Some optically active liquid crystalline 1,3,4-thiadiazole derivatives
incorporating differently substituted allenic moieties providing an a
xis of chirality have been synthesized. The compounds were investigate
d by polarizing microscopy, by differential scanning calorimetry and b
y electrooptical investigation. Thereby a common ferroelectic behavior
was found in the case of two derivatives whereas a more complex S-C-
polymorphism was found in the case of the other derivatives. We propos
e the occurrence of an antiferroelectric, a ferrielectric and a ferroe
lectric phase.