Quenching of the Perylene Fluorophore by Stable Nitroxide Radical-Containing Macromolecules

Thomas Gennett, Wade Braunecker, Andrew Ferguson, Ross Larsen, Barbara Hughes, Travis Kemper

Research output: Contribution to journalArticlepeer-review

25 Scopus Citations

Abstract

Stable nitroxide radical bearing organic polymer materials are attracting much attention for their application as next generation energy storage materials. A greater understanding of the inherent charge transfer mechanisms in such systems will ultimately be paramount to further advancements in the understanding of both intrafilm and interfacial ion- and electron-transfer reactions. This work is focused on advancing the fundamental understanding of these dynamic charge transfer properties by exploiting the fact that these species are efficient fluorescence quenchers. We systematically incorporated fluorescent perylene dyes into solutions containing the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical and controlled their interaction by binding the TEMPO moiety into macromolecules with varying morphologies (e.g., chain length, density of radical pendant groups). In the case of the model compound, 4-oxo-TEMPO, quenching of the perylene excited state was found to be dominated by a dynamic (collisional) process, with a contribution from an apparent static process that is described by an ∼2 nm quenching sphere of action. When we incorporated the TEMPO unit into a macromolecule, the quenching behavior was altered significantly. The results can be described by using two models: (A) a collisional quenching process that becomes less efficient, presumably due to a reduction in the diffusion constant of the quenching entity, with a quenching sphere of action similar to 4-oxo-TEMPO or (B) a collisional quenching process that becomes more efficient as the radius of interaction grows larger with increasing oligomer length. This is the first study that definitively illustrates that fluorophore quenching by a polymer system cannot be explained using merely a classical Stern-Volmer approach but rather necessitates a more complex model.

Original languageAmerican English
Pages (from-to)12541-12548
Number of pages8
JournalJournal of Physical Chemistry B
Volume118
Issue number43
DOIs
StatePublished - 30 Oct 2014

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-61842

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