Excitation Energy Transfer and Exchange-Mediated Quartet State Formation in Porphyrin-Trityl Systems

Oliver Nolden, Nico Fleck, Emmaline R. Lorenzo, Michael R. Wasielewski, Olav Schiemann, Peter Gilch, Sabine Richert*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Photogenerated multi-spin systems hold great promise for a range of technological applications in various fields, including molecular spintronics and artificial photosynthesis. However, the further development of these applications, via targeted design of materials with specific magnetic properties, currently still suffers from a lack of understanding of the factors influencing the underlying excited state dynamics and mechanisms on a molecular level. In particular, systematic studies, making use of different techniques to obtain complementary information, are largely missing. This work investigates the photophysics and magnetic properties of a series of three covalently-linked porphyrin-trityl compounds, bridged by a phenyl spacer. By combining the results from femtosecond transient absorption and electron paramagnetic resonance spectroscopies, we determine the efficiencies of the competing excited state reaction pathways and characterise the magnetic properties of the individual spin states, formed by the interaction between the chromophore triplet and the stable radical. The differences observed for the three investigated compounds are rationalised in the context of available theoretical models and the implications of the results of this study for the design of a molecular system with an improved intersystem crossing efficiency are discussed.

Original languageEnglish (US)
Pages (from-to)2683-2691
Number of pages9
JournalChemistry - A European Journal
Volume27
Issue number8
DOIs
StatePublished - Feb 5 2021

Keywords

  • enhanced intersystem crossing
  • excitation energy transfer
  • excited multi-spin systems
  • quartet state formation
  • transient EPR spectroscopy

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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