Remote-Triggered Domino-like Cyclodehydrogenation in Second-Layer Topological Graphene Nanoribbons

Chuanxu Ma; Jufeng Wang; Huanhuan Ma; Ruoting Yin; Xin-Jing Zhao; Hongjian Du; Xinyong Meng; Yifan Ke; Wei Hu; Bin Li; Shijing Tan; Yuan-Zhi Tan; Jinlong Yang; Bing Wang

doi:10.1021/jacs.3c00563

Remote-Triggered Domino-like Cyclodehydrogenation in Second-Layer Topological Graphene Nanoribbons

J Am Chem Soc. 2023 May 10;145(18):10126-10135. doi: 10.1021/jacs.3c00563. Epub 2023 Apr 25.

Authors

Chuanxu Ma^{1

2}, Jufeng Wang¹, Huanhuan Ma¹, Ruoting Yin¹, Xin-Jing Zhao³, Hongjian Du^{1

2}, Xinyong Meng¹, Yifan Ke¹, Wei Hu^{1

2}, Bin Li^{1

2}, Shijing Tan^{1

2}, Yuan-Zhi Tan³, Jinlong Yang^{1

2}, Bing Wang^{1

2

4}

Affiliations

¹ Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
² Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China.
³ Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China.
⁴ New Cornerstone Science Laboratory, Shenzhen 518054, China.

PMID: 37097709
DOI: 10.1021/jacs.3c00563

Abstract

Cyclodehydrogenation reactions in the on-surface synthesis of graphene nanoribbons (GNRs) usually involve a series of C_sp2-C_sp2 and/or C_sp2-C_sp3 couplings and just happen on uncovered metal or metal oxide surfaces. It is still a big challenge to extend the growth of second-layer GNRs in the absence of necessary catalytic sites. Here, we demonstrate the direct growth of topologically nontrivial GNRs via multistep C_sp2-C_sp2 and C_sp2-C_sp3 couplings in the second layer by annealing designed bowtie-shaped precursor molecules over one monolayer on the Au(111) surface. After annealing at 700 K, most of the polymerized chains that appear in the second layer covalently link to the first-layer GNRs that have partially undergone graphitization. Following annealing at 780 K, the second-layer GNRs are formed and linked to the first-layer GNRs. Benefiting from the minimized local steric hindrance of the precursors, we suggest that the second-layer GNRs undergo domino-like cyclodehydrogenation reactions that are remotely triggered at the link. We confirm the quasi-freestanding behaviors in the second-layer GNRs by measuring the quasiparticle energy gap of topological bands and the tunable Kondo resonance from topological end spins using scanning tunneling microscopy/spectroscopy combined with first-principles calculations. Our findings pave the avenue to diverse multilayer graphene nanostructures with designer quantum spins and topological states for quantum information science.