LIQUID-CRYSTAL FORMATION IN BINARY-SYSTEMS .10. POTENTIALLY SMECTOGENIC BEHAVIOR OF SOME PARA-DISUBSTITUTED BENZENES

Studies on binary systems with nematogenic N-(4-propoxybenzylidene)-4-hexylaniline revealed that 4-nitrophenyl alkanoates, alkyl 4-nitrobenzoates, N-(4-nitrophenyl)alkanamides, and N-alkyl-4-nitrobenzamides are potentially smectogenic. When the Schiff base is mixed separately with a homologous member from 4-nitrophenyl decanoate to tetradecanoate, a stable smectic A phase is induced and its maximum temperature is about 48 degree C. The estimated latent transition points to this mesophase of these benzene derivatives are in the range from minus 25 to 10 degree C. On the other hand, only metastable smectic A phases can be produced with hexyl to dodecyl 4-nitrobenzoates, the maximum temperatures being from 15 to 26 degree C. While the metastable smectic B phase of the Schiff base is to some extent stabilized by the addition of the alkanoates, it is drastically depressed by the benzoates.