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Competing dynamics of intramolecular deactivation and bimolecular charge transfer processes in luminescent Fe(iii) N-heterocyclic carbene complexes

Rosemann, Nils W. LU ; Lindh, Linnea LU orcid ; Bolaño Losada, Iria LU ; Kaufhold, Simon LU orcid ; Prakash, Om LU ; Ilic, Aleksandra LU orcid ; Schwarz, Jesper LU ; Wärnmark, Kenneth LU ; Chábera, Pavel LU and Yartsev, Arkady LU orcid , et al. (2023) In Chemical Science 14(13). p.3569-3579
Abstract

Steady state and ultrafast spectroscopy on [FeIII(phtmeimb)2]PF6 (phtmeimb = phenyl(tris(3-methylimidazol-2-ylidene))borate) was performed over a broad range of temperatures. The intramolecular deactivation dynamics of the luminescent doublet ligand-to-metal charge-transfer (2LMCT) state was established based on Arrhenius analysis, indicating the direct deactivation of the 2LMCT state to the doublet ground state as a key limitation to the lifetime. In selected solvent environments photoinduced disproportionation generating short-lived Fe(iv) and Fe(ii) complex pairs that subsequently undergo bimolecular recombination was observed. The forward charge separation process is found to be... (More)

Steady state and ultrafast spectroscopy on [FeIII(phtmeimb)2]PF6 (phtmeimb = phenyl(tris(3-methylimidazol-2-ylidene))borate) was performed over a broad range of temperatures. The intramolecular deactivation dynamics of the luminescent doublet ligand-to-metal charge-transfer (2LMCT) state was established based on Arrhenius analysis, indicating the direct deactivation of the 2LMCT state to the doublet ground state as a key limitation to the lifetime. In selected solvent environments photoinduced disproportionation generating short-lived Fe(iv) and Fe(ii) complex pairs that subsequently undergo bimolecular recombination was observed. The forward charge separation process is found to be temperature-independent with a rate of ∼1 ps−1. Subsequent charge recombination takes place in the inverted Marcus region with an effective barrier of 60 meV (483 cm−1). Overall, the photoinduced intermolecular charge separation efficiently outcompetes the intramolecular deactivation over a broad range of temperatures, highlighting the potential of [FeIII(phtmeimb)2]PF6 to perform photocatalytic bimolecular reactions.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Chemical Science
volume
14
issue
13
pages
11 pages
publisher
Royal Society of Chemistry
external identifiers
  • pmid:37006696
  • scopus:85150205280
ISSN
2041-6520
DOI
10.1039/d2sc05357h
language
English
LU publication?
yes
id
ba644e37-0dbd-4a6d-9baf-bf9a8dcd3bdf
date added to LUP
2023-07-05 15:41:50
date last changed
2024-04-20 00:17:13
@article{ba644e37-0dbd-4a6d-9baf-bf9a8dcd3bdf,
  abstract     = {{<p>Steady state and ultrafast spectroscopy on [Fe<sup>III</sup>(phtmeimb)<sub>2</sub>]PF<sub>6</sub> (phtmeimb = phenyl(tris(3-methylimidazol-2-ylidene))borate) was performed over a broad range of temperatures. The intramolecular deactivation dynamics of the luminescent doublet ligand-to-metal charge-transfer (<sup>2</sup>LMCT) state was established based on Arrhenius analysis, indicating the direct deactivation of the <sup>2</sup>LMCT state to the doublet ground state as a key limitation to the lifetime. In selected solvent environments photoinduced disproportionation generating short-lived Fe(iv) and Fe(ii) complex pairs that subsequently undergo bimolecular recombination was observed. The forward charge separation process is found to be temperature-independent with a rate of ∼1 ps<sup>−1</sup>. Subsequent charge recombination takes place in the inverted Marcus region with an effective barrier of 60 meV (483 cm<sup>−1</sup>). Overall, the photoinduced intermolecular charge separation efficiently outcompetes the intramolecular deactivation over a broad range of temperatures, highlighting the potential of [Fe<sup>III</sup>(phtmeimb)<sub>2</sub>]PF<sub>6</sub> to perform photocatalytic bimolecular reactions.</p>}},
  author       = {{Rosemann, Nils W. and Lindh, Linnea and Bolaño Losada, Iria and Kaufhold, Simon and Prakash, Om and Ilic, Aleksandra and Schwarz, Jesper and Wärnmark, Kenneth and Chábera, Pavel and Yartsev, Arkady and Persson, Petter}},
  issn         = {{2041-6520}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{13}},
  pages        = {{3569--3579}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Chemical Science}},
  title        = {{Competing dynamics of intramolecular deactivation and bimolecular charge transfer processes in luminescent Fe(iii) N-heterocyclic carbene complexes}},
  url          = {{http://dx.doi.org/10.1039/d2sc05357h}},
  doi          = {{10.1039/d2sc05357h}},
  volume       = {{14}},
  year         = {{2023}},
}