Scientific article
Open access

Chiral control of spin-crossover dynamics in Fe(II) complexes

Published inNature chemistry, vol. 14, no. 7, p. 739-745
Publication date2022-05-26
First online date2022-05-26

Iron-based spin-crossover complexes hold tremendous promise as multifunctional switches in molecular devices. However, real-world technological applications require the excited high-spin state to be kinetically stable-a feature that has been achieved only at cryogenic temperatures. Here we demonstrate high-spin-state trapping by controlling the chiral configuration of the prototypical iron(II)tris(4,4′-dimethyl-2,2′-bipyridine) in solution, associated for stereocontrol with the enantiopure Δ-or Λ-enantiomer of tris(3,4,5,6-tetrachlorobenzene-1,2-diolato-κ2O1,O2)phosphorus(V) (P(O2C6Cl4)3- or TRISPHAT) anions. We characterize the high-spin-state relaxation using broadband ultrafast circular dichroism spectroscopy in the deep ultraviolet in combination with transient absorption and anisotropy measurements. We find that the high-spin-state decay is accompanied by ultrafast changes of its optical activity, reflecting the coupling to a symmetry-breaking torsional twisting mode, contrary to the commonly assumed picture. The diastereoselective ion pairing suppresses the vibrational population of the identified reaction coordinate, thereby achieving a fourfold increase of the high-spin-state lifetime. More generally, our results motivate the synthetic control of the torsional modes of iron(II) complexes as a complementary route to manipulate their spin-crossover dynamics.

  • Circular dichroism
  • Excited states
  • Organometallic chemistry
  • Photochemistry
  • Optical spectroscopy
Research group
Citation (ISO format)
OPPERMANN, Malte et al. Chiral control of spin-crossover dynamics in Fe(II) complexes. In: Nature chemistry, 2022, vol. 14, n° 7, p. 739–745. doi: 10.1038/s41557-022-00933-0
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Article (Published version)
Article (Submitted version)
ISSN of the journal1755-4330

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Creation07/05/2022 9:46:00 AM
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