Triplet state formation in photoexcited slip-stacked perylene-3,4

9,10- bis(dicarboximide) dimers on a xanthene scaffold

Kelly M. Lefler, Kristen E. Brown, Walter A. Salamant, Scott M. Dyar, Kathryn E. Knowles, Michael R Wasielewski

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Two covalent perylene-3,4:9,10-bis(dicarboximide) (PDI) dimers in which the PDI molecules are attached to a xanthene (Xan) scaffold in which the long axes of the two π-π stacked PDI molecules are slipped by 4.3 and 7.9 Å were prepared. These dimers are designed to mimic J-aggregates and provide insights into the photophysics of triplet state formation in PDI aggregates that target organic electronics. Using ultrafast transient absorption and stimulated Raman spectroscopy, the mechanism of 3PDI formation was found to depend strongly on a competition between the rate of Xan•+- PDI•- formation involving the spacer group and the rate of excimer-like state formation. Which mechanism is favored depends on the degree of electronic coupling between the two PDI molecules and/or solvent polarity. Singlet exciton fission to produce 3PDI does not compete kinetically with these processes. The excimer-like state decays relatively slowly with τ = 28 ns to produce 3PDI, while charge recombination of Xan •+-PDI•- yields 3PDI more than an order of magnitude faster. The perpendicular orientation between the π orbitals of PDI and the Xan bridge provides a large enough orbital angular momentum change to greatly increase the intersystem crossing rate via Xan •+-PDI•-3PDI charge recombination. These results highlight the importance of understanding inter-chromophore electronic coupling in a wide range of geometries as well as the active role that molecular spacers can play in the photophysics of covalent models for self-assembled chromophore aggregates.

Original languageEnglish
Pages (from-to)10333-10345
Number of pages13
JournalJournal of Physical Chemistry A
Volume117
Issue number40
DOIs
Publication statusPublished - Oct 10 2013

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Xanthenes
Perylene
Scaffolds
Dimers
atomic energy levels
slip
dimers
excimers
spacers
chromophores
Chromophores
electronics
Molecules
molecules
orbitals
Angular momentum
fission
polarity
angular momentum
Raman spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Triplet state formation in photoexcited slip-stacked perylene-3,4 : 9,10- bis(dicarboximide) dimers on a xanthene scaffold. / Lefler, Kelly M.; Brown, Kristen E.; Salamant, Walter A.; Dyar, Scott M.; Knowles, Kathryn E.; Wasielewski, Michael R.

In: Journal of Physical Chemistry A, Vol. 117, No. 40, 10.10.2013, p. 10333-10345.

Research output: Contribution to journalArticle

Lefler, Kelly M. ; Brown, Kristen E. ; Salamant, Walter A. ; Dyar, Scott M. ; Knowles, Kathryn E. ; Wasielewski, Michael R. / Triplet state formation in photoexcited slip-stacked perylene-3,4 : 9,10- bis(dicarboximide) dimers on a xanthene scaffold. In: Journal of Physical Chemistry A. 2013 ; Vol. 117, No. 40. pp. 10333-10345.
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