Elucidating Mechanisms in Visible Light-Driven Photocatalysis Using Time-Resolved Infrared Spectroscopy

(Mentor: Matthias M. Waegele, Assistant Prof. of Chemistry)
Visible light-driven photocatalysis is rapidly emerging as a powerful strategy in organic synthesis for achieving unique bond transformations that are difficult or impossible to access using existing methods. Unfortunately, visible light-driven transformations of organic molecules often suffer from a narrow substrate scope. To date, the development of synthetic protocols heavily relies on the empirically screening for optimal reaction conditions, while the underlying physical mechanisms that limit the structural scope of the feedstock molecules remain largely unexplored. As a result, the mechanistic understanding of photocatalytic transformations are in their infancy. To develop more efficient synthetic strategies, it is essential to understand how the interplay between light absorber, redox catalyst, and reactive substrates gives rise to catalytic activity and selectivity. To this end, we will carry out mechanistic case studies of prototypical photocatalytic systems to reveal how energy- and/or electron-transfer events are temporally related to desired and undesired bond transformations. We will employ time-resolved vibrational spectroscopy as our primary tool of investigation due to its intrinsic structure-selectivity and high time-resolution. A student will participate in spectroscopic measurements and collaborate with organic chemistry groups in the Chemistry Department for the preparation of samples.