Chemistry of exciplexes. 19. Exciplex-promoted electron transfer in 1-(phenylamino)-3-(9-anthryl)propanes

Light-induced electron transfer in multicomponent systems and polychromophoric molecules is a subject of current interest. In nonpolar media, a photoexcited molecular may react with a ground-state molecule in a specific orientation yielding an exciplex which may be characterized by its fluorescence....

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Bibliographic Details
Published in:Journal of the American Chemical Society 1985-09, Vol.107 (19), p.5531-5532
Main Authors: Yang, Nien Chu C, Gerald, Rex, Wasielewski, Michael R
Format: Article
Language:English
Subjects:
DEACTIVATION
ELECTRON TRANSFER
EXCITATION
GROUND STATES
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
IONS
KINETICS
LIFETIME
MOLECULES
PHOTOCHEMICAL REACTIONS
REACTION INTERMEDIATES
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Summary:Light-induced electron transfer in multicomponent systems and polychromophoric molecules is a subject of current interest. In nonpolar media, a photoexcited molecular may react with a ground-state molecule in a specific orientation yielding an exciplex which may be characterized by its fluorescence. Exciplexes may be deactivated by another ground-state molecule, and it has been suggested that electron transfer may play a role in this deactivation. However, this suggestion was not supported by any direct experimental evidence. A photoexcited molecule may react with a ground-state molecule to undergo electron transfer at an encounter distance yielding a radical ion pair in polar media. These radical ions tend to undergo rapid back electron transfer to revert back to substrates in their ground state or triplet state. In order to convert light energy into chemical energy in an efficient manner, the rate of back electron transfer must be controlled or retarded. In this investigation, the authors examined the reactive intermediates generated from photoexcited polychromophoric systems by kinetic spectroscopy. The compounds used were 1-3 containing an anthryl group as the photoexcited acceptor and one or two dialkylanilino groups as the donor(s). The intermediates derived from these photoexcited compounds, the anthryl radical anion, dialkylanilino radical cation, and anthryl triplet all exhibit well-defined absorption characteristics. This paper demonstrates that an exciplex may undergo electron transfer with another donor molecule in dichloromethane and the lifetimes of ions generated in such a system are substantially longer than the lifetimes of ions from analogous electron transfer in polar media.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00305a038