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Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime

Kjær, Kasper Skov LU ; Kaul, Nidhi; Prakash, Om LU ; Chábera, Pavel LU ; Rosemann, Nils W. LU ; Honarfar, Alireza LU ; Gordivska, Olga LU ; Fredin, Lisa A. LU ; Bergquist, Karl-Erik LU and Häggström, Lennart, et al. (2018) In Science
Abstract

Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer (CT) states of most Fe complexes are limited by picosecond or sub-picosecond deactivation through low-lying metal centered (MC) states, resulting in inefficient electron transfer reactivity and complete lack of photoluminescence. Here we show that octahedral coordination of Fe(III) by two mono-anionic facial tris-carbene ligands can suppress such deactivation dramatically. The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is [phenyl(tris(3-methylimidazol-1-ylidene))borate]-, exhibits strong, visible, room temperature photoluminescence with a... (More)

Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer (CT) states of most Fe complexes are limited by picosecond or sub-picosecond deactivation through low-lying metal centered (MC) states, resulting in inefficient electron transfer reactivity and complete lack of photoluminescence. Here we show that octahedral coordination of Fe(III) by two mono-anionic facial tris-carbene ligands can suppress such deactivation dramatically. The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is [phenyl(tris(3-methylimidazol-1-ylidene))borate]-, exhibits strong, visible, room temperature photoluminescence with a 2.0 ns lifetime and 2% quantum yield via spin-allowed transition from a ligand-to-metal charge-transfer (2 LMCT) state to the ground state (2 GS). Reductive and oxidative electron transfer reactions were observed for the2 LMCT state of [Fe(phtmeimb)2]+ in bimolecular quenching studies with methylviologen and diphenylamine.

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Science
publisher
The American Association for the Advancement of Science
external identifiers
  • scopus:85058101425
ISSN
0036-8075
DOI
10.1126/science.aau7160
language
English
LU publication?
yes
id
4042e0d0-0ce0-4e18-ac2d-9bf17afd892a
date added to LUP
2018-12-21 11:43:59
date last changed
2019-01-14 07:40:04
@article{4042e0d0-0ce0-4e18-ac2d-9bf17afd892a,
  abstract     = {<p>Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer (CT) states of most Fe complexes are limited by picosecond or sub-picosecond deactivation through low-lying metal centered (MC) states, resulting in inefficient electron transfer reactivity and complete lack of photoluminescence. Here we show that octahedral coordination of Fe(III) by two mono-anionic facial tris-carbene ligands can suppress such deactivation dramatically. The resulting complex [Fe(phtmeimb)<sub>2</sub>]<sup>+</sup>, where phtmeimb is [phenyl(tris(3-methylimidazol-1-ylidene))borate]<sup>-</sup>, exhibits strong, visible, room temperature photoluminescence with a 2.0 ns lifetime and 2% quantum yield via spin-allowed transition from a ligand-to-metal charge-transfer (<sup>2</sup> LMCT) state to the ground state (<sup>2</sup> GS). Reductive and oxidative electron transfer reactions were observed for the<sup>2</sup> LMCT state of [Fe(phtmeimb)<sub>2</sub>]<sup>+</sup> in bimolecular quenching studies with methylviologen and diphenylamine.</p>},
  author       = {Kjær, Kasper Skov and Kaul, Nidhi and Prakash, Om and Chábera, Pavel and Rosemann, Nils W. and Honarfar, Alireza and Gordivska, Olga and Fredin, Lisa A. and Bergquist, Karl-Erik and Häggström, Lennart and Ericsson, Tore and Lindh, Linnea and Yartsev, Arkady and Styring, Stenbjörn and Huang, Ping and Uhlig, Jens and Bendix, Jesper and Strand, Daniel and Sundström, Villy and Persson, Petter and Lomoth, Reiner and Wärnmark, Kenneth},
  issn         = {0036-8075},
  language     = {eng},
  publisher    = {The American Association for the Advancement of Science},
  series       = {Science},
  title        = {Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime},
  url          = {http://dx.doi.org/10.1126/science.aau7160},
  year         = {2018},
}