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Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2'-bipyridine)2(CN)2]

Kjær, Kasper S. LU ; Zhang, Wenkai; Alonso-Mori, Roberto; Bergmann, Uwe; Chollet, Matthieu; Hadt, Ryan G.; Hartsock, Robert W.; Harlang, Tobias LU ; Kroll, Thomas and Kubiček, Katharina, et al. (2017) In Structural Dynamics 4(4).
Abstract

We have used femtosecond resolution UV-visible and Kβ x-ray emission spectroscopy to characterize the electronic excited state dynamics of [Fe(bpy)2(CN)2], where bpy=2,20-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,20-bipyridine radical anion, provides a robust marker for the MLCT excited state, while the transient Kβ x-ray emission spectra provide a clear measure of intermediate and high spin metal-centered excited states. From these measurements, we conclude that the MLCT state of [Fe(bpy)2(CN)2] undergoes ultrafast spin crossover to a metalcentered quintet excited state through a short lived... (More)

We have used femtosecond resolution UV-visible and Kβ x-ray emission spectroscopy to characterize the electronic excited state dynamics of [Fe(bpy)2(CN)2], where bpy=2,20-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,20-bipyridine radical anion, provides a robust marker for the MLCT excited state, while the transient Kβ x-ray emission spectra provide a clear measure of intermediate and high spin metal-centered excited states. From these measurements, we conclude that the MLCT state of [Fe(bpy)2(CN)2] undergoes ultrafast spin crossover to a metalcentered quintet excited state through a short lived metal-centered triplet transient species. These measurements of [Fe(bpy)2(CN)2] complement prior measurement performed on [Fe(bpy)3]2+ and [Fe(bpy)(CN)4]2- in dimethylsulfoxide solution and help complete the chemical series [Fe(bpy)N(CN)6-2N]2N-4, whereN=1-3. The measurements confirm that simple ligand modifications can significantly change the relaxation pathways and excited state lifetimes and support the further investigation of light harvesting and photocatalytic applications of 3d transition metal complexes.

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published
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Structural Dynamics
volume
4
issue
4
publisher
American Institute of Physics
external identifiers
  • scopus:85020295485
ISSN
2329-7778
DOI
10.1063/1.4985017
language
English
LU publication?
yes
id
5b0387a5-d269-47b4-b60c-e9b5b37fa02c
date added to LUP
2017-06-26 14:49:55
date last changed
2017-06-26 14:49:55
@article{5b0387a5-d269-47b4-b60c-e9b5b37fa02c,
  abstract     = {<p>We have used femtosecond resolution UV-visible and Kβ x-ray emission spectroscopy to characterize the electronic excited state dynamics of [Fe(bpy)2(CN)2], where bpy=2,20-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,20-bipyridine radical anion, provides a robust marker for the MLCT excited state, while the transient Kβ x-ray emission spectra provide a clear measure of intermediate and high spin metal-centered excited states. From these measurements, we conclude that the MLCT state of [Fe(bpy)<sub>2</sub>(CN)<sub>2</sub>] undergoes ultrafast spin crossover to a metalcentered quintet excited state through a short lived metal-centered triplet transient species. These measurements of [Fe(bpy)<sub>2</sub>(CN)<sub>2</sub>] complement prior measurement performed on [Fe(bpy)<sub>3</sub>]<sup>2+</sup> and [Fe(bpy)(CN)<sub>4</sub>]<sup>2-</sup> in dimethylsulfoxide solution and help complete the chemical series [Fe(bpy)N(CN)<sub>6-2N</sub>]<sup>2N-4</sup>, whereN=1-3. The measurements confirm that simple ligand modifications can significantly change the relaxation pathways and excited state lifetimes and support the further investigation of light harvesting and photocatalytic applications of 3d transition metal complexes.</p>},
  articleno    = {044030},
  author       = {Kjær, Kasper S. and Zhang, Wenkai and Alonso-Mori, Roberto and Bergmann, Uwe and Chollet, Matthieu and Hadt, Ryan G. and Hartsock, Robert W. and Harlang, Tobias and Kroll, Thomas and Kubiček, Katharina and Lemke, Henrik T. and Liang, Huiyang W. and Liu, Yizhu and Nielsen, Martin M. and Robinson, Joseph S. and Solomon, Edward I. and Sokaras, Dimosthenis and van Driel, Tim B and Weng, Tsu-Chien and Zhu, Diling and Persson, Petter and Wärnmark, Kenneth and Sundström, Villy and Gaffney, Kelly J.},
  issn         = {2329-7778},
  language     = {eng},
  month        = {07},
  number       = {4},
  publisher    = {American Institute of Physics},
  series       = {Structural Dynamics},
  title        = {Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2'-bipyridine)<sub>2</sub>(CN)<sub>2</sub>]},
  url          = {http://dx.doi.org/10.1063/1.4985017},
  volume       = {4},
  year         = {2017},
}