Probing the Intermediates of Catalyzed Dehydration Reactions of Primary Amide to Nitrile in Plasmonic Junctions
Probing the Intermediates of Catalyzed Dehydration Reactions of Primary Amide to Nitrile in Plasmonic Junctions
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DOI：
10.1021/acscatal.2c01793
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发表时间：
2022-06
期刊：
影响因子：
12.9
通讯作者：
Jianghao Zhou;Jing Guo;A. Mebel;Govinda Ghimire;Feng Liang;Shuai Chang;Jin He
中科院分区：
文献类型：
--
作者：
Jianghao Zhou;Jing Guo;A. Mebel;Govinda Ghimire;Feng Liang;Shuai Chang;Jin He
可见光可以有效地驱动等离子体分子结中的化学反应，这是由于等离子体金属纳米结构表面处的吸附原子的高反应性以及局部表面等离子体共振（LSPR）诱导的高能电荷载流子（电子和空穴）和热。在这里，我们研究了伯酰胺的脱水反应，这是重要的生成有价值的腈分子，在可见光照射的自组装金纳米粒子-芳香伯酰胺-金纳米电极结在水溶液中在环境条件下。目前对伯酰胺基团脱水反应的研究仅停留在宏观水平，限制了反应动力学和中间体的机理研究。使用时间分辨表面增强拉曼光谱（Sers）与几十毫秒的时间分辨率，我们成功地遵循了演变的Sers光谱沿着各种瞬态光谱变化的腈振动峰的上升。结合密度泛函理论和picocavity模型，我们发现，最显着的瞬态光谱变化是从金表面吸附原子耦合的反应中间体。吸附原子产生的picocavities与一个强大的原子大小的本地字段，这强烈增强的Sers信号的中间下降到亚单分子的分辨率。活性吸附原子在中间体的产生、相互作用和稳定过程中起着关键作用。我们已经确定了复杂的反应途径，涉及多个质子转移步骤和中间体的签名碳氮双键和三键。
Visible light can effectively drive chemical reactions in plasmonic molecular junctions owing to the high reactivity of adatoms at the surface of plasmonic metal nanostructures and the localized surface plasmon resonance (LSPR)-induced energetic charge carriers (electrons and holes) and heat. Here, we investigated the dehydration reaction of primary amides, which is important to generate valuable nitrile molecules, in the visible-light-irradiated self-assembled gold nanoparticle–aromatic primary amide–gold nanoelectrode junctions in aqueous solution under ambient conditions. At present, the research on the dehydration reaction of the primary amide group is only at the macroscopic level, limiting the mechanistic study of reaction dynamics and intermediates. Using time-resolved surface enhanced Raman spectroscopy (SERS) with tens of millisecond time resolution, we successfully followed the evolution of the SERS spectra along with various transient spectral changes during the rise of the nitrile vibration peak. Combined with density functional theory and a picocavity model, we revealed that most pronounced transient spectral changes were from the gold surface adatom-coupled reaction intermediates. The adatoms produced picocavities with a strong atomic size local field, which strongly enhanced the SERS signals of the intermediates down to sub-single-molecule resolution. The active adatoms played critical roles in producing, interacting, and stabilizing the intermediates. We have determined the complex reaction pathway involving multiple proton transfer steps and intermediates with signature carbon–nitrogen double and triple bonds.