Synthesis and liquid-crystalline properties of a homologous series of antiferroelectric liquid crystals and their respective racemates

New chiral, as well as racemic 1-methylalkyl terephthalidene-bis-aminocinnamates have been synthesized and their liquid-crystalline properties investigated. Generally, the chiral compounds possess the antiferroelectric S*o phase, whereas in the homologous series of racemates, the appearance of the So phase depends on the length of the alkyl chain. For racemic compounds derived from 2-alkanols with an odd number of carbon atoms, a So phase is generally observed. On the other hand when the number of carbon atoms is even, a Sc phase occurs. Moreover, in racemic 1-methylbutyl terephthalidene-bis-aminocinnamate, a Sc–So–Sc reentrant phase sequence has been established.