Synthesis of novel symmetrical tetra- and hexacatenar di-amides containing 1,3,4-thiadiazole units and a study of their mesomorphic and luminescence properties

Abstract

Novel tetra- and hexacatenar materials based on di-amides derived from 4-aminophenyl-1,3,4-thiadiazole derivatives have been synthesised (series 2a–f, 3a-f and 4a–f) and their mesomorphic properties have been studied by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction. All compounds in series 2a–f and 3a–f display an enantiotropic hexagonal columnar phase. With the exception of 4d and 4f, which are non-mesomorphic, all compounds in series 4a–f display enantiotropic hexagonal columnar mesomorphism. The mesomorphic properties were found to be dependent on the length, number of alkoxy chains attached at the end of the rigid core and on the nature of the central ring (benzene in series 2a–f, thiophene in series 3a–f and cyclohexane in series 4a–f). These compounds also show photoluminescence properties in the visible region. A thermogravimetric analysis was also performed.