Photoinitiated long-lived charge separation with near-unity quantum yield in donor-acceptor1-acceptor2 systems for artificial photosynthesis

Won Sik Han, Brad S. Veldkamp, Scott M. Dyar, Samuel W. Eaton, Michael R. Wasielewski

Research output: Contribution to journalArticle

Abstract

We report the synthesis and photophysical characterization of isomeric donor-acceptor1-acceptor2 (D-A1-A2) triads each comprising a perylene donor (D) connected by a xylene bridge to a naphthalene-1,8-dicarboximide primary acceptor (NMI, A1) that is, in turn, covalently linked to a naphthalene-1,4:5,8-bis(dicarboximide) secondary acceptor (NDI, A2) through a benzene ring at its ortho, meta or para positions (Per-Xy-NMI-x-NDI). Selective photoexcitation of Per produces both Per+• and NDI‒• simultaneously with time constants of ∼50 ps in benzonitrile and ∼80 ps in toluene with a >98% yield. This is much faster than expected for single-step electron transfer from 1*Per to NDI and is consistent with a two-step mechanism, 1*Per-Xy-NMI-x-NDI → Per+•-Xy-NMI‒•-x-NDI → Per+•-Xy-NMI-x-NDI‒•, in which the second step is much faster than the first step. In addition, preserving long-lived charge separation in these systems is found to depend on inhibiting charge recombination by a triplet radical ion pair recombination pathway.

Original languageEnglish
Pages (from-to)4925-4935
Number of pages11
JournalTetrahedron
Volume73
Issue number33
DOIs
Publication statusPublished - Jan 1 2017

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Keywords

  • Donor-acceptor
  • Photochemistry
  • Radical pairs
  • Transient absorption spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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