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Yanmei He. Portrait.

Yanmei He

Postdoctoral fellow

Yanmei He. Portrait.

Reversible excited state electron transfer in an acceptor-acceptor hetero dyad

Author

  • Jesper Dahl Jensen
  • Shayan Louie
  • Yanmei He
  • Junsheng Chen
  • Colin Nuckolls
  • Bo W. Laursen

Summary, in English

In this manuscript, we create a new hetero dyad consisting of two electron acceptors with nearly isoenergetic HOMO and LUMO levels, namely perylene diimide (PDI) and aza dioxa triangulenium (ADOTA). This dyad system displays an unusual and reversible excited state electron transfer process. Upon excitation, the dyad shows complete energy transfer from the locally excited PDI to the ADOTA moiety in ∼1 ps, followed by photoinduced electron transfer (PET), forming oxidized PDI and reduced ADOTA. While this PET process is fast (kPET≈ 150 ps), the reversibility establishes an equilibrium between fluorescent locally excited ADOTA and the dark charge shifted PET state. We investigate the formation of and decay from this unusual reversible excited state electron transfer system by fs transient absorption and time-resolved fluorescence spectroscopy in different solvent mixtures because the solvent modulates the deactivation rate of the PET state. Electrochemistry confirms that both the local HOMOs and LUMOs of PDI and ADOTA are nearly isoenergetic but can be shifted by solvent polarity, which elucidates the reason for the unusual reversible electron transfer process and its sensitivity to the solvent. We further investigate near degeneracy of the LUMOs through spectroscopy of the chemically reduced dyad. We find that there is an equilibrium between the reduction of the cationic ADOTA to a neutral dyad, which is favored in DCM. However, in DMF, we find reduction of the PDI leads to formation of the zwitterionic dyad.

Department/s

  • Chemical Physics
  • NanoLund: Centre for Nanoscience
  • LTH Profile Area: Nanoscience and Semiconductor Technology
  • LU Profile Area: Light and Materials

Publishing year

2025-04-23

Language

English

Pages

9525-9534

Publication/Series

Chemical Science

Volume

16

Issue

21

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Atom and Molecular Physics and Optics
  • Chemical Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 2041-6520