Mailman, Aaron, Wong, Joanne WL, Winter, Stephen M, Claridge, Robert CM, Robertson, Craig M 
ORCID: 0000-0002-4789-7607, Assoud, Abdeljalil, Yong, Wenjun, Steven, Eden, Dube, Paul A, Tse, John S et al (show 3 more authors)
(2017)
Fine Tuning the Performance of Multiorbital Radical Conductors by Substituent Effects.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 139 (4).
pp. 1625-1635.
Abstract
A critical feature of the electronic structure of oxobenzene-bridged bisdithiazolyl radicals 2 is the presence of a low-lying LUMO which, in the solid state, improves charge transport by providing additional degrees of freedom for electron transfer. The magnitude of this multiorbital effect can be fine-tuned by variations in the π-electron releasing/accepting nature of the basal ligand. Here we demonstrate that incorporation of a nitro group significantly stabilizes the LUMO, and hence lowers U<sub>eff</sub>, the effective Coulombic barrier to charge transfer. The effect is echoed, at the molecular level, in the observed trend in E<sub>cell</sub>, the electrochemical cell potential for 2 with R = F, H and NO<sub>2</sub>. The crystal structures of the MeCN and EtCN solvates of 2 with R = NO<sub>2</sub> have been determined. In the EtCN solvate the radicals are dimerized, but in the MeCN solvate the radicals form superimposed and evenly spaced π-stacked arrays. This highly 1D material displays Pauli-like temperature independent paramagnetic behavior, with χ<sub>TIP</sub> = 6 × 10<sup>-4</sup> emu mol<sup>-1</sup>, but its charge transport behavior, with σ<sub>RT</sub> near 0.04 S cm<sup>-1</sup> and E<sub>act</sub> = 0.05 eV, is more consistent with a Mott insulating ground state. High pressure crystallographic measurements confirm uniform compression of the π-stacked architecture with no phase change apparent up to 8 GPa. High pressure conductivity measurements indicate that the charge gap between the Mott insulator and metallic states can be closed near 6 GPa. These results are discussed in the light of DFT band structure calculations.
| Item Type: | Article |
|---|---|
| Depositing User: | Symplectic Admin |
| Date Deposited: | 07 May 2019 08:57 |
| Last Modified: | 19 Jan 2023 00:50 |
| DOI: | 10.1021/jacs.6b11779 |
| Open Access URL: | http://doi.org/10.1021/jacs.6b11779 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3040004 |
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