A room-temperature heptazine core discotic liquid crystal |
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Authors: | Sayed Mir Sayed Lin-Lin Deng Bao-Ping Lin |
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Affiliation: | School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory for Science and Application of Molecular Ferroelectrics, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, Jiangsu Optoelectronic Functional Materials and Engineering Laboratory, Southeast University, Nanjing, China |
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Abstract: | Heptazine is the fundamental structural and functional unit of graphitic carbon nitrides and has a π-conjugated planar symmetry with semiconducting properties. Molecular self-assembly is one of the key factors to drive the electronic behaviour of π-conjugated organic molecules. To enhance the semiconductivity, heptazine is decorated at its active sites with 2,3,5-tris(dodecyloxy)aniline to get well-organised columnar packing. A novel heptazine-core room-temperature discotic liquid crystal (HDLC) with hexagonal columnar geometry is discovered. The molecular structure and mesomorphic properties of HDLC are investigated by 1H-NMR, 13C-NMR, IR, polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. Photophysical and electrochemical properties of HDLC are studied by UV–vis/fluorescence spectroscopy and cyclic voltammetry (CV), respectively. The energy band gap of HDLC estimated from CV at room temperature is 1.63 eV, which is much narrower than the previously reported band gap for heptazine derivatives. This decrease in the energy band can be attributed to the particular designing of HDLC for columnar packing. As a columnar liquid crystal providing a smooth path to the charge transport, HDLC with such a narrow energy band gap may find applications in organic electronics. |
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Keywords: | Heptazine discotic liquid crystals hexagonal columnar phase optical and electrochemical properties |
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