Chirality variation from self-assembly on Ullmann coupling for the DBCh adsorbate on Au(111) and Ag(111)

Hongbing Wang; Jinping Hu; Zhaofeng Liang; Huan Zhang; Chaoqin Huang; Lei Xie; Zheng Jiang; Han Huang; Fei Song

doi:10.1039/d2na00789d

Chirality variation from self-assembly on Ullmann coupling for the DBCh adsorbate on Au(111) and Ag(111)

Nanoscale Adv. 2023 Jan 26;5(5):1368-1377. doi: 10.1039/d2na00789d. eCollection 2023 Feb 28.

Authors

Hongbing Wang^{1

2}, Jinping Hu^{1

2}, Zhaofeng Liang³, Huan Zhang^{1

2}, Chaoqin Huang^{1

2}, Lei Xie³, Zheng Jiang^{1

2

3}, Han Huang⁴, Fei Song^{1

2

3}

Affiliations

¹ Shanghai Institute of Applied Physics Zhangheng Road 239 Shanghai 201000 China songfei@sinap.ac.cn.
² University of Chinese Academy of Sciences Beijing 100000 China.
³ Shanghai Advanced Research Institute Zhangheng Road 239 Shanghai 201004 China liangzf@sari.ac.cn.
⁴ School of Physics and Electronics, Central South University Changsha 410073 China.

Abstract

On-surface Ullmann coupling has been considered an appealing approach for the precise fabrication of carbon-based covalent nanostructures under solution-free conditions. However, chirality has seldom been discussed in Ullmann reactions. In this report, self-assembled two-dimensional chiral networks are initially constructed in a large area on Au(111) and Ag(111) after adsorption of the prochiral precursor, 6,12-dibromochrysene (DBCh). Self-assembled phases are then transformed into organometallic (OM) oligomers after debromination, preserving the chirality; in particular, the formation of scarcely reported OM species on Au(111) is discovered herein. With the aryl-aryl bonding induced after intensive annealing, covalent chains are fabricated via the cyclodehydrogenation between chrysene blocks, resulting in the formation of 8-armchair graphene nanoribbons with staggered valleys on both sides. Before chiral polymer chains are constructed by chrysene blocks, the high structural flexibility of OM intermediates on Ag(111) is also revealed during reactions, which is derived from the twofold coordination of Ag atoms and conformationally flexible metal-carbon bonding. Our report not only provides solid evidence of atomically precise fabrication of covalent nanostructures with a feasible bottom-up approach but also sheds insights into the comprehensive investigation of chirality variation from monomers to artificial architectures via surface coupling reactions.