Lubica Klicova, Peter Sebej, Tomas Solomek, Bruno Hellrung, Petr Slavicek, Petr Klan, Dominik Heger, Jakob Wirz,
"Adiabatic Triplet State Tautomerization of p-Hydroxyacetophenone
in Aqueous Solution", J. Phys. Chem. A, 2012 116, 2935-2944.
Abstract: The primary photophysical processes of p-hydroxyacetophenone
(HA) and the ensuing proton transfer
reactions in aqueous solution were investigated by picosecond
pump-probe spectroscopy and nanosecond laser flash
photolysis. Previous studies have led to mutually inconsistent
conclusions. The combined data allow us to rationalize the
excited-state proton transfer processes of HA in terms of a
comprehensive, well-established reaction scheme. Following
fast and quantitative ISC to the triplet state, 3HA*, adiabatic
proton transfer through solvent water simultaneously forms
both the anion, 3A-*, and the quinoid triplet enol tautomer, 3Q*. The latter subsequently equilibrates with its anion 3A-*.
Ionization and tautomerization are likely to compete with the desired release reactions of p-hydroxyphenacyl photoremovable