Ferro-, ferri- and antiferro-electric behaviour in a bent-shaped mesogen

The synthesis of a novel bent-shaped, four-ring thiophene-based chiral liqu id crystalline ester derived from 5-(4-n-decyloxyphenyl)thiophene-2-carboxy lic acid and (S)-1-methylheptyl 4'-hydroxybiphenyl-4-carboxylate is reporte d, i.e., (S)-4'-(1-methylheptyloxycarbonyl)biphenyl-4-yl 5-(4-n-decyloxyphe nyl)thiophene-2-carboxylate. Optical microscopy, differential scanning calo rimetry, miscibility study, and complementary electro-optical and current r esponse studies reveal the existence of the SmA*, SmC*ferroelectric, SmC*fe rrielectric, SmC*antiferroelectric and SmI*antiferroelectric phase types. A nother mesophase type possibly exists below SmI*antiferroelectric which gen erates a rapid electro-optic response. Comparison with the analogous three- ring compound, i.e., (S)-4-(1-methylheptyloxycarbonyl)phenyl 5-(4-n-decylox yphenyl)thiophene-2-carboxylate increases the thermal stability by 95.8 deg rees C and the SmI*antiferroelectric phase is observed in addition.