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

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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.