Fluorescence-Encoded Infrared Spectroscopy for Single-Molecule Chemical Dynamics

在化学系化学结构、动力学和机理(CSDM-A)计划的支持下，芝加哥大学的Andrei Tokmakoff教授和他的研究小组正在开发新的技术来研究溶液中单个分子的随时间变化的行为。这些方法揭示了化学反应过程中分子的运动和相互作用，这是以前无法理解的。单分子(SM)方法对描述发生在表面和生物过程中的分子过程产生了巨大的影响，但它们在解决溶液相化学问题中的应用仍然是一个持久的挑战。该项目试图通过使用一种新的高灵敏度检测策略--荧光编码红外光谱(FEIR)来克服早期的限制，目标是使用振动光谱来跟踪溶液中单分子的化学键和分子接触是如何随时间演变的。从事这个项目的学生接受跨学科的培训，提供包括仪器开发、光学和光谱学以及化学动力学在内的一系列主题的经验。托克马科夫小组的这项培训为学生在学术和国家实验室或高科技公司的科学研究中担任领导角色做好准备。这项赠款支持的研究建立在托克马科夫教授和他的团队最近的工作基础上，他们使用光子相关光谱(CS)证明了FEIR方法的单分子敏感性。该团队现在正在扩展FEIR技术的能力，使用新型的生色团来瞄准各种化学应用。例如，研究小组正在为FEIR-CS开发红外振动对比机制，该机制使用振动频移作为化学动力学的记录器，用于特定位置的双分子结合、质子化和去质子化反应以及离子通过电解液的传输。此外，该团队正在努力扩展FEIR测量，以测量描述单个扩散和反应分子的键特定历史的单分子光子流的动态信息含量。这些研究工作的总目标是建立一个广泛适用的工具来研究液体、溶液和其他软材料中的化学动力学和分子传输过程。该项目更广泛的影响还包括开发和传播开放获取的教育资源。这一奖项反映了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。

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, Professor Andrei Tokmakoff and his research group at the University of Chicago are developing new techniques to study the time-dependent behavior of individual molecules in solution. These methods reveal the motions and interactions of molecules during the course of chemical reactions in a manner that has been previously inaccessible. Single molecule (SM) methods have had enormous impact describing molecular processes that occur on surfaces and in biological processes, but their application to problems in solution-phase chemistry remains a persistent challenge. This project attempts to overcome earlier limitations by using a new high-sensitivity detection strategy, fluorescence-encoded infrared spectroscopy (FEIR), with the goal of using vibrational spectroscopy to track how chemical bonds and molecular contacts evolve in time for single molecules in solution. Students working on this project receive training in a cross-disciplinary setting that provides experience on an array of topics including instrument development, optics and spectroscopy, and chemical dynamics. This training in the Tokmakoff group prepares students for leadership roles in scientific research at academic and national labs, or in high-tech companies.The research supported by this grant builds on recent work by Prof. Tokmakoff and his team demonstrating the single-molecule sensitivity of the FEIR approach using photon correlation spectroscopy (CS). The team is now expanding the capabilities of the FEIR technique using new types of chromophores to target a variety of chemical applications. For example, the research team is developing IR vibrational contrast mechanisms for FEIR-CS that use vibrational frequency shifts as reporters of the chemical dynamics for applications such as site-specific bimolecular binding, protonation and deprotonation reactions, and ion transport through electrolytes. Additionally, the team is working to extend FEIR measurements to measure the dynamic information content of single-molecule photon streams that describe bond-specific histories of individual diffusing and reacting molecules. These research efforts are guided by the overarching goal of building a broadly applicable tool to study chemical dynamics and molecular transport processes in liquids, solutions, and other soft materials. The broader impacts of the project also include the development and dissemination of open-access educational resources.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.