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Issue 3, 2017
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Facile transformation of 1-aryltriphenylenes into dibenzo[fg,op]tetracenes by intramolecular Scholl cyclodehydrogenation: synthesis, self-assembly, and charge carrier mobility of large π-extended discogens

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Abstract

The search for new organic semiconductors with enhanced charge transport properties and self-organizing abilities plays a pivotal role in the development of new applications in the emerging field of organic electronics. We have synthesized two series of discotic mesogenic materials derived from hexasubstituted triphenylene, including (i) 1-aryl-2,3,6,7,10,11-hexakis(pentyloxy)triphenylenes (14 new compounds) by a Suzuki cross-coupling reaction between the appropriate 1-bromotriphenylene precursor and various arylboronic acids and (ii) unsymmetrical facial dibenzo[fg,op]tetracene discotic molecules (11 new compounds) by an FeCl3-oxidized cyclodehydrogenation reaction of the former. The mesomorphism has been investigated by polarizing optical microscopy, differential scanning microscopy, and small-angle X-ray scattering. Most aryl-substituted triphenylene derivatives exhibit a single hexagonal columnar mesophase, enantiotropic over small temperature ranges or monotropic, with this low stability being likely attributed to the free-rotating bulky side-on arene group that disrupts a perfect stacking. The corresponding more rigid and flat dibenzo[fg,op]tetracene derivatives also self-organize into a hexagonal columnar mesophase, but with a larger mesophase stability than their parents, and occurring slightly above room temperature. The UV/vis absorption and fluorescence emission spectra have been measured. Tetracenes show stronger photoluminescence than aryltriphenylene in solution, while the reversed is observed in thin films, where a strong excimer emission for one of the polar 1-aryltriphenylenes is observed. The charge carrier mobility of two representative discogens has been measured by the time-of-flight photocurrent technique. The results show that the discogen with a lateral nucleus dipole displays a hole mobility of 10−4 cm2 V−1 s−1 in the mesophase, while the non-polar compound exhibits a hole mobility of 10−2 cm2 V−1 s−1 in its metastable-induced ordered phase. The charge carrier mobility is discussed as a function of the supramolecular organization.

Graphical abstract: Facile transformation of 1-aryltriphenylenes into dibenzo[fg,op]tetracenes by intramolecular Scholl cyclodehydrogenation: synthesis, self-assembly, and charge carrier mobility of large π-extended discogens

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Publication details

The article was received on 18 Oct 2016, accepted on 13 Dec 2016 and first published on 03 Jan 2017


Article type: Paper
DOI: 10.1039/C6TC04530H
J. Mater. Chem. C, 2017,5, 669-682

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    Facile transformation of 1-aryltriphenylenes into dibenzo[fg,op]tetracenes by intramolecular Scholl cyclodehydrogenation: synthesis, self-assembly, and charge carrier mobility of large π-extended discogens

    K. Zhao, M. Jing, L. An, J. Du, Y. Wang, P. Hu, B. Wang, H. Monobe, B. Heinrich and B. Donnio, J. Mater. Chem. C, 2017, 5, 669
    DOI: 10.1039/C6TC04530H

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