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Intrinsic Properties of Single Graphene Nanoribbons in Solution: Synthetic and Spectroscopic Studies Yinjuan Huang, Fugui Xu, Lucia Ganzer, Franco V. A. Camargo, Tetsuhiko NAGAHARA, Joan Teyssandier, Hans van Gorp, Kristoffer Basse, Lasse Arnt Straasø, Vaiva Nagyte, Cinzia Casiraghi, Michael Ryan Hansen, Steven De Feyter, Deyue Yan, Klaus Müllen, Xinliang Feng, Giulio Cerullo, and Yiyong Mai J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 07 Aug 2018 Downloaded from http://pubs.acs.org on August 7, 2018
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Journal of the American Chemical Society
Yinjuan Huang1#, Fugui Xu1#, Lucia Ganzer2, Franco V. A. Camargo2, Tetsuhiko Nagahara2,3, Joan Teyssandier4, Hans Van Gorp4, Kristoffer Basse5, Lasse Arnt Straasø5, Vaiva Nagyte6, Cinzia Casiraghi6, Michael Ryan Hansen7, Steven De Feyter4, Deyue Yan1, Klaus Müllen8, Xinliang Feng9, Giulio Cerullo2*, and Yiyong Mai1* School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan RD, Shanghai 200240, China; 2 IFN-CNR, Dipartimento di Fisica, Piazza L. da Vinci 32, 20133 Milano, Italy; 3 Department of Chemistry and Materials Technology, Kyoto Institute of Technology, 606-8585 Kyoto, Japan; 4 Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven Celestijnenlaan, 200 F, B-3001 Leuven, Belgium; 5 Interdisciplinary Nanoscience Center, Aarhus University, Gustav Wieds Vej 14, DK-8000 Aarhus C, Denmark; 6 School of Chemistry, University of Manchester, Oxford Road, Manchester M139PL, United Kingdom; 7 Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstr. 28/30, D-48149 Münster, Germany; 8 Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany; 9 Department of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062 Dresden, Germany. Supporting Information 1
ABSTRACT: We report a novel type of structurally defined graphene nanoribbons (GNRs) with uniform width of 1.7 nm and average length up to 58 nm. These GNRs are decorated with pending Diels-Alder cycloadducts of anthracenyl units and N-n-hexadecyl maleimide. The resultant bulky side groups on GNRs afford excellent dispersibility with concentrations of up to 5 mg mL-1 in many organic solvents such as tetrahydrofuran (THF), two orders of magnitude higher than the previously reported GNRs. Multiple spectroscopic studies confirm that dilute dispersions in THF (< 0.1 mg mL-1) consist mainly of non-aggregated ribbons, exhibiting near-infrared emission with high quantum yield (9.1%) and long lifetime (8.7 ns). This unprecedented dispersibility allows resolving in real-time ultrafast excited-state dynamics of the GNRs, which displays features of small isolated molecules in solution. This study achieves a breakthrough in the dispersion of GNRs, which opens the door for unveiling obstructed GNR-based physical properties and potential applications. Structurally defined graphene nanoribbons (GNRs) have attracted increasing interest due to their tunable optical, electronic and magnetic properties by tailoring their width and/or edge structures.1-18 Two “bottom-up” strategies, including surface-assisted1-7 and solution-based organic synthesis,9-17 were developed for GNRs. In contrast to the surface-mediated method, the solution synthesis shows significant advantages in large-scale preparation of liquid-phase-dispersible GNRs.917 However, controlling the physical properties of GNRs, such as optical bandgap and carrier mobility, will be only possible if individual GNRs can be achieved. Otherwise aggregation effects, which could so far never be excluded, would obscure their intrinsic physical properties.10-17
~1.7 nm
~1 nm
5 ~ 60 nm GNR-AHM-1, 2 & 3
PPP-AHM-1, 2 & 3 O R = R
N
=
O
Scheme 1. Synthesis of GNR-AHM. The bulky AHM group size is determined by Chem3D. GNR-AHM-1, 2 & 3 possess average lengths of ca. 6, 11 and 58 nm, respectively.
Here, we demonstrate the solution synthesis of a new type of GNRs (hereafter GNR-AHM) with a uniform width of 1.7 nm and average lengths up to 58 nm, which are decorated with pending Diels-Alder cycloadducts of anthracenyl units and Nn-hexadecyl maleimide (AHM) (Scheme 1). The AHM side groups have radius of 0.5 nm, which is larger than the interlayer spacing of graphite (0.34 nm),19-21 effectively hindering the - stacking (Scheme S1). GNR-AHMs show unprecedented dispersibility in many organic solvents (e.g. tetrahydrofuran, THF) with concentrations of up to 5 mg mL-1 (for GNR backbone excluding AHM unless otherwise mentioned). Atomic force microscopy (AFM) analysis of GNR-AHM deposited on graphite substrate shows a periodic selfassembled monolayer structure with a lateral side-by-side alignment of single ribbons. Dynamic light scattering (DLS), steady state and transient absorption (TA) spectroscopies
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Journal of the American Chemical Society suggest a single-ribbon feature of the GNRs in dilute dispersions (e.g.
