Ferroelectric, ferrielectric and antiferroelectric mesophases in compounds with a polybenzyloxycarbonyl mesogenic core

An Influence of a Single Fluorine Atom Position in the Molecular Rigid Core on Physical Properties of Orthoconic Antiferroelectric Liquid Crystal

“…The spontaneous polarization decreases at the higher degree when the fluorine is substituted close to the chiral center. The same effect was observed according to the chlorine substitution in the molecular core [20]. This is because the electro-accepting fluorine substitution and the induction of the electric charge close to the dipole moment of the carbonyl group (this one is located close to the chiral center and which is to a great extend responsible for the spontaneous polarization value).…”

The temperature and concentration dependence of helical pitch in the mixtures of antiferroelectric compounds with the opposite helical twist sense

“…The change of helix handedness may be observed also within a phase. For example, it was found that the helix changes the twist sense within SmC * α phase [13], SmC * β phase [12], SmC * γ phase [19] [20]. The same is also observed in SmC * A phase [18].…”

“…This is not always true, because there are known compounds showing helical sense inversion even in the nematic phase [29,30]. In compounds forming antiferroelectric and/or ferroelectric phases as well as different subphases, the change of helical sense is normal behaviour as soon as the inversion is observed crossing phase transition as well as within phases [14][15][16][17][18][19][20]. Still new compounds are being discovered to have inversion of the helical sense.…”

Interlayer Self-Diffusion and Structure of Chiral Smectic Phases Studied by 2H NMR Exchange Experiment

“…The X-ray scattering experiment gave the first direct structural evidence for distinct superlattice periodicities consisting of two layers in the SmC A / phase, three layers in the SmC Fi1 / phase, and four layers in the SmC Fi2 / phase, 9 while the Sm C R / phase is a short-pitch version of the SmC* phase. 17,18 The exact disposition of molecules is still not clear within the base unit of the SmC Fi1 / and SmC Fi2 / phases.…”

“…Both symmetry consideration and thermodynamic argument lead to the only possible disposition in the anticlinic phases (φ is a measure of the difference between the azimuthal angles for molecules in the two neighboring layers) shown in Figure 1a. 3,11,17 φ ) 0°corresponds to the "Ising model", 19 while φ ) 120°(SmC Fi1 / ) or φ ) 90°(SmC Fi2 / ) gives the "Clock model". 20 Rotational diffusion of molecules has been studied in chiral phases by using the deuteron spin relaxation method, 5,21 while translational diffusion of molecules is harder to observe because of the very low diffusion constant in these phases, especially in anticlinic phases, about 10 -13 to 10 -14 m 2 /s.…”