Fluorescence-Encoded Infrared Spectroscopy for Single-Molecule Chemical Dynamics

在化学系化学结构、动力学和机理 A (CSDM-A) 项目的支持下，芝加哥大学的 Andrei Tokmakoff 教授和他的研究小组正在开发新技术来研究溶液中单个分子的时间依赖性行为。这些方法以以前无法实现的方式揭示了化学反应过程中分子的运动和相互作用。 单分子（SM）方法对描述表面和生物过程中发生的分子过程产生了巨大影响，但它们在溶液相化学问题中的应用仍然是一个持续的挑战。该项目试图通过使用新的高灵敏度检测策略——荧光编码红外光谱（FEIR）来克服早期的局限性，目标是利用振动光谱来跟踪溶液中单分子的化学键和分子接触如何及时演化。 从事该项目的学生接受跨学科培训，提供一系列主题的经验，包括仪器开发、光学和光谱学以及化学动力学。 Tokmakoff 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。这笔资助支持的研究建立在 Tokmakoff 教授及其团队最近的工作基础上，该工作展示了使用光子相关光谱 (CS) 的 FEIR 方法的单分子灵敏度。该团队目前正在使用新型发色团扩展 FEIR 技术的功能，以适应各种化学应用。例如，研究团队正在开发 FEIR-CS 的红外振动对比机制，该机制使用振动频移作为化学动力学的报告者，用于位点特异性双分子结合、质子化和去质子化反应以及通过电解质的离子传输等应用。此外，该团队正在努力扩展 FEIR 测量，以测量单分子光子流的动态信息内容，这些信息描述了单个扩散和反应分子的键特定历史。这些研究工作的总体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放获取教育资源的开发和传播。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值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.