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[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
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Characterizing Chain Processes in Visible Light Photoredox Catalysis.

Megan A Cismesia1, Tehshik P Yoon1

  • 1Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin, 53706, USA.

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|December 16, 2015
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Summary

Visible light photoredox catalysis using transition metal complexes can involve product-forming chain reactions. Quantum yield and luminescence quenching experiments rapidly estimate chain lengths, aiding mechanistic understanding.

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Area of Science:

  • Photochemistry
  • Organic Synthesis
  • Catalysis

Background:

  • Visible light absorbing transition metal complexes, like Ru(bpy)32+, are potent photocatalysts.
  • Photoredox catalysis has seen renewed interest for organic synthesis.
  • Mechanistic details, especially the role of radical chain processes, remain unclear.

Purpose of the Study:

  • To systematically analyze the involvement of radical chain processes in visible light photoredox reactions.
  • To demonstrate that representative photoredox processes utilize product-forming chain reactions.
  • To establish a rapid method for estimating chain lengths in these reactions.

Main Methods:

  • Quantum yield measurements were performed on three distinct photoredox processes.
  • Luminescence quenching experiments were combined with quantum yield data.
  • A strategy was developed to characterize chain processes.

Main Results:

  • Demonstrated that three representative photoredox processes involve product-forming chain reactions.
  • Showed that combining quantum yield and luminescence quenching rapidly estimates chain lengths.
  • Established a robust and facile strategy for characterizing chain processes.

Conclusions:

  • Visible light photoredox catalysis frequently involves chain reactions.
  • Quantum yield and luminescence quenching offer a rapid and effective method for mechanistic studies.
  • This strategy facilitates the characterization of chain processes in diverse photoredox reactions.