Direct single-molecule dynamic detection of chemical reactions.
Direct single-molecule dynamic detection of chemical reactions.
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DOI：
10.1126/sciadv.aar2177
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发表时间：
2018-03
期刊：
影响因子：
13.6
通讯作者：
Guo X
中科院分区：
文献类型：
--
作者：
Guan J;Jia C;Li Y;Liu Z;Wang J;Yang Z;Gu C;Su D;Houk KN;Zhang D;Guo X
已经在石墨烯-分子单分子连接中研究了亲核加成反应的动态过程。单分子检测可以揭示化学反应和生物过程中各个中间体/过渡态的时间轨迹和反应途径，这对于阐明其内在机制具有重要意义。我们提出了一种可靠的、无标记的单分子方法，使我们能够通过使用稳定的石墨烯-分子单分子连接直接探索单事件水平上基本化学反应的动态过程。这些连接是通过将具有 9-芴酮中心的单个分子共价连接到纳米间隙石墨烯电极而构建的。实时单分子电学测量首次明确地显示了可重复的大幅两级波动，这些波动高度依赖于羟胺与羰基的亲核加成反应中的溶剂环境。理论模拟和系综实验都证明，这一观察源于反应物在几微秒的时间尺度内与新的中间态之间的可逆转变。这些研究开辟了一条新途径，能够立即应用于探测高时间分辨率的快速单分子物理学或生物物理学，为反应化学以外的广泛领域做出了重要贡献。
The dynamic process of a nucleophilic addition reaction has been investigated in graphene-molecule single-molecule junctions. Single-molecule detection can reveal time trajectories and reaction pathways of individual intermediates/transition states in chemical reactions and biological processes, which is of fundamental importance to elucidate their intrinsic mechanisms. We present a reliable, label-free single-molecule approach that allows us to directly explore the dynamic process of basic chemical reactions at the single-event level by using stable graphene-molecule single-molecule junctions. These junctions are constructed by covalently connecting a single molecule with a 9-fluorenone center to nanogapped graphene electrodes. For the first time, real-time single-molecule electrical measurements unambiguously show reproducible large-amplitude two-level fluctuations that are highly dependent on solvent environments in a nucleophilic addition reaction of hydroxylamine to a carbonyl group. Both theoretical simulations and ensemble experiments prove that this observation originates from the reversible transition between the reactant and a new intermediate state within a time scale of a few microseconds. These investigations open up a new route that is able to be immediately applied to probe fast single-molecule physics or biophysics with high time resolution, making an important contribution to broad fields beyond reaction chemistry.
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