Carbon nanostructures with zigzag edges exhibit unique properties—such as localized electronic states and spins—with exciting potential applications. Such nanostructures however are generally synthesized under vacuum because their zigzag edges are unstable under ambient conditions: a barrier that must be surmounted to achieve their scalable integration into devices for practical purposes. Here we show two chemical protection/deprotection strategies, demonstrated on labile, air-sensitive chiral graphene nanoribbons. Upon hydrogenation, the chiral graphene nanoribbons survive exposure to air, after which they are easily converted back to their original structure by annealing. We also approach the problem from another angle by synthesizing a form of the chiral graphene nanoribbons that is functionalized with ketone side groups. This oxidized form is chemically stable and can be converted to the pristine hydrocarbon form by hydrogenation and annealing. In both cases, the deprotected chiral graphene nanoribbons regain electronic properties similar to those of the pristine nanoribbons. We believe both approaches may be extended to other graphene nanoribbons and carbon-based nanostructures.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to Nature and 55 other Nature journal
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
All relevant data generated and analysed during this study, including STM and scanning tunnelling spectroscopy data and theoretical calculations, are included in this Article and its Supplementary Information and are also available from the authors upon reasonable request. Source data are provided with this paper.
Corso, M., Carbonell-Sanromà, E. & de Oteyza, D. G. in On-Surface Synthesis II 113–152 (Springer, 2018).
Yano, Y., Mitoma, N., Ito, H. & Itami, K. A quest for structurally uniform graphene nanoribbons: synthesis, properties, and applications. J. Org. Chem. 85, 4–33 (2020).
Zhou, X. & Yu, G. Modified engineering of graphene nanoribbons prepared via on‐surface synthesis. Adv. Mater. 32, 1905957 (2020).
Chen, Y.-C. et al. Molecular bandgap engineering of bottom-up synthesized graphene nanoribbon heterojunctions. Nat. Nanotechnol. 10, 156–160 (2015).
Rizzo, D. J. et al. Topological band engineering of graphene nanoribbons. Nature 560, 204–208 (2018).
Gröning, O. et al. Engineering of robust topological quantum phases in graphene nanoribbons. Nature 560, 209–213 (2018).
Li, J. et al. Survival of spin state in magnetic porphyrins contacted by graphene nanoribbons. Sci. Adv. 4, eaaq0582 (2018).
Li, J. et al. Electrically addressing the spin of a magnetic porphyrin through covalently connected graphene electrodes. Nano Lett. 19, 3288–3294 (2019).
Mateo, L. M. et al. On‐surface synthesis and characterization of triply fused porphyrin–graphene nanoribbon hybrids. Angew. Chem. Int. Ed. 59, 1334–1339 (2020).
Yazyev, O. V. A guide to the design of electronic properties of graphene nanoribbons. Acc. Chem. Res. 46, 2319–2328 (2013).
Yazyev, O. V. Emergence of magnetism in graphene materials and nanostructures. Rep. Prog. Phys. 73, 056501 (2010).
Fairbrother, A. et al. High vacuum synthesis and ambient stability of bottom-up graphene nanoribbons. Nanoscale 9, 2785–2792 (2017).
Ma, C. et al. Oxidization stability of atomically precise graphene nanoribbons. Phys. Rev. Mater. 2, 014006 (2018).
Berdonces-Layunta, A. et al. Chemical stability of (3,1)-chiral graphene nanoribbons. ACS Nano 15, 5610–5617 (2021).
Yoon, K.-Y. & Dong, G. Liquid-phase bottom-up synthesis of graphene nanoribbons. Mater. Chem. Front. 4, 29–45 (2020).
Narita, A., Wang, X.-Y., Feng, X. & Müllen, K. New advances in nanographene chemistry. Chem. Soc. Rev. 44, 6616–6643 (2015).
Kan, E., Li, Z., Yang, J. & Hou, J. G. Half-metallicity in edge-modified zigzag graphene nanoribbons. J. Am. Chem. Soc. 130, 4224–4225 (2008).
Carbonell-Sanromà, E. et al. Doping of graphene nanoribbons via functional group edge modification. ACS Nano 11, 7355–7361 (2017).
Li, J. et al. Band depopulation of graphene nanoribbons induced by chemical gating with amino groups. ACS Nano 14, 1895–1901 (2020).
Anthony, J. E. The larger acenes: versatile organic semiconductors. Angew. Chem. Int. Ed. 47, 452–483 (2008).
Greene, T. W. & Wuts, P. G. M. Protective Groups in Organic Synthesis (Wiley, 1999).
Chia, C.-I. & Crespi, V. H. Stabilizing the zigzag edge: graphene nanoribbons with sterically constrained terminations. Phys. Rev. Lett. 109, 076802 (2012).
Li, Y., Zhou, Z., Cabrera, C. R. & Chen, Z. Preserving the edge magnetism of zigzag graphene nanoribbons by ethylene termination: insight by Clar’s rule. Sci. Rep. 3, 2030 (2013).
Sun, Z. et al. Dibenzoheptazethrene isomers with different biradical characters: an exercise of Clar’s aromatic sextet rule in singlet biradicaloids. J. Am. Chem. Soc. 135, 18229–18236 (2013).
Clair, S. & de Oteyza, D. G. Controlling a chemical coupling reaction on a surface: tools and strategies for on-surface synthesis. Chem. Rev. 119, 4717–4776 (2019).
Wang, T. & Zhu, J. Confined on-surface organic synthesis: strategies and mechanisms. Surf. Sci. Rep. 74, 97–140 (2019).
Held, P. A., Fuchs, H. & Studer, A. Covalent-bond formation via on-surface chemistry. Chem. Eur. J. 23, 5874–5892 (2017).
Song, S. et al. On-surface synthesis of graphene nanostructures with π-magnetism. Chem. Soc. Rev. 50, 3238–3262 (2021).
Liu, J. & Feng, X. Synthetic tailoring of graphene nanostructures with zigzag‐edged topologies: progress and perspectives. Angew. Chem. Int. Ed. 59, 23386–23401 (2020).
Li, J. et al. Single spin localization and manipulation in graphene open-shell nanostructures. Nat. Commun. 10, 200 (2019).
Mishra, S. et al. Topological frustration induces unconventional magnetism in a nanographene. Nat. Nanotechnol. 15, 22–28 (2020).
Zuzak, R. et al. On-surface synthesis of chlorinated narrow graphene nanoribbon organometallic hybrids. J. Phys. Chem. Lett. 11, 10290–10297 (2020).
Zuzak, R., Jančařík, A., Gourdon, A., Szymonski, M. & Godlewski, S. On-surface synthesis with atomic hydrogen. ACS Nano 14, 13316–13323 (2020).
de Oteyza, D. G. et al. Substrate-independent growth of atomically precise chiral graphene nanoribbons. ACS Nano 10, 9000–9008 (2016).
Merino-Díez, N. et al. Transferring axial molecular chirality through a sequence of on-surface reactions. Chem. Sci. 11, 5441–5446 (2020).
Merino-Díez, N. et al. Unraveling the electronic structure of narrow atomically-precise chiral graphene nanoribbons. J. Phys. Chem. Lett. 9, 25–30 (2018).
Li, J. et al. Topological phase transition in chiral graphene nanoribbons: from edge bands to end states. Nat. Commun. 12, 5538 (2021).
Konishi, A. & Kubo, T. Benzenoid quinodimethanes. Top. Curr. Chem. 375, 83 (2017).
Clar, E. The Aromatic Sextet (J. Wiley, 1972).
Mohammed, M. S. G. et al. Electronic decoupling of polyacenes from the underlying metal substrate by sp3 carbon atoms. Commun. Phys. 3, 159 (2020).
Merino-Díez, N. et al. Width-dependent band gap in armchair graphene nanoribbons reveals Fermi level pinning on Au(111). ACS Nano 11, 11661–11668 (2017).
Endo, O., Nakamura, M., Amemiya, K. & Ozaki, H. Graphene nanoribbons formed from n-alkane by thermal dehydrogenation on Au(111) surface. Surf. Sci. 635, 44–48 (2015).
Wang, T. et al. Magnetic interactions between radical pairs in chiral graphene nanoribbons. Nano Lett. 22, 164–171 (2022).
Itoh, T., Matsuno, M., Kamiya, E., Hirai, K. & Tomioka, H. Preparation of copper ion complexes of sterically congested diaryldiazomethanes having a pyridine ligand and characterization of their photoproducts. J. Am. Chem. Soc. 127, 7078–7093 (2005).
Di Giovannantonio, M. et al. On-surface growth dynamics of graphene nanoribbons: the role of halogen functionalization. ACS Nano 12, 74–81 (2018).
Berdonces-Layunta, A. et al. Order from a mess: the growth of 5-armchair graphene nanoribbons. ACS Nano 15, 16552–16561 (2021).
Blum, V. et al. Ab initio molecular simulations with numeric atom-centered orbitals. Comput. Phys. Commun. 180, 2175–2196 (2009).
Becke, A. D. Density‐functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Tkatchenko, A. & Scheffler, M. Accurate molecular van der Waals interactions from ground-state electron density and free-atom reference data. Phys. Rev. Lett. 102, 073005 (2009).
Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188–5192 (1976).
Lewis, J. P. et al. Advances and applications in the FIREBALL ab initio tight-binding molecular-dynamics formalism. Phys. Status Solidi B 248, 1989–2007 (2011).
Hapala, P. et al. Mechanism of high-resolution STM/AFM imaging with functionalized tips. Phys. Rev. B 90, 085421 (2014).
Krejčí, O., Hapala, P., Ondráček, M. & Jelínek, P. Principles and simulations of high-resolution STM imaging with a flexible tip apex. Phys. Rev. B 95, 045407 (2017).
Research was supported by MCIN/AEI/10.13039/501100011033 (grant nos PID2019-107338RB-C62 (D.P.), PID2019-107338RB-C63 (M.C. and D.G.d.O.) and FJC2019-041202-I (F.S.)); the European Union’s Horizon 2020 programme (grant nos 863098 (D.P.) and 635919 (D.G.d.O.), and Marie Skłodowska-Curie Actions Individual Fellowship no. 101022150 (T.W.)); the Gobierno Vasco (grant no. PIBA_2020_1_0036 (D.G.d.O.)); the Xunta de Galicia (Centro Singular de Investigación de Galicia, 2019–2022, grant no. ED431G2019/03 (D.P.)); the European Regional Development Fund; the Praemium Academie of the Academy of Science of the Czech Republic (GACR project no. 20-13692X (P.J.)); the Czech Nanolab Research Infrastructure supported by MEYS CR (project no. LM2018110 (P.J.)); and the Operational Programme for Research, Development and Education of the European Regional Development Fund (project no. CZ.02.1.01/0.0/0.0/16_019/0000754 (P.J.)). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
The authors have no competing interests.
Peer review information
Nature Chemistry thanks Junfa Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended Data Fig. 1 XPS analysis monitoring the hydrogenation/dehydrogenation process of pristine and ketone-functionalized ribbons.
(a) C1s XPS spectra (symbols) of p-chGNRs “as grown” (top), after hydrogenation (middle) and after subsequent annealing (bottom), along with the fit (solid curve) and its associated components (coloured peaks). The data reveal the successful hydrogenation and its reversibility. (b) C1s XPS spectra (symbols) of k-chGNRs “as grown” (top), after hydrogenation (middle) and after subsequent annealing (bottom), along with the fit (solid curve) and its associated components (coloured peaks). The data reveal the gradual deoxidation upon hydrogenation and the subsequent annealing. Dashed lines act as a guide to the eye to compare the maxima on each of the spectra. Details about the fitting procedure are given in the methods section.
Comparison between the structures of the two types of ketone-functionalized GNRs that were observed. (a) Typical STM image of a self-assembled island that contains both types of ketone-GNR. I = 50 pA, Vbias = −0.5 V. (b) BR-STM image of a metal-coordinated and (c) typical section of a ketone-NR island. Both constant height, CO tip, Vbias = 4 mV and 5 mV, respectively. Scale bars are both 500 pm. (d) and (e) Models of the metal-coordinated and typical islands, with suggested positions for gold adatoms in the metal-coordinated model.
(a) Overview STM image of a ketone-GNR sample that was exposed to air for 24 minutes, without any further treatment. I = 50 pA; Vbias = 1.5 V. (b) and (c): STM images of the same sample after annealing to 200 °C for 1 hour. (b) I = 20 pA; Vbias = −0.8 V. (c) I = 30 pA; Vbias = −0.8 V. Although most have desorbed, a notable number of contaminants are still present on the surface after the annealing treatment. Islands of alkyl chain contamination from the ambient conditions are indicated in (c) with a blue arrow.
Scanning probe microscopy images for Fig. 2.
Scanning probe microscopy images for Fig. 3.
Conductance spectra, scanning probe microscopy images, calculated band structure and calculated wavefunctions for Fig. 4.
Conductance spectra and calculated atomic positions for Fig. 5
Scanning probe microscopy images for Fig. 6.
Unprocessed XPS data for the pristine and ketone-functionalized ribbons as grown, after hydrogen exposure and after subsequent annealing.
Scanning probe microscopy images for Extended Data Fig. 2.
Scanning probe microscopy images for Extended Data Fig. 3.
About this article
Cite this article
Lawrence, J., Berdonces-Layunta, A., Edalatmanesh, S. et al. Circumventing the stability problems of graphene nanoribbon zigzag edges. Nat. Chem. (2022). https://doi.org/10.1038/s41557-022-01042-8