Functionalization of discotic liquid crystals by direct substitution into the discogen ring α-nitration of triphenylene-based discogens

It is demonstrated for the first time that discotic liquid crystals can be functionalized by direct substitution into the central ring (core) of the discogen. It is shown that hexahexyloxy-triphenylene (HAT6) can be easily nitrated to give the mono-α-nitrated product exclusively. This material, which has a discotic mesophase range between room temperature and 136°C, can be modified to give α-amino-, α-acetylamino- and α,α'-diazo-HAT6. These new materials all show enantiotropic mesophases, have permanent dipole moments and some of them are coloured. This generally applicable approach opens up a route to an enormous range of new discotic liquid crystals.