AXIAL CHIRAL ALLENYLACETATES AS NOVEL FERROELECTRIC LIQUID-CRYSTALS

Liquid crystalline alkane-3,4-dienoates (allenylacetates) have been sy nthesized. Most compounds incorporate a heterocyclic 1,3,4-thiadiazole ring or a pyrimidine ring as a constituent of the rigid core. These a xial chiral allene derivatives were at first obtained as racemic mixtu res. Some of them were also synthesized in enantiomerically enriched f orm by enantioselective synthesis. The compounds were investigated by polarizing microscopy and by differential scanning calorimetry. The th ree-ring compounds exhibit broad regions of smectic C-phases. The opti cally active three-ring compounds show broad S-c-phases with moderate values of spontaneous polarization.