Fluid Biaxial Banana Smectics: Symmetry at Work

Pii: S0020-7225(99)00110-x

We discuss the macroscopic properties of several classes of polar liquid crystalline phases. We focus on polar biaxial liquid crystalline phases made of achiral molecules with ̄uidity in two and three spatial dimensions. The classes we examine include polar biaxial nematic phases, orthogonal biaxial smectic phases with anisotropic in-plane ̄uidity and tilted polar biaxial smectic phases with in...

Evidence for triclinic symmetry in smectic liquid crystals of bent-shape molecules.

The first experimental evidence for triclinic symmetry of bulk smectic liquid-crystal samples of achiral banana-shaped molecules is presented. This phase corresponds to the so-called Sm-CG phase consisting of biaxial molecules and characterized by two tilt directions with respect to the layer normal: tilt of the molecular plane (clinic) and tilt of the molecular kink direction (leaning). Each s...

Low symmetry tetrahedral nematic liquid crystal phases: Ambidextrous chirality and ambidextrous helicity.

We discuss the symmetry properties as well as the dynamic behavior of various non-polar nematic liquid crystal phases with tetrahedral order. We concentrate on systems that show biaxial nematic order coexisting with octupolar (tetrahedral) order. Non-polar examples are phases with D2 and S4 symmetries, which can be characterized as biaxial nematics lacking inversion symmetry. It is this combina...

Biaxial Smectic Banana Phases

Poisson-bracket approach to the dynamics of bent-core molecules.

We generalize our previous work on the phase stability and hydrodynamic of polar liquid crystals possessing local uniaxial C infinity v symmetry to biaxial systems exhibiting local C2v symmetry. Our work is motivated by the recently discovered examples of thermotropic biaxial nematic liquid crystals comprising bent-core mesogens, whose molecular structure is characterized by a non-polar-body ax...