On-Surface Synthesis of Functionalized Honeycombene Macrocycles and Related Two-Dimensional Polymer Structures
Physical Chemistry of Solids and Surfaces, Material Characterisation
Final Report Abstract
We successfully explored the on‐surface synthesis (OSS) of honeycombenes and related nanographenes, nanoribbons, and 2D polymers. The results were published in high‐ranking journals including Science (1), J. Am. Chem. Soc. (4), Nature Comm. (1), ACS Nano (5) and Chem. Comm. (1). Mechanistic studies resulted in a thorough understanding of on‐surface reactivity as a solid basis for a high degree of selectivity control. Deviations from the originally planned work were necessary to stay competitive in a highly dynamic field of research. Reaction control in on‐surface synthesis: We developed novel concepts for selective reaction control in OSS. To obtain high yields of macrocycles in OSS, various approaches were developed including thermodynamic and kinetic control, steric control through precursor design, control by surface interactions and surface structure, as well as 0D and 1D surface templates. These methods are partly applied in combination. Extensive mechanistic studies of OSS reaction were performed to establish and optimize the principles of reaction control and to maximize yields and selectivities. Moreover, we expanded the tool box of reaction types in OSS, for example with the interpolymer dehydrofluorination (HF‐zipping) reaction. Macrocycles: We synthesized various π‐conjugated oligophenylene macrocycles such as the hexagonal honeycombenes and related molecules with square, pentagonal and heptagonal symmetry. Detailed mechanistic studies were performed to understand the competition of ring formation versus chain growth in on‐surface polymerization. Novel approaches for controlling the ring/chain competition were introduced, such as the on‐surface high‐dilution principle, on‐surface templates, and other kinetic / thermodynamic principles. Another ground‐breaking achievement was the first OSS of a cycloarene. This hexagonal nanographene macrocycle (C108H36) and a related compound were synthesized by cyclotrimerization using Ullmann coupling, followed by cyclodehydrogenation. The reaction was carefully controlled by precursor design and adsorbate‐substrate interactions. We also achieved the first OSS of kekulene as a prototypical cycloarene. The reaction proceeds with very high yield and selectivity, resulting in ordered monolayers of kekulene. The sample quality was even sufficient for orbital tomography experiments, which confirmed the Clar model of aromaticity for kekulene. Using OSS, we also achieved the first synthesis of a superphthalocyanine (superPC) derivative without uranium. In solution, the ‐extended superPCs form only with uranium and decompose on attempts to exchange the metal center. Using the 2D confinement and template effects, made the first Gd‐superPC derivative. In addition, various other organometallic macrocycles were synthesized and used e.g. for studying the ring/chain competition in on‐surface reactions. Nanoribbons and 2D carbon materials: We synthesized the first planar all‐sp2 carbon allotrope besides graphene. This new material, biphenylene network, contains 4‐, 6‐, and 8‐membered rings and was made on a gold surface using a novel reaction type (inter‐polymer dehydrofluorination). Before, we succeeded in making the first azulene‐based carbon nanoribbons with 4‐, 5‐, 6‐, and 7‐membered rings (phagraphene, TPH‐graphene). Due to their non‐benzenoid and/or non‐alternant topology, these carbon materials have unique properties that are very different from those of graphene, such as metallicity at very small dimensions. Some of our results received considerable attention in the media, social networks, and the scientific literature.
Publications
- Confined Synthesis of Organometallic Chains and Macrocycles by Cu–O Surface Templating. ACS Nano 10 (2016) 3747‐3754
Q. Fan, J. Dai, T. Wang, J. Kuttner, G. Hilt, J.M. Gottfried, J.F. Zhu
(See online at https://doi.org/10.1021/acsnano.6b00366) - The role of the substrate structure in the on‐surface synthesis of organometallic and covalent oligophenylene chains. Phys. Chem. Chem. Phys. 18 (2016) 20627‐20634
J. Dai, Q. Fan, T. Wang, J. Kuttner, G. Hilt, J.M. Gottfried, J.F. Zhu
(See online at https://doi.org/10.1039/c6cp03551e) - On‐Surface Pseudo‐High Dilution Synthesis of Macrocycles: Principle and Mechanism. ACS Nano 11 (2017) 5070‐5079
Q.T. Fan, T. Wang, J. Dai, J. Kuttner, G. Hilt, J. M. Gottfried, J. F. Zhu
(See online at https://doi.org/10.1021/acsnano.7b01870) - On‐Surface Synthesis and Characterization of Honeycombene Oligophenylene Macrocycles. ACS Nano 11 (2017) 134‐143
M. Chen, J. Shang, Y. Wang, K. Wu, J. Kuttner, G. Hilt, W. Hieringer, J.M. Gottfried
(See online at https://doi.org/10.1021/acsnano.6b05709) - Precise Mono‐Selective Aromatic C‐H Bond Activation by Chemisorption of Meta‐Aryne on a Metal Surface. J. Am. Chem. Soc. 140 (2018) 7526‐7532
Q.T. Fan, S. Werner, J. Tschakert, D. Ebeling, A. Schirmeisen, G. Hilt, W. Hieringer, J.M. Gottfried
(See online at https://doi.org/10.1021/jacs.8b01658) - Surface Adatom Mediated Structural Transformation in Bromoarene Monolayers: Precursor Phases in Surface Ullmann Reaction. ACS Nano 12 (2018) 2267‐2274
Q.T. Fan, L. Liu, J. Dai, T. Wang, H. Ju, J. Zhao, J. Kuttner, G. Hilt, J. M. Gottfried, J.F. Zhu
(See online at https://doi.org/10.1021/acsnano.7b06787) - Nanoribbons with Non‐Alternant Topology from Fusion of Polyazulene: Carbon Allotropes Beyond Graphene. J. Am. Chem. Soc. 141 (2019) 17713‐17720
Q.T. Fan, D. Martin‐Jimenez, D. Ebeling, C.K. Krug, L. Brechmann, C. Kohlmeyer, G. Hilt, W. Hieringer, A. Schirmeisen, J.M. Gottfried
(See online at https://doi.org/10.1021/jacs.9b08060) - Template‐Controlled On‐Surface Synthesis of a Lanthanide Supernaphthalocyanine and its Open‐Chain Polycyanine Counterpart. Nature Comm. 10 (2019) 5049
Q.T. Fan, J.‐N. Luy, M. Liebold, K. Greulich, M. Zugermeier, J. Sundermeyer, R. Tonner, J.M. Gottfried
(See online at https://doi.org/10.1038/s41467-019-13030-7) - On‐Surface Synthesis and Characterization of a Cycloarene: C108 Graphene Ring. J. Am. Chem. Soc. 142 (2020) 894‐899
Q.T. Fan, D. Martin‐Jimnez, S. Werner, D. Ebeling, T. Koehler, T. Vollgraff, J. Sundermeyer, W. Hieringer, A. Schirmeisen, J.M. Gottfried
(See online at https://doi.org/10.1021/jacs.9b10151) - Biphenylene Network: A Nonbenzenoid Carbon Allotrope. Science 372 (2021) 852‐856
Q.T. Fan, L.H. Yan, M.W. Tripp, O. Krejči, S. Dimosthenous, S.R. Kachel, M.Y. Chen, A.S. Foster, U. Koert, P. Liljeroth, J.M. Gottfried
(See online at https://doi.org/10.1126/science.abg4509)
