Novel mesomorphic phase transitions of symmetric dimeric alpha,omega-bis(4'-alkoxy-phenylbenzyl-4-ylthio) perfluoroalkane compounds

Symmetric dimeric liquid crystals, alpha,omega -bis(4-alkoxy-phenylbenzyl-4 -ylthio) perfluoroalkanes (nBFxBn), were newly synthesized and the mesomorp hic phase transitions were investigated. The phase transition behaviours ex hibited a dramatic dependence on the lengths of the two mesogenic groups an d the fluoroalkyl spacer of the central part. These compounds showed layere d mesophases like SmA, SmB and CrE, but it is noticable that twist grain bo undary smectic A (TGBA) phase is found in non-chiral 2BF6B2 and 3BF6B3 comp ounds, which up to now is only found in chiral liquid crystal compounds.