Event

Title: Proton Dynamics in the Excited States: From Model Systems to Applications

Abstract : Many excited state redox processes are founded on two equally important fundamental charge transfer processes – electron transfer and proton transfer. Understanding the dynamics of both electrons and protons in the excited states, and particularly their coupled motion, is necessary to optimize photocatalytic reactions. In this talk, several new excited state proton dynamics phenomena, including photobasicity, photoinduced proton conductivity, and photoinduced modulation of hydrogen bonds in the solid state will be introduced. Both the fundamental physics and chemistry of such phenomena, and our work towards bringing them closer to applications will be discussed. Steady state and ultrafast spectroscopy results will be shown that unravel the thermodynamic origin and kinetic subtleties of photobasicity, which is a large jump in the pKa of a molecule upon photoexcitation. Schemes for incorporating them as functional elements in catalysts for proton removal will be described. A second set of results will show signatures of coupling between excited state charge transfer and hydrogen bonding in an organic crystal. The broader relevance of these observations to functional organic solids will be discussed. Finally, experiments that relate excited state proton transfer to bulk proton transport will be described along with their relevance for protonic devices