Photoinduced intramolecular electron transfer in a 2,7-diaminofluorene chromophore decorated with two benzophenone subunits.
An extensive photophysical analysis of a 2,7-bis-(N-4-methoxyphenyl-N-phenylamino)fluorene derivative covalently linked with two benzophenone moieties is presented. A systematic comparison with a model chromophore without benzophenone was performed. For both chromophores, the electronic properties of the ground states are completely equivalent indicating that benzophenone subunits do not exhibit any electronic interaction with the diaminofluorene core. However, at the singlet excited state, the presence of benzophenones induces the occurrence of additional non-radiative de-excitation pathways. Even the intersystem crossing rate is significantly increased with respect to that of the model one. A photoinduced intramolecular electron transfer (PIET) from diaminofluorene to benzophenone subunits is proposed as the most efficient quenching process. At low polar solvent, the emission of an exciplex confirms the PIET process and the occurrence of a partial charge separation between donor and acceptor parts.
Département de Photochimie Générale, UMR CNRS 7525, Université de Haute Alsace, ENSCMu, 3 rue Alfred Werner, 68093, Mulhouse Cedex, France.
Ming
M
Jin
Jean-Pierre
JP
Malval
Fabrice
F
Morlet-Savary
Hélène
H
Chaumeil
Albert
A
Defoin
Pinar
P
Batat
Gediminas
G
Jonusauskas
D016880:Anisotropy; D001577:Benzophenones / Q000737:chemistry*; D004583:Electrons; D005449:Fluorenes / Q000737:chemistry*; D015394:Molecular Structure; D010777:Photochemistry; D013050:Spectrometry, Fluorescence
C541392:2,7-bis-(N-4-methoxyphenyl-N-phenylamino)fluorene; D001577:Benzophenones; D005449:Fluorenes; C047723:benzophenone