl compounds are reported. Two eutectic mixtures comprising these compounds are formulated and their properties evaluated. These mixtures exhibit a high birefringence, relatively low viscosity, high resistivity, and good photo and thermal stabilities. Potential applications of these mixtures for spatial light modulators, optical phased arrays, and high speed photonics are discussed.
Molecular structures and their relation to the mesogenic behavior as well as physical parameters of orthoconic antiferroelectric smectic phases formed by partially fluorinated esters are reviewed. New multicomponent mixtures with long pitch and their electrooptical performance are demonstrated.
We have designed, synthesised and evaluated the physical properties of some high‐birefringence (Δn) isothiocyanato phenyl‐tolane liquid crystals. These compounds exhibit Δn ∼ 0.48–0.52 at room temperature and wavelength λ = 633 nm. Laterally substituted fluorine atoms eliminate smectic phases and lower the melting temperature. The moderate melting temperature and very high clearing temperature make those compounds attractive for eutectic mixture formulation.