Intersystem crossing mediated by photoinduced intramolecular charge transfer: Julolidine - Anthracene molecules with perpendicular π systems

Zachary E.X. Dance, Sarah M. Mickley, Thea M. Wilson, Annie Butler Ricks, Amy M. Scott, Mark A. Ratner, Michael R. Wasielewski

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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 π 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 (θ1) between their π 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-dimethyrjulolidine and find that fixing θ1 ≅ 90° 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.

Original languageEnglish
Pages (from-to)4194-4201
Number of pages8
JournalJournal of Physical Chemistry A
Issue number18
Publication statusPublished - May 8 2008


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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