Liquid Crystalline Properties of Mixtures Composed of N-[4-(Dimethylamino)phenyl]- and N-(4-Nitrophenyl)-α-(4-alkoxyphenyl) nitrones

Abstract

Abstract Nematic and smectic liquid crystals induced in binary mixtures of electron donors and acceptors of the type 4-X-C6H4-CH=NO-C6H4,-Y-4 (nitrones) and those of the type 4-X-C6H4-CH=N-C6H4-Y-4 (Schiff's bases) were compared. The terminal substituent X is a dimethylamino group in the donors and is a nitro group in the acceptors. The other terminal substituent Y is a methoxyl, ethoxyl, propoxyl or butoxyl group. The nematic liquid crystals induced by the compounds of the former type are as stable as those by the compounds of the latter type. Even though a smectic liquid crystal is more often observable when the central linkage is -CH=NO-, its thermal stability is, in general, not much affected by the modification. The following mixtures are exceptional; the donor carrying a butoxyl group with the acceptor carrying a propoxyl or butoxyl group. In these two cases, the maximum temperatures of the smectic liquid crystals induced in the nitrones are lower as much as 35 to 40°C than those induced in the corresponding Schiff's bases.