Evidence for different polymorphisms with and without an external electric field in a series of bent-shaped molecules.

Five fluid tilted mesophases are observed in a series of achiral banana-shaped compounds. The terminal chain length is the pertinent molecular parameter which induces the polymorphism change. All the phases, refer to tilted lamellar structure without in-plane order in the layers.

Switching of banana liquid crystal mesophases under field.

Taking advantage of the great number of bent-core or "banana" compounds synthesized and studied in the laboratory, we describe their behaviour under the application of an external electric field. If the field were a static one, we would work within the frame of an equilibrium phase diagram in a (field E, temperature T) space where some phases would be simple dielectrics and others ferroelectric ones with a macroscopic polarization, either spontaneous or induced by the field. In this paper, we deal with the basic responses of "banana" liquid crystals under the application of a low frequency (1 to 100 Hz) AC field.