Novel chiral two ring compounds possessing phenylethenoate moieties were synthesized and their liquid crystalline properties determined. Some of these compounds were found to exhibit SmC*γ, AF and SmC*A phases, whereas in other compounds only SmA* and SmC* phases appear. The influence of the molecular structure on the appearance of SmC*γ, AF and SmC*A phases is discussed. The basic electro-optical properties of the homologous series of (S)-(E)4-(1-methylheptyloxycarbonyl)phenyl 4-alkoxycinnamates, in which SmC*, SmC*γ, AF and SmC* A phases appear, were also investigated. High values of spontaneous polarization, low threshold voltages and fast switching times at room temperature were observed.

We have synthesized a number of new achiral and chiral triphenylene derivatives bearing laterally substituted phenylene units in the side chains. Their polymorphism includes the first reported discotic blue phase of a pure compound and a ferroelectrically switchable columnar mesophase.

In an attempt to determine the physical nature of the low-frequency dielectric mode in antiferroelectric liquid crystals, we have studied the dielectric response in thick planar-oriented samples of Smectic C-A* compounds undergoing a helix inversion. If the mode is collective there ought to be a minimum in the dielectric absorption due to the mode, at the temperature at which the helical pitch diverges. Although the effect is not large, we find minima for both antiferroelectric modes at this point, indicating that both modes are related to the helical director structure. A corresponding experiment has also been performed on a binary mixture which shows a helix inversion for a certain mixing ratio. However, because the effect in this case is overshadowed by unavoidable variations in other parameters, no minimum was detected.

Liquid crystals are of major technological importance for display devices, as well as being of fundamental molecular interest. Understanding how their building-block molecules arrange themselves is critical for obtaining improvements in performance. In their research commentary, Heppke and Moro discuss recent findings about how the chirality, or handedness, of the underlying molecules influences the behavior of liquid crystals.

We have observed an acousticlike and an opticlike branch of phase excitations in a quasielastic light-scattering experiment performed in the antiferroelectric smectic-C-A* phase of 4-(1-ethylheptyloxycarbonyl)phenyl-4'-alkylcarbonyloxy biphenyl-4-carboxylate. In contrast to the nearly gapless acoustic phason branch, the opticlike phase excitations always have a finite relaxation rate. The phenomenon is a direct consequence of a doubling of a smectic unit cell at the transition from the smectic-A phase and is in remarkable agreement with a Landau-type model.

Dielectric measurements of a homologous series MHPnCBC exhibiting different phase sequences have been carried out. The results and the comparison with the theoretical predictions of the phenomenological model are presented for the dielectric behaviour in the smectic C-alpha* phase.