Nanophotonic Strategies for Making Molecular Movies of Catalysis

在这项研究中，在化学系化学结构动力学和机理(CSDM-A)、化学催化(CAT)和化学测量与成像(CMI)计划的支持下，威斯康星大学麦迪逊分校的兰德尔·戈德史密斯教授和他的研究团队试图更好地了解化学催化剂如何发挥其重要作用。催化剂允许进行困难的化学反应，但它们如何做到这一点可能涉及许多难以遵循的单独步骤。戈德史密斯教授正在使用一种新的方法，它结合了光学显微镜、某些分子的发光行为(在这种情况下，一种被称为“荧光”的特性)和纳米技术，以允许观察单个催化剂分子。戈德史密斯团队实质上是在开发单个可操作催化剂的“分子电影”。这一研究项目不仅为催化化学反应提供了新的见解，还开发了一种可能在许多其他化学、生物和材料科学研究中有用的实验室技术。参与这项研究的学生正在获得广泛的技能，从化学合成、光学显微镜到纳米制造。特别是，该项目重点研究在制药行业中广泛使用的钯交叉偶联反应。一个关键的因素是使用纳米光子器件来雕刻光，使其大大小于衍射极限，从而能够在化学相关浓度下观察单分子动力学。单个催化剂分子被固定在这些装置中，并通过单分子荧光显微镜进行研究。一个主要的读数是单个催化剂分子的时变速率常数和瞬时中间体的时间刻度。这项工作的更广泛影响包括可以为下一代催化剂分子的设计提供信息的机械工具的社会效益，对学生进行跨学科化学科学的培训，以及开发可在学校部署的单分子可视化演示，以扩大STEM少数民族的参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In this study, supported by the Chemical Structure Dynamics and Mechanism (CSDM-A), Chemical Catalysis (CAT) and Chemical Measurement and Imaging (CMI) Program of the Chemistry Division, Professor Randall Goldsmith and his research team at the University of Wisconsin Madison seek to better understand how chemical catalysts perform their important functions. Catalysts allow difficult chemical reactions to be proceed, but how they do this may involve many individual steps that are difficult to follow. Professor Goldsmith is using a new approach that combines optical microscopy, the light-emitting behaviors of certain molecules (in this case, a property called "fluorescence"), and nanotechnology to to allow observation of single catalyst molecules. The Goldsmith team is essentially developing "molecular movies" of an individual operational catalysts. This research project is not only providing new insights into catalytic chemical reactions, but also developing a laboratory technique that may be useful in many other chemistry, biology and materials science investigations. The students involved in this research are gaining a wide range of skills, from chemical synthesis, optical microscopy, and nano-fabrication. In particular, the project focuses on palladium cross-coupling reactions, which are widely employed in the pharmaceutical industry. A critical element is the use of nanophotonic devices that sculpt light to make it substantially smaller than the diffraction-limit, allowing observation of single-molecule dynamics at chemically relevant concentrations. Individual catalyst molecules are immobilized in these devices and studied via single-molecule fluorescence microscopy. A major readout is the time-varying rate constant of a single catalyst molecule and the timescale of transient intermediates. The broader impacts of this work include the societal benefits of a mechanistic tool that can inform the design of the next generation of catalyst molecules, the training of students in interdisciplinary chemical sciences, and the development of single-molecule visualization demos that can be deployed in schools to broaden participation of STEM minorities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.