Two homologous series of antiferroelectric liquid crystals have been synthesized and their mesomorphic behaviour investigated by DSC and polarized light microscopy is presented. The mesogenic group consists of a biphenyloate-naphthoate unit, the varied terminal chain being attached to this via a six-membered alkyl chain, as long chains promote high tilt angles. The terminal chain is either alkanoyloxy alkoxy or perfluoroalkanoyloxy alkoxy. The behaviour of these series are discussed and compared to two previously reported analogous series which have a benzoate group in place of the naphthoate group, and which exhibit an orthoconic SmC*(A) phase. The naphthoate unit leads to an increase in transition temperatures and a slight decrease in the stability of the SmC*(A) phase whilst enhancing the SmC* and SmA phases.
- liquid crystal