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Issue 35, 2017
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Modelling charge transport of discotic liquid-crystalline triindoles: the role of peripheral substitution

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Abstract

We have performed a multiscale approach to study the influence of peripheral substitution in the semiconducting properties of discotic liquid-crystalline triindoles. Charge carrier mobility as high as 1.4 cm2 V−1 s−1 was experimentally reported for triindoles substituted with alkynyl chains on the periphery (Gómez-Lor et al. Angew. Chem., Int. Ed., 2011, 50, 7399–7402). In this work, our goal is to get a deeper understanding of both the molecular electronic structure and microscopic factors affecting the charge transport properties in triindoles as a function of the spacer group connecting the central cores with the external alkyl chains (i.e., alkyne or phenyl spacers groups). To this end, we first perform Quantum Mechanical (QM) calculations to assess how the peripheral substitution affects the electronic structure and the internal reorganization energy. Secondly, boxes of stacked molecules were built and relaxed through molecular dynamics to obtain realistic structures. Conformational analysis and calculations of transfer integrals for closed neighbours were performed. Our results show that the insertion of ethynyl spacers between the central aromatic core and the flexible peripheral chains results in lower reorganization energies and enhanced intermolecular order within the stacks with a preferred cofacial 60° staggered conformation, which would result in high charge-carrier mobilities in good agreement with the experimental data. This work allows a deeper understanding of charge carrier mobility in columnar phases, linking the structural order at the molecular level to the property of interest, i.e. the charge carrier mobility. We hope that this understanding will improve the design of systems at the supramolecular level aiming at obtaining a more defined conducting channel, higher mobility and smaller fluctuations within the column.

Graphical abstract: Modelling charge transport of discotic liquid-crystalline triindoles: the role of peripheral substitution

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Publication details

The article was received on 10 Jul 2017, accepted on 10 Aug 2017 and first published on 10 Aug 2017


Article type: Paper
DOI: 10.1039/C7CP04632D
Citation: Phys. Chem. Chem. Phys., 2017,19, 24202-24208
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    Modelling charge transport of discotic liquid-crystalline triindoles: the role of peripheral substitution

    R. Volpi, A. C. S. Camilo, D. A. D. S. Filho, J. T. L. Navarrete, B. Gómez-Lor, M. C. R. Delgado and M. Linares, Phys. Chem. Chem. Phys., 2017, 19, 24202
    DOI: 10.1039/C7CP04632D

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