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

Kasper Skov Kjær, Wenkai Zhang, Roberto Alonso-Mori, Uwe Bergmann, Matthieu Chollet, Ryan G. Hadt, Robert W. Hartsock, Tobias C. B. Harlang, Thomas Kroll, Katharina Kubiček, Henrik T. Lemke, Huiyang W. Liang, Yizhu Liu, Martin Meedom Nielsen, Joseph S. Robinson, Edward I. Solomon, Dimosthenis Sokaras, Tim B. van Driel, Tsu-Chien Weng, Diling Zhu & 4 others Petter Persson, Kenneth Wärnmark, Villy Sundström, Kelly J. Gaffney

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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=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-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 metal-centered 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, where N = 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.
Original languageEnglish
Article number044030
JournalStructural Dynamics
Volume4
Issue number4
ISSN2329-7778
DOIs
Publication statusPublished - 2017

Bibliographical note

All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Keywords

  • Monte Carlo methods
  • Emission spectra
  • Absorption spectra
  • Excited states
  • Spin crossover

Cite this

Kjær, K. S., Zhang, W., Alonso-Mori, R., Bergmann, U., Chollet, M., Hadt, R. G., ... Gaffney, K. J. (2017). Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]. Structural Dynamics, 4(4), [044030]. https://doi.org/10.1063/1.4985017
Kjær, Kasper Skov ; Zhang, Wenkai ; Alonso-Mori, Roberto ; Bergmann, Uwe ; Chollet, Matthieu ; Hadt, Ryan G. ; Hartsock, Robert W. ; Harlang, Tobias C. B. ; Kroll, Thomas ; Kubiček, Katharina ; Lemke, Henrik T. ; Liang, Huiyang W. ; Liu, Yizhu ; Nielsen, Martin Meedom ; Robinson, Joseph S. ; Solomon, Edward I. ; Sokaras, Dimosthenis ; van Driel, Tim B. ; Weng, Tsu-Chien ; Zhu, Diling ; Persson, Petter ; Wärnmark, Kenneth ; Sundström, Villy ; Gaffney, Kelly J. / Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]. In: Structural Dynamics. 2017 ; Vol. 4, No. 4.
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title = "Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]",
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=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-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 metal-centered 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, where N = 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.",
keywords = "Monte Carlo methods, Emission spectra, Absorption spectra, Excited states, Spin crossover",
author = "Kj{\ae}r, {Kasper Skov} and Wenkai Zhang and Roberto Alonso-Mori and Uwe Bergmann and Matthieu Chollet and Hadt, {Ryan G.} and Hartsock, {Robert W.} and Harlang, {Tobias C. B.} and Thomas Kroll and Katharina Kubiček and Lemke, {Henrik T.} and Liang, {Huiyang W.} and Yizhu Liu and Nielsen, {Martin Meedom} and Robinson, {Joseph S.} and Solomon, {Edward I.} and Dimosthenis Sokaras and {van Driel}, {Tim B.} and Tsu-Chien Weng and Diling Zhu and Petter Persson and Kenneth Wärnmark and Villy Sundström and Gaffney, {Kelly J.}",
note = "All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license",
year = "2017",
doi = "10.1063/1.4985017",
language = "English",
volume = "4",
journal = "Structural Dynamics",
issn = "2329-7778",
publisher = "AAPM - American Association of Physicists in Medicine",
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Kjær, KS, Zhang, W, Alonso-Mori, R, Bergmann, U, Chollet, M, Hadt, RG, Hartsock, RW, Harlang, TCB, Kroll, T, Kubiček, K, Lemke, HT, Liang, HW, Liu, Y, Nielsen, MM, Robinson, JS, Solomon, EI, Sokaras, D, van Driel, TB, Weng, T-C, Zhu, D, Persson, P, Wärnmark, K, Sundström, V & Gaffney, KJ 2017, 'Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]', Structural Dynamics, vol. 4, no. 4, 044030. https://doi.org/10.1063/1.4985017

Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]. / Kjær, Kasper Skov; Zhang, Wenkai; Alonso-Mori, Roberto; Bergmann, Uwe; Chollet, Matthieu; Hadt, Ryan G.; Hartsock, Robert W.; Harlang, Tobias C. B.; Kroll, Thomas; Kubiček, Katharina; Lemke, Henrik T.; Liang, Huiyang W.; Liu, Yizhu; Nielsen, Martin Meedom; Robinson, Joseph S.; Solomon, Edward I.; Sokaras, Dimosthenis; van Driel, Tim B.; Weng, Tsu-Chien; Zhu, Diling; Persson, Petter; Wärnmark, Kenneth; Sundström, Villy; Gaffney, Kelly J.

In: Structural Dynamics, Vol. 4, No. 4, 044030, 2017.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine)2(CN)2]

AU - Kjær, Kasper Skov

AU - Zhang, Wenkai

AU - Alonso-Mori, Roberto

AU - Bergmann, Uwe

AU - Chollet, Matthieu

AU - Hadt, Ryan G.

AU - Hartsock, Robert W.

AU - Harlang, Tobias C. B.

AU - Kroll, Thomas

AU - Kubiček, Katharina

AU - Lemke, Henrik T.

AU - Liang, Huiyang W.

AU - Liu, Yizhu

AU - Nielsen, Martin Meedom

AU - Robinson, Joseph S.

AU - Solomon, Edward I.

AU - Sokaras, Dimosthenis

AU - van Driel, Tim B.

AU - Weng, Tsu-Chien

AU - Zhu, Diling

AU - Persson, Petter

AU - Wärnmark, Kenneth

AU - Sundström, Villy

AU - Gaffney, Kelly J.

N1 - All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

PY - 2017

Y1 - 2017

N2 - 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=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-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 metal-centered 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, where N = 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.

AB - 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=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT) excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-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 metal-centered 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, where N = 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.

KW - Monte Carlo methods

KW - Emission spectra

KW - Absorption spectra

KW - Excited states

KW - Spin crossover

U2 - 10.1063/1.4985017

DO - 10.1063/1.4985017

M3 - Journal article

VL - 4

JO - Structural Dynamics

JF - Structural Dynamics

SN - 2329-7778

IS - 4

M1 - 044030

ER -