CAREER:Single-Molecule Spectroscopy as a Mechanistic Tool for Studying Catalyst Reaction Dynamics

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

This award, funded by the Chemical Structure, Dynamics, and Mechanisms-B Program of the Division of Chemistry, will enable Professor Randall H. Goldsmith of the University of Wisconsin Madison to develop and apply tools that enable the observation of unsynchronized chemical dynamics of individual molecular catalysts under turnover conditions. These methods will enable determination of the kinetics of formation and depletion of transient intermediates and temporal fluctuations of catalyst behavior, including shifting rate constants and enantioselectivity. The impact of these microscopic behaviors on bulk reaction dynamics will be explored. Measurements will be made via time-resolved fluorescence microscopy. Fluorophore design, chemical synthesis, and fabrication and deployment of plasmonic nanostructures are critical elements of this approach. Taken together, these activities will allow determination of a chronology of the molecular dynamics of catalysis that will add new insights on reaction mechanism and guide strategies for future catalyst development. Underneath all macroscopic observations that humans can make in everyday life is a churning, vibrant, and dynamic world at the microscopic level of single molecules. By making measurements on single molecules, this proposal endeavors to remove the disconnect between the macro- and micro-world for two purposes. First, the chaotic nature of single molecules hides molecular behavior that has important consequences for industrially useful chemical reactions. Revealing the molecular dynamics of individual catalyst molecules, molecules that enable challenging chemical reactions, will allow greater understanding of their mode of operation, leading the way to the design of new and more effective catalysts and cheaper and "greener" chemistry. Second, removing this disconnect has important consequences for chemical education, as understanding chemical behavior on the macro-scale flows naturally from understanding chemistry at the micro-scale. Few educational experiments exist that can allow students and non-scientists to truly "see" single molecules. This proposal contains a closely integrated outreach activity to build a robust and portable microscope that will allow users to see single molecules with the naked eye. This educational tool will be built and used for new chemical education initiatives in museums and schools, including those with large components of students under-represented in science and technology careers.