Excited doublet states of electrochemically generated aromatic imide and diimide radical anions

David Gosztola, Mark P. Niemczyk, Walter Svec, Aaron S. Lukas, Michael R. Wasielewski

Research output: Contribution to journalArticle

413 Citations (Scopus)

Abstract

The radical anions of aromatic diimides have been implicated recently in a wide variety of photochemical electron transfer reactions. Photoexcitation of these radical anions produces powerfully reducing species. Yet, the properties of the n excited doublet states of these organic radical anions remain obscure. The radical anions of three aromatic imides with increasingly larger n systems, N-(2,5-di-te/-?-butylphenyl)phthalimide, 1, Ar-(2,5-di-rert-butylphenyl)-l,8-naphthalimide, 2, and N-(2,5-di-/err-butylphenyl)perylene-3,4-dicarboximide, 3, as well as the three corresponding aromatic diimides, N,W-bis(2,5-di-Yer?-butylphenyl)pyromellitimide, 4a, N,N′-bis(2,5-di-/ert-butylphenyl)-naphthalene-l,8:4,5-tetracarboxydiimide, 5a, and N,N′-bis(2,5-di-tertbutylphenyl)perylene-3,4:9,10-tetracarboxydiimide, 6, were produced by electrochemical reduction of the neutral molecules in an optically transparent thin layer electrochemical cell. The radical anions of these imides and diimides all exhibit intense visible and weaker near-IR absorption bands corresponding to their D0 → Dn transitions. Excited states of the radical anions were generated by subpicosecond excitation into these absorption -bands. Excitation of 1-- and 2- resulted in decomposition of these radical anions, whereas excitation of 3'-6- yielded transient spectra of their D] -Dn transitions and the lifetimes of D1. The lifetimes of the DI excited states of the radical anions of 3-6'- are all less than 600 ps and increase as the D0-D1 energy gap increases. These results impose design constraints on the use of these excited radical anions as electron donors -in electron-transfer systems targeted toward molecular electronics and solar energy conversion.

Original languageEnglish
Pages (from-to)6545-6551
Number of pages7
JournalJournal of Physical Chemistry A
Volume104
Issue number28
DOIs
Publication statusPublished - Jul 20 2000

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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