Time-Resolved Resonance Raman and DFT Study of the Structure and Dynamics of the Photochemistry for Benzophenone in Iso-Propyl Alchol

Abstract

A comparative time-resolved resonance Raman (TR3) spectroscopic and density functional theory (DFT) computational investigation of the structures and dynamics of triplet reaction of benzophenone in the hydrogen-donor solvent of isopropyl alcohol (eq. 1) is presented. Our TR3 results reveal a rapid hydrogen-abstraction (<10 ns) of the benzophenone triplet state (np*) from the isopropyl alcohol solvent leading to formation of a ketyl radical (1) and an associated radical partner (2). Temporal evolution of the TR3 spectra also indicates recombination of the two radical species with a time constant of 1154 ns that forms a coupling product 3 that has a lifetime of about 1170 ns. The structure, major spectral features and identification of 1 and 3 have been determined and confirmed by corresponding DFT calculations. To our knowledge, this is the first time-resolved resonance Raman characterization of the intermediates and dynamics for the photoreaction of benzophenone in isopropyl alcohol.