Establishment of phase diagram of a chiral smectic liquid crystal

Chiral smectic liquid crystals are well known to exhibit the following sequence of phases as the temperature is increased: Sm-C*(A), Sm-C*(Fi1), Sm-Cn(Fi2), Sm-C* and Sm-C*(alpha). Surprisingly, some compounds appear in several publications to present other tilted phases, which not only do not belong to the previous series but change from one paper to the other although the studied compound is the same. Such is the chiral smectic liquid crystal (R) or (S)-12OF1M7 that we have re-synthesized and studied with various techniques: dielectric spectroscopy, optical rotatory power, conoscopic measurements and electro-optic properties. Our conclusion is that this compound presents the ordinary phase sequence at the exception of the Sm-C*(alpha) phase. In addition, the (E-T) phase diagram of this compound was established. (C) 2011 Elsevier B.V. All rights reserved.