Preparation and Properties of Chiral Paramagnetic Liquid Crystals Having an Organic Radical Component Exhibiting Nematic and/or Smectic Phases

Abstract

All-organic paramagnetic liquid crystals are of great interest regarding the possibility of reorientation of molecules by low applied magnetic fields. In addition, introduction of chirality to paramagnetic liquid crystals may give rise to ferroelectricity and thereby the cooperative effect between the magnetic and electric anisotropy. To develop chiral paramagnetic liquid crystals, several racemic and enantiomerically enriched nitroxide mesogens have been prepared. EPR spectroscopy indicates that the g values of the racemates showing only a nematic phase decrease after crystal-nematic phase transition upon heating; this should be ascribed to the reorientation of the LC molecules by the external magnetic field. Application of electric fields to the SmC* phases has induced spontaneous polarization bringing about ferroelectricity.