Novel supramolecular columnar liquid crystals based on thiosemicarbazides

Novel liquid crystal materials based on 3,4-di-n-alkoxybenzoylthiosemicarbazides (3a-h, n = 5-10, 12, 14) were synthesised. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Compound 3a did not show mesomorphic properties; 3b shows a monotropic hexagonal columnar (Col(h)) phase. Compounds 3c-h display an enantiotropic Col(h) phase. The mesomorphic properties were found to be dependent on the length of alkoxy side chains. In N,N-dimethylformamide solution, all the compounds displayed a room temperature emission with lambda(max) at 361-332 nm. A thermogravimetric analysis also was performed.