Singlet-singlet annihilation leading to a charge-transfer intermediate in chromophore-end-capped pentaphenylenes.
The excited-state properties of two peryleneimide chromophore end-capped pentaphenylene compounds were investigated in detail using femtosecond transient absorption and single-photon timing experiments. Singlet-singlet annihilation was found to promote one chromophore into a higher excited state and results in the formation of an ultra-short-living intermediate charge-transfer (CT) state in the S(n)-S(1) deactivation pathway. In low-polarity solvents, this CT state is found to be energetically higher than the first excited state and thus cannot be populated via one-photon excitation. The observed CT state decays with a time constant of about 1 ps to form the lowest singlet excited state. These results demonstrate the potential use of the singlet-singlet annihilation as a novel tool in studying reactions occurring in states that are energetically above the S(1).
Fron
Eduard
E
Department of Chemistry, Katholieke Universiteit Leuven, Belgium.
Schweitzer
Gerd
G
Jacob
Josemon
J
Van Vooren
Antoine
A
Beljonne
David
D
Müllen
Klaus
K
Hofkens
Johan
J
Van der Auweraer
Mark
M
De Schryver
Frans C
FC