RUI: Dialing in on the proton: Understanding the role of the proton in photo-induced, proton-coupled electron transfer using tunable model systems

在由化学学部化学结构、动态与机制B项目资助的本科院校研究（RUI）项目中，阿默斯特学院化学系的Elizabeth R. Young教授正在研究模型分子系统中的电子转移。这些模型的灵感来自生物系统，特别是蛋白质，它们非常有效地进行生命所必需的反应。这项研究的结果可能会导致更节能反应的发展，包括将水分解为氢和氧以储存能量，为农业固定氮和减少二氧化碳以减少大气中的温室气体。本科生进行研究，直接参与研究项目的各个阶段：实验设计、物理评价、表征、数据分析和科学写作。学生接受广泛的科学技术培训，学习前沿研究。此外，该项目还加强了马萨诸塞州先锋谷的研究基础设施。质子耦合电子转移（PCET）在自然系统中驱动许多关键反应，包括光合作用的光收集反应。本项目探讨了PCET机理研究中的几个特点。研究了一系列供体和受体体系中酸基团的质子转移能力与电子转移驱动力之间的相互作用，从而直接了解氢键界面如何调节电子转移。需要回答的具体问题包括：在哪个电子转移驱动力范围内，质子转移能力会对观察到的速率产生实质性的影响？质子在界面内的能力是否会导致相同供体和受体之间电子转移速率的显著调制？超分子供体-受体组装模式对耦合和电子转移速率有显著影响吗？这些关于PCET的机理研究提供了重要的见解，让我们了解光如何被用来引发质子和电子协同运动所促进的化学反应。

In this Research at Undergraduate Institutions (RUI) project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Elizabeth R. Young of the Department of Chemistry at Amherst College is studying electron transfer in model molecular systems. These models are inspired by biological systems, specifically proteins, which carry out reactions necessary for life very efficiently. Results of this research could lead to the development of more energy efficient reactions, including splitting water into hydrogen and oxygen for energy storage, nitrogen fixation for agriculture and carbon dioxide reduction to decrease greenhouse gases in the atmosphere. Undergraduate students carry out the research, directly participating in each phase of the research projects: experimental design, physical evaluation, characterization, data analysis and scientific writing. Students are trained in a broad range of scientific techniques and learn cutting-edge research. Additionally, this project enhances the research infrastructure in the Pioneer Valley of Massachusetts. Proton-coupled electron transfer (PCET) drives numerous critical reactions in natural systems, including the light-harvesting reactions of photosynthesis. This project explores several features in the mechanistic study of PCET. The interplay between electron transfer driving force and the proton transfer ability of acid groups in a series of donor and acceptor systems is studied, in order to provide direct insight into how hydrogen-bonded interfaces modulate electron transfer. Specific questions to be answered include: For which electron transfer driving force ranges does the proton transfer ability make a substantial difference in the observed rates? Does the ability of a proton within the interface result in significant modulation in the electron transfer rate between the same donor and acceptor moieties? Does the mode of supramolecular donor-acceptor assembly have a significant impact on coupling and electron transfer rates? These mechanistic studies of PCET provide important insights into how light could be used to initiate chemical reactions that are facilitated by the concerted movement of protons and electrons.