Femtosecond studies of double proton transfer in photoexcited [2,2’-bipyridyl]-3,3’-diol in solution

Double proton transfer dynamics of [2,2’-bipyridyl]-3,3’-diol in its photoexcited state is studied by means of femtosecond fluorescence upconversion spectroscopy. The measurements reveal very fast fluorescence anisotropy decay components, with typical times of ∼200 fs and 10 ps. The short-living (∼200 fs) component is attributed to di-enol tautomer emission; the 10 ps component is characteristic of the mono-keto to di-keto tautomer conversion.