Huang, Y. L., Yang, K., Yang, J., Duan, S., Wang, Y., Sun, M., Zhang, Y., Yang, M., & Wee, A. T. S. (2025). Redirecting On‐surface Cycloaddition Reactions in a Self‐assembled Ordered Molecular Array on Graphite. Angewandte Chemie. Portico. https://doi.org/10.1002/ange.202425185
Abstract:
The synthesis of atomically precise carbon nanostructures in ultra‐high vacuum has seen extensive progress on metal surfaces. However, this remains challenging on chemically inert surfaces. It is because the thermally activated C−C coupling encounters a severe “desorption problem” on weakly interacting substrates. In this study, we report an extraordinary [2+2]+[2+2] cycloaddition triggered by mild annealing (~210°C) in a highly ordered π‐conjugated molecular array on graphite using scanning tunneling microscopy. In contrast to irregular dendritic fragments typically obtained on metal substrates, large supramolecular islands are observed here with cycloaddition products and other polymers over 30 %, which are embedded as defective individuals or chains (grain boundaries). First‐principles calculations reveal that the energy barriers of the multiple dehydrohalogenation and cycloaddition reactions are reduced by catalytic Fe atoms but remain energetically unfavorable. A distinct driving mechanism is proposed for redirecting the reactions on graphite surface, where additional intermolecular coupling, steric hindrance, and interfacial interactions play significant roles. This study introduces a new paradigm for understanding on‐surface synthesis on non‐metal substrates.
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Funding Info:
This research / project is supported by the Agency for Science, Technology and Research, Italy-Singapore Science and Technology Cooperation - EURIPIDES
Grant Reference no. : R23101R040
This research / project is supported by the Agency for Science, Technology and Research, Science and Engineering Research Council - Central Research Fund
Grant Reference no. : NA
This research / project is supported by the National Research Foundation, Singapore - Competitive Research Programme
Grant Reference no. : CRP26-2021RS-0001
Description:
This is the peer reviewed version of the following article: Huang, Y. L., Yang, K., Yang, J., Duan, S., Wang, Y., Sun, M., Zhang, Y., Yang, M., & Wee, A. T. S. (2025). Redirecting On‐surface Cycloaddition Reactions in a Self‐assembled Ordered Molecular Array on Graphite. Angewandte Chemie. Portico, which has been published in final form at https://doi.org/10.1002/ange.202425185. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.