Abstract
Atomically precise single-layer graphene fragments show size- and edge-dependent electronic properties and are promising materials for electronics, photonics and spintronics. However, their synthesis has been limited to a few types of reactions. In addition, bilayer graphene fragments can exhibit intriguing properties originating from interlayer electronic interactions, but attaining a stable bilayer structure remains challenging. Here we report a synthetic strategy to prepare large-size single-layer graphene fragments by using intramolecular radical-mediated coupling reactions. One of the obtained open-shell graphene fragments demonstrates a closely stacked bilayer structure in solid state via strong intermolecular radical–radical interaction, which can be classified as delocalized ‘32-centre-2-electron’ pancake bonding. The bilayer structure is persistent in solution and dissociates only at highly oxidized states. The electronic properties of the graphene fragments were investigated. This study provides an intramolecular/intermolecular radical-mediated/radical–radical coupling approach towards diverse single-layer, bilayer and possibly multilayer graphene fragments with tunable properties.
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Data availability
The data that support the findings of this study are available in Supplementary Information. Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2220240 (dtbp-OR-2) and 2220242 (tips-OR-3). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Source data are provided with this paper.
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Acknowledgements
J.W. acknowledges the financial support from A*STAR AME IRG grant (A20E5c0089) and NRF Investigatorship award (NRF-NRFI05-2019-0005). Z.S. thanks the financial support from National Natural Science Foundation of China (21971187), Natural Science Foundation of Tianjin (19JCJQJC62700) and the Haihe Laboratory of Sustainable Chemical Transformations.
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T.J., Z.S. and J.W. conceived the project, designed the research and prepared the manuscript. T.J. carried out experiments and analysed the data. Z.S. and J.W. supervised the project. X.H., S.W. and X.M. contributed to X-ray crystallographic analyses. T.X. contributed to ESR measurements. L.R. contributed to oxidation titration analyses. Y.G. contributed to theoretical calculation of aromaticity. Y.N. discussed and commented on the manuscript.
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Nature Synthesis thanks Wei Zhang, Andrey Turchanin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary handling editor: Alison Stoddart, in collaboration with the Nature Synthesis team.
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Supplementary Information
General methods, Supplementary Figs. 1–109, Tables 1–14 and Cartesian coordinates for the optimized structures.
Supplementary Data 1
Crystal data for dtbp-OR-2, CCDC 2220240.
Supplementary Data 2
Crystal data for tips-OR-3, CCDC 2220242.
Source data
Source Data Fig. 5
VT ESR data.
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Jiao, T., Ni, Y., Xu, T. et al. Synthesis of monolayer and persistent bilayer graphene fragments by using a radical-mediated coupling approach. Nat. Synth 2, 1104–1115 (2023). https://doi.org/10.1038/s44160-023-00348-w
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DOI: https://doi.org/10.1038/s44160-023-00348-w
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