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Dissymmetric On-Surface Dehalogenation Reaction Steered by Preformed Self-Assembled Structure
Hui Lu1,2, Wenlong E1,2, Liangliang Cai3
1State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China.
The Journal of Physical Chemistry Letters
|February 20, 2020
Summary
Researchers controlled Ullmann coupling reactions of 4,4″-dibromo-p-terphenyl (DBTP) on silver surfaces. Pre-assembly directed the reaction pathway, enabling selective dissymmetric dehalogenation for on-surface synthesis.
Area of Science:
- Surface Chemistry
- Organic Synthesis
- Materials Science
Background:
- Ullmann coupling is a key reaction for forming carbon-carbon bonds.
- Controlling reaction pathways on surfaces is crucial for on-surface synthesis.
- 4,4″-dibromo-p-terphenyl (DBTP) is a suitable precursor for surface-mediated coupling reactions.
Purpose of the Study:
- To investigate the Ullmann coupling of DBTP on a Ag(111) surface.
- To explore the influence of molecular self-assembly on reaction pathways.
- To achieve controlled dissymmetric dehalogenation for on-surface synthesis.
Main Methods:
- Scanning tunneling microscopy (STM) for real-space observation.
- Thermal catalysis on a Ag(111) single crystal surface.
- Controlled pre-self-assembly of DBTP molecules.
Main Results:
- Ullmann coupling of DBTP on Ag(111) was successfully studied.
- Molecular self-assembly dictates the Ullmann coupling reaction pathways.
- Dissymmetric dehalogenation was achieved through controlled self-assembly into a rectangular network, leading to a rhombic organometallic intermediate.
- Ladder-like self-assembled structures favored symmetric dehalogenation.
Conclusions:
- The pre-self-assembly of DBTP molecules on Ag(111) enables control over Ullmann coupling reaction pathways.
- Dissymmetric dehalogenation can be selectively induced by controlling the initial molecular arrangement.
- These findings advance the understanding of on-surface synthesis and offer new strategies for creating complex molecular architectures.
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