Stable frustrated phases in chiral liquid crystals derived from optically active (R)- and (S)-3-ethylmercapto-2-methylpropionic acids

Highly optically pure (R)- and (S)-3-ethylmercapto-2-methylpropionic acids were synthesized by using optically active (D)- and (L)-2,10-camphorsultams as chiral auxiliaries, respectively. Their derivatives, (R)- and (S)-EMMPN mB (m = 6-12), were prepared for investigation. Microscopic texture observa tions demonstrated that the materials possess three stable frustrated phase s: BP, TGB(A)* and TGB(C)* phases. Interestingly, it was found that the N* phase behaves as an intermediary phase between BP and TGB(A)* phases in a r ather narrow temperature range (calc. 0.5-1.4 degreesC). A study of the rac emic mixture, (+/-)-EMMPNmB (m = 10), indicated that the chirality of the m olecule could suppress the formation of smectic phases in the heating proce ss. An increase of alkyl chain length favoured the formation of the TGB pha ses particularly, in accompaniment with a change of TGB phases from monotro pic to enantiotropic. Moderate maximum P-S values (calc. 14-19 nC cm(-2)) a nd apparent tilt angle (calc. 20 degrees) were obtained for the TGB(C)* pha se in a surface stabilized ferroelectric liquid crystal geometry.