| Summary: | Liquid crystals have long dominated in the display devices, due to their large optical
anisotropies and ability to undergo electric-field induced switching. In particular,
liquid crystals containing azobenzene offers faster switching times than electric-field
induced switching. The synthesis of liquid crystals containing azobenzene and alkyl
chains as terminal groups is studied. The target compounds of ethyl-4-{ 4-
hexyloxyphenylazo )benzoate (compound 2), ethyl-4-{ 4-decyloxyphenylazo )benzoate
(compound 3), and ethyl-4-(4-hexadecyloxyphenylazo)benzoate (compound 4) were
prepared. These liquid crystals were prepared through several organic syntheses steps
which are diazonium coupling and Williamson ether synthesis reactions. The yield
obtained for all the compounds synthesized was in the range 70-80010. Infrared
spectroscopy was used to identify the functional groups of all the intermediates and
target compounds. IH NMR spectroscopy was carried out only for compound 2 in
order to confirm its molecular structure. The mesomorphic behaviours of the target
compounds were investigated using differential scanning calorimetry (DSC). The
DSC thermograms reveal that only compound 2 is a liquid crystalline molecule as it
exhibited mesophase. As for compounds 3 and 4, they are crystalline solids because
no mesophase was discovered. The transition temperatures of these compounds were
influenced by different lengths ofthe alkyl chains.
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