Intersystem crossing mediated by photoinduced intramolecular charge transfer: julolidine-anthracene molecules with perpendicular pi systems.
Time-resolved electron paramagnetic resonance studies show that the primary mechanism of triplet formation following photoexcitation of julolidine-anthracene molecules linked by a single bond and having perpendicular pi systems is a spin-orbit, charge-transfer intersystem crossing mechanism (SOCT-ISC). This mechanism depends on the degree of charge transfer from julolidine to anthracene, the dihedral angle (theta1) between their pi systems, and the magnitude of the electronic coupling between julolidine and anthracene. We compare 4-(9-anthracenyl)-julolidine with the more sterically encumbered 4-(9-anthracenyl)-3,5-dimethyljulolidine and find that fixing theta1 congruent with 90 degrees serves to enhance SOCT-ISC by increasing the change in orbital angular momentum accompanying charge transfer. Given that the requirements for the SOCT-ISC mechanism are quite general, we expect it to occur in a variety of electron donor-acceptor systems.
Dance
Zachary E X
ZE
Department of Chemistry, Argonne-Northwestern Solar Energy Research (ANSER) Center, and International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208-3113, USA.
Mickley
Sarah M
SM
Wilson
Thea M
TM
Ricks
Annie Butler
AB
Scott
Amy M
AM
Ratner
Mark A
MA
Wasielewski
Michael R
MR