Microwave-assisted facile synthesis of discotic liquid crystalline symmetrical donor–acceptor–donor triads

We report the synthesis and characterization of two series of novel triphenylene–anthraquinone-based symmetric discotic liquid crystalline trimers. These triads were prepared using microwave dielectric heating. Conventional heating under similar reaction conditions failed to produce desired products. To the best of our knowledge, these are the first donor–acceptor–donor triads in which all the three components represent discotic mesogenic moieties. Chemical structures of these discotic oligomers have been characterized by spectral techniques and elemental analysis. The thermotropic liquid crystalline properties of these donor–acceptor–donor triads were investigated by polarizing optical microscopy and differential scanning calorimetry. They exhibit a columnar mesophase over a wide range of temperature. The columnar hexagonal mesophase structure of these discotic oligomers has been elucidated with the help of X-ray diffraction studies.