Identifying Enclosed Chemical Reaction and Dynamics at the Molecular Level Using Shell-Isolated Miniaturized Plasmonic Liquid Marble

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• 作者：Xuemei Han ; Hiang Kwee Lee ; Yih Hong Lee ; Wei Hao ; Yejing Liu ; In Yee Phang ; Shuzhou Li ; Xing Yi Ling
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：April 21, 2016
• 年：2016
• 卷：7
• 期：8
• 页码：1501-1506
• 全文大小：461K
• 年卷期：0
• ISSN：1948-7185

文摘

Current microscale tracking of chemical kinetics is limited to destructive ex situ methods. Here we utilize Ag nanocube-based plasmonic liquid marble (PLM) microreactor for in situ molecular-level identification of reaction dynamics. We exploit the ultrasensitive surface-enhanced Raman scattering (SERS) capability imparted by the plasmonic shell to unravel the mechanism and kinetics of aryl-diazonium surface grafting reaction in situ, using just a 2-μL reaction droplet. This reaction is a robust approach to generate covalently functionalized metallic surfaces, yet its kinetics remain unknown to date. Experiments and simulations jointly uncover a two-step sequential grafting process. An initial Langmuir chemisorption of sulfonicbenzene diazonium (dSB) salt onto Ag surfaces forms an intermediate sulfonicbenzene monolayer (Ag–SB), followed by subsequent autocatalytic multilayer growth of Ag–SB₃. Kinetic rate constants reveal 19-fold faster chemisorption than multilayer growth. Our ability to precisely decipher molecular-level reaction dynamics creates opportunities to develop more efficient processes in synthetic chemistry and nanotechnology.