Excimer Formation and Symmetry-Breaking Charge Transfer in Cofacial Perylene Dimers

Rita E. Cook, Brian T. Phelan, Rebecca J. Kamire, Marek B. Majewski, Ryan M. Young, Michael R Wasielewski

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38 Citations (Scopus)

Abstract

The use of multiple chromophores as photosensitizers for catalysts involved in energy-demanding redox reactions is often complicated by electronic interactions between the chromophores. These interchromophore interactions can lead to processes, such as excimer formation and symmetry-breaking charge separation (SB-CS), that compete with efficient electron transfer to or from the catalyst. Here, two dimers of perylene bound either directly or through a xylyl spacer to a xanthene backbone were synthesized to probe the effects of interchromophore electronic coupling on excimer formation and SB-CS using ultrafast transient absorption spectroscopy. Two time constants for excimer formation in the 1-25 ps range were observed in each dimer due to the presence of rotational isomers having different degrees of interchromophore coupling. In highly polar acetonitrile, SB-CS competes with excimer formation in the more weakly coupled isomers followed by charge recombination with τCR = 72-85 ps to yield the excimer. The results of this study of perylene molecular dimers can inform the design of chromophore-catalyst systems for solar fuel production that utilize multiple perylene chromophores. (Figure Presented).

Original languageEnglish
Pages (from-to)1607-1615
Number of pages9
JournalJournal of Physical Chemistry A
Volume121
Issue number8
DOIs
Publication statusPublished - Mar 2 2017

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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