Manifestation of chiral asymmetry of ferroelectric liquid crystals induced by optically active dipole dopants in a linear electrooptic effect

The existence of eight combinations of absolute spatial configuration, helix handedness and handedness of director tilt has been shown for ferroelectric liquid crystals induced by optically active dipole dopants (optically active diesters of 4,4'-terphenyl dicarboxylic acid). As in the case of individual ferroelectrics alternation of the helix handedness is observed depending on absolute configuration of the C*-atom and its position relative to the rigid core of the molecule. However for these induced ferroelectric liquid crystals the helix handedness does not depend on the inductive effect of the substituent adjacent to the C* atom, e.g. the helix handedness of all the (S)-2-chlorine substituted materials coincides with that of the (S)-2-methyl-butyl derivative. Substitution of a chlorine atom by a cyano group followed by conversion of absolute spatial configuration of the C* atom results in the opposite helical sense. Thus asymmetric parameters of the induced ferroelectric liquid crystals helix handedness and the handedness of director tilt (or the sign of P_s) do not depend directly on the absolute configuration of C* atom and its position in a molecule. For the substances investigated within all of the temperature range of the induced smetic C* phase no reversal of the tilt direction handedness was observed.