Symmetrical dehalogenation of 2, 7-dibromopyrene on Cu(111) with tunable intermediates and reaction paths
Symmetrical dehalogenation of 2, 7-dibromopyrene on Cu(111) with tunable intermediates and reaction paths
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2, 7-二溴芘在 Cu(111) 上的对称脱卤反应，中间体和反应路径可调
DOI：
10.1016/j.apsusc.2021.150663
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发表时间：
2021
影响因子：
6.7
通讯作者：
Fei Song
中科院分区：
文献类型：
--
作者：
Jinping Hu;Zhaofeng Liang;Hongbing Wang;Huan Zhang;Chaoqin Huang;Lei Xie;Zheshen Li;Zheng Jiang;Han Huang;Fei Song
表面Ullmann耦合由于其在高可控性的共轭纳米结构的定制化制备方面的独特性，近年来引起了人们的广泛关注。然而，对反应机制的深入了解尚未完全建立。本文通过扫描隧道显微镜、X射线光电子能谱和密度泛函理论的结合，详细研究了2，7-二溴芘（Br 2 Py）在Cu（111）上的对称脱卤反应。首先，Br 2 Py在预冷却的Cu（111）上的沉积导致完整前体的自组装，而由于Cu在室温下的相对高的反应性，在对称脱卤之后在保持在室温（RT）下的Cu（111）上诱导有机金属（OM）链的形成。已经有趣地发现对称脱溴残留物可以结合到来自底物的铜原子上导致形成紧密堆积的物质，或者当Cu（111）在沉积过程中保持在升高的温度下时形成Kagome样图案的表面吸附原子。尽管如此，经过逐步退火后，最终由不同的OM中间体构建了共价有机链，并清楚地识别了结构转变的指纹。基于这些发现，我们的报告提供了全面了解表面乌尔曼耦合机制的吸引力的见解。
On-surface Ullmann coupling has attracted intensive attentions recently owing to its uniqueness at the tailor-made fabrication of conjugated nanostructures with high controllability. However, in-depth understanding of reaction mechanisms has not been fully established yet. Herein, symmetrical dehalogenation of 2, 7-dibromopyrene (Br2Py) on Cu(1 1 1) has been investigated in-detail via a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory. First, deposition of Br2Py onto the precooled Cu(1 1 1) results in the self-assembly of intact precursors, while the formation of organometallic (OM) chains is induced on Cu(1 1 1) kept at room temperature (RT) after symmetrical dehalogenation due to the relatively high reactivity of Cu at RT. Further, it has been intriguingly discovered that symmetrically debrominated residues can be bound either to copper atoms from substrate leading the formation of close packed species, or to surface adatoms forming the Kagome-like pattern when Cu(1 1 1) is held at elevated temperatures during deposition. Nevertheless, covalent organic chains are constructed ultimately from different OM intermediates after stepwise annealing with the fingerprint of structural transition clearly identified. Based on these findings, our report provides appealing insights for the comprehensive understanding of surface Ullmann coupling mechanisms.