CAS: Collaborative Research: Photophysics and Electron Transfer Reactivity of Ion Radical Excited States

在化学系化学结构、动力学和机理B(CSDM-B)计划的支持下，德克萨斯大学圣安东尼奥分校化学系的Kirk S.Schanze教授和北乔治亚大学化学系的Aimée Tomlinson教授正在研究带电有机自由基的性质，这些自由基具有作为有机反应和太阳能转换的光敏剂的有用性质。该项目位于有机化学、物理化学和计算化学的交界处，非常适合各级化学科学家的广泛教育。调查人员将利用各自大学的不同人群，让代表不足的学生参与研究的各个方面。这一合作将使从事研究的学生接触到理论和实验之间的反馈回路，从而丰富他们的化学研究项目。该项目试图通过使用密度泛函理论和含时密度泛函理论，通过涉及实验光物理和计算化学的合作方法，提供对控制离子自由基双重态激发态及其电子转移反应性的因素的理解。通过化学还原或氧化的方法制备稳定的各种分子的阴阳离子自由基，然后用皮秒瞬时吸收光谱和荧光光谱方法表征其光物理性质。待确定的关键参数包括二重态激发态的寿命和能量，以及辐射和非辐射衰变速率常数。实验结果将被用来揭示离子自由基双重态激发态的结构-性质关系，具体目的是描述它们的能量和非辐射衰减率之间是否存在能隙定律关联。理论将被用来确定在双激发态能量和寿命方面进行优化的分子系统，从而指导优化的电子转移光敏器件的设计。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。

With support of the Chemical Structure, Dynamics & Mechanisms-B (CSDM-B) Program of the Chemistry Division, Professor Kirk S. Schanze of the Department of Chemistry at the University of Texas at San Antonio, and Professor Aimée Tomlinson of the Department of Chemistry at the University of North Georgia are studying the properties of charged organic radicals with useful properties as photosensitizers for organic reactions and solar energy conversion. The project lies at the interface of organic, physical, and computational chemistry and is well suited for broad education of chemical scientists at all levels. The investigators will leverage the diverse populations at their respective universities to engage underrepresented students in all aspects of the research. This collaboration will provide engaged research students access to the feedback loop between theory and experiment thus enriching their chemical research projects.This project seeks to provide an understanding of the factors that control ion radical doublet excited states and their electron transfer reactivity, through a collaborative approach involving experimental photophysics and computational chemistry using density functional theory and time dependent density functional theory. Stable anion and cation radicals of a variety of molecules will be prepared by chemical reduction or oxidation followed by characterization of their photophysical properties through picosecond transient absorption and fluorescence spectroscopy methods. Key parameters to be determined include the lifetime and energy of the doublet excited state, along with the radiative and non-radiative decay rate constants. The experimental results will be utilized to inform structure-property relationships for the ion radical doublet excited states, with specific aim to delineate whether an energy gap law correlation exists between their energy and non-radiative decay rate. Theory will be used to identify molecular systems that are optimized with respect to doublet excited state energy and lifetime thereby, guiding the design of optimized electron transfer photosensitizers.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.