Novel bi- and ter-thiophenes exhibiting ferri- and antiferro-electric behaviour

Preliminary results of the synthesis and liquid crystalline properties of s uitably substituted bi- and ter-thiophene-based chiral esters, derived from the appropriate thiophene-based carboxylic acid and either (S)-4-(1-methyl heptyloxycarbonyl)phenol or (S)-1-methylheptyl-4'-hydroxybiphenyl-4-carboxy late are reported. The bithiophene ester comprising one phenyl ring exhibit s monotropic smectic A, smectic C* ferro-, ferri- and antiferro-electric ph ase types. Increasing the number of rings, either thienyl or phenyl, increa ses both the melting point and thermal stability. The four ring compounds e xhibit enantiotropic smectic A, smectic C* ferro-, ferri- and antiferro-ele ctric phases together with underlying unknown phase type (S-X). The identit y of the S-X phase is tentatively assigned as S-I* following free-standing film characterisation and miscibility study.