Relationship between exciplex fluorescence and electron transfer in radical ion pairs

Ian Gould, Samir Farid, Ralph H. Young

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

The relationship between non-radiative (thermal) return electron transfer within radical ion pairs and the fluorescence spectra of exciplexes is discussed. Those exciplexes in which charge transfer from the donor to the acceptor is nearly complete are essentially contact radical ion pairs, and their fluorescence is a return electron transfer process. In particular, the energy and width of the exciplex fluorescence spectrum are directly related to the electron tranfer reorganization parameters. From the emission spectra of the exciplexes formed by several common acceptors with alkylbenzenes as donors it is found that the reorganization energy for electron transfer decreases with increasing molecular size of the acceptor. The spectra also indicate that in the solvents used in this study, the reorganization parameters with dicyanoanthracene, tetracyanoanthracene, dicyanonaphthalene and dicyanobenzene as acceptors are essentially constant for different alkylbenzene donors. With tetracyanobenzene and, most strikingly, pyromellitic dianhydride, however, the reorganization energy is found to decrease with decreasing oxidation potential of the alkylbenzene donor. The relevance of these observations to the interpretation of the rates of return electron transfer in these system as a function of reaction exothermicity is discussed.

Original languageEnglish (US)
Pages (from-to)133-147
Number of pages15
JournalJournal of Photochemistry and Photobiology, A: Chemistry
Volume65
Issue number1-2
DOIs
StatePublished - Apr 30 1992
Externally publishedYes

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electron transfer
Fluorescence
Ions
fluorescence
Electrons
ions
energy
emission spectra
charge transfer
Charge transfer
oxidation
Oxidation
electrons

ASJC Scopus subject areas

  • Bioengineering
  • Physical and Theoretical Chemistry

Cite this

Relationship between exciplex fluorescence and electron transfer in radical ion pairs. / Gould, Ian; Farid, Samir; Young, Ralph H.

In: Journal of Photochemistry and Photobiology, A: Chemistry, Vol. 65, No. 1-2, 30.04.1992, p. 133-147.

Research output: Contribution to journalArticle

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AB - The relationship between non-radiative (thermal) return electron transfer within radical ion pairs and the fluorescence spectra of exciplexes is discussed. Those exciplexes in which charge transfer from the donor to the acceptor is nearly complete are essentially contact radical ion pairs, and their fluorescence is a return electron transfer process. In particular, the energy and width of the exciplex fluorescence spectrum are directly related to the electron tranfer reorganization parameters. From the emission spectra of the exciplexes formed by several common acceptors with alkylbenzenes as donors it is found that the reorganization energy for electron transfer decreases with increasing molecular size of the acceptor. The spectra also indicate that in the solvents used in this study, the reorganization parameters with dicyanoanthracene, tetracyanoanthracene, dicyanonaphthalene and dicyanobenzene as acceptors are essentially constant for different alkylbenzene donors. With tetracyanobenzene and, most strikingly, pyromellitic dianhydride, however, the reorganization energy is found to decrease with decreasing oxidation potential of the alkylbenzene donor. The relevance of these observations to the interpretation of the rates of return electron transfer in these system as a function of reaction exothermicity is discussed.

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