Study of the Molecular Dynamics in the TGBA and S*c Mesophases of the Liquid Crystal 18FBTCO1M7

We report the first study of1nolecular dynaInics in a TGBA Inesophase, by Ineans of proton NMR relaxation, in a liquid crystal coInpound that exhibits TGBA and Sl Inesophases. The relaxation dispersion detected in the S( phase is siInilar to those observed in previous studies on this phase of other compounds, using the saIne experimental technique. The Inolecular dynaInics in the TGBA phase is clearly different froIn the one detected in conventional SA Inesophases of chiral Inolecules. In fact, for low Larlnor frequencies the Ti values increase on decreasing the teInperature, while for higher frequencies an inverse behaviour is detected. Furthermore, the slope of Ti over the phase transition TGBA Sl depends on the frequency. An additional relaxation Inechanisln arising froIn the particular structure of the TGBA phase is introduced in this work to describe the observed differences.