Mediating Photochemical Reaction Rates at Lewis Acidic Rare Earths by Selective Energy Loss to 4f-Electron States

Kevin Ruoff, Melissa Gish, Ellen Song, Iskander Douair, Pragati Pandey, Mark Steger, Justin Johnson, Patrick Carroll, Michael Gau, Christopher Chang, Ross Larsen, Andrew Ferguson, Eric Schelter

Research output: Contribution to journalArticlepeer-review

Abstract

Manifesting chemical differences in individual rare earth (RE) element complexes is challenging due to the similar sizes of the tripositive cations and the corelike 4f shell. We disclose a new strategy for differentiating between similarly sized Dy3+ and Y3+ ions through a tailored photochemical reaction of their isostructural complexes in which the f-electron states of Dy3+ act as an energy sink. Complexes RE(hfac)3(NMMO)2 (RE = Dy (2-Dy) and Y (2-Y), hfac = hexafluoroacetylacetonate, and NMMO = N-methylmorpholine-N-oxide) showed variable rates of oxygen atom transfer (OAT) to triphenylphosphine under ultraviolet (UV) irradiation, as monitored by 1H and 19F NMR spectroscopies. Ultrafast transient absorption spectroscopy (TAS) identified the excited state(s) responsible for the photochemical OAT reaction or lack thereof. Competing sensitization pathways leading to excited-state deactivation in 2-Dy through energy transfer to the 4f electron manifold ultimately slows the OAT reaction at this metal cation. The measured rate differences between the open-shell Dy3+ and closed-shell Y3+ complexes demonstrate that using established principles of 4f ion sensitization may deliver new, selective modalities for differentiating the RE elements that do not depend on cation size.

Original languageAmerican English
Pages (from-to)16374-16382
Number of pages9
JournalJournal of the American Chemical Society
Volume145
Issue number30
DOIs
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-84574

Keywords

  • oxygen atom transfer
  • rare earth photochemistry
  • rare earth photophysics
  • ultrafast spectroscopy

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