Fluid biaxial banana phases: Symmetry at work

Fluid biaxial smectics made from compounds without asymmetric carbons but nevertheless with a spontaneous polarization are now known as banana smectics because of their molecular shape. Here we show that symmetry changes under parity (r ← - r) are an efficient way to summarize and differentiate their electro-optic properties. Typical of fluid biaxial smectics, there are also a large number of stacking options endowing them with opto-electric properties spanning a broad range of economically viable applications. "Value-added features" of some banana smectics include a faster electro-optic response than found in liquid crystals with a helix structure, their steric property allowing rotations about an axis in a layer plane without compromising smectic layer stability and ambidextrous chirality.