"Inverted" Solvent Effect on Charge Transfer in the Excited State.
Faster in cyclohexane than in acetonitrile is the fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by amines and sulfides. Although this photoreaction is induced by charge transfer (CT; see picture) and exciplexes are formed, the increase in the dipole moment of the exciplex is not large enough to offset the solvent stabilization of the excited reactants, and an "inverted" solvent effect results.
Nau
WM
Departement Chemie der Universität, Klingelbergstrasse 80, CH-4056 Basel (Switzerland).
Pischel
U