A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence

Pavel Chabera, Yizhu Liu, Om Prakash, Erling Thyrhaug, Amal El Nahhas, Alireza Honarfar, Sofia Essen, Lisa A. Fredin, Tobias C. B. Harlang, Kasper Skov Kjær, Karsten Handrup, Fredric Ericson, Hideyuki Tatsuno, Kelsey Morgan, Joachim Schnadt, Lennart Haggstrom, Tore Ericsson, Adam Sobkowiak, Sven Lidin, Ping Huang & 7 others Stenbjorn Styring, Jens Uhlig, Jesper Bendix, Reiner Lomoth, Villy Sundstrom, Petter Persson, Kenneth Warnmark

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes of ruthenium(5) and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron(6) and copper(7) being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs(6,8-10), it remains a formidable scientific challenge(11) to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered(12) photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers(13-15). Here we present the iron complex [Fe(btz)(3)](3+) (where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)), and show that the superior sigma-donor and pi-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d(5) complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state that is rarely seen for transition-metal complexes(4,16,17). The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.
Original languageEnglish
JournalNature
Volume543
Issue number7647
Number of pages19
ISSN0028-0836
DOIs
Publication statusPublished - 2017

Cite this

Chabera, P., Liu, Y., Prakash, O., Thyrhaug, E., El Nahhas, A., Honarfar, A., ... Warnmark, K. (2017). A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence. Nature, 543(7647). https://doi.org/10.1038/nature21430
Chabera, Pavel ; Liu, Yizhu ; Prakash, Om ; Thyrhaug, Erling ; El Nahhas, Amal ; Honarfar, Alireza ; Essen, Sofia ; Fredin, Lisa A. ; Harlang, Tobias C. B. ; Kjær, Kasper Skov ; Handrup, Karsten ; Ericson, Fredric ; Tatsuno, Hideyuki ; Morgan, Kelsey ; Schnadt, Joachim ; Haggstrom, Lennart ; Ericsson, Tore ; Sobkowiak, Adam ; Lidin, Sven ; Huang, Ping ; Styring, Stenbjorn ; Uhlig, Jens ; Bendix, Jesper ; Lomoth, Reiner ; Sundstrom, Villy ; Persson, Petter ; Warnmark, Kenneth. / A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence. In: Nature. 2017 ; Vol. 543, No. 7647.
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title = "A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence",
abstract = "Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes of ruthenium(5) and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron(6) and copper(7) being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs(6,8-10), it remains a formidable scientific challenge(11) to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered(12) photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers(13-15). Here we present the iron complex [Fe(btz)(3)](3+) (where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)), and show that the superior sigma-donor and pi-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d(5) complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state that is rarely seen for transition-metal complexes(4,16,17). The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.",
author = "Pavel Chabera and Yizhu Liu and Om Prakash and Erling Thyrhaug and {El Nahhas}, Amal and Alireza Honarfar and Sofia Essen and Fredin, {Lisa A.} and Harlang, {Tobias C. B.} and Kj{\ae}r, {Kasper Skov} and Karsten Handrup and Fredric Ericson and Hideyuki Tatsuno and Kelsey Morgan and Joachim Schnadt and Lennart Haggstrom and Tore Ericsson and Adam Sobkowiak and Sven Lidin and Ping Huang and Stenbjorn Styring and Jens Uhlig and Jesper Bendix and Reiner Lomoth and Villy Sundstrom and Petter Persson and Kenneth Warnmark",
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volume = "543",
journal = "Nature",
issn = "0028-0836",
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number = "7647",

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Chabera, P, Liu, Y, Prakash, O, Thyrhaug, E, El Nahhas, A, Honarfar, A, Essen, S, Fredin, LA, Harlang, TCB, Kjær, KS, Handrup, K, Ericson, F, Tatsuno, H, Morgan, K, Schnadt, J, Haggstrom, L, Ericsson, T, Sobkowiak, A, Lidin, S, Huang, P, Styring, S, Uhlig, J, Bendix, J, Lomoth, R, Sundstrom, V, Persson, P & Warnmark, K 2017, 'A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence', Nature, vol. 543, no. 7647. https://doi.org/10.1038/nature21430

A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence. / Chabera, Pavel; Liu, Yizhu; Prakash, Om; Thyrhaug, Erling; El Nahhas, Amal; Honarfar, Alireza; Essen, Sofia; Fredin, Lisa A.; Harlang, Tobias C. B.; Kjær, Kasper Skov; Handrup, Karsten; Ericson, Fredric; Tatsuno, Hideyuki; Morgan, Kelsey; Schnadt, Joachim; Haggstrom, Lennart; Ericsson, Tore; Sobkowiak, Adam; Lidin, Sven; Huang, Ping; Styring, Stenbjorn; Uhlig, Jens; Bendix, Jesper; Lomoth, Reiner; Sundstrom, Villy; Persson, Petter; Warnmark, Kenneth.

In: Nature, Vol. 543, No. 7647, 2017.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence

AU - Chabera, Pavel

AU - Liu, Yizhu

AU - Prakash, Om

AU - Thyrhaug, Erling

AU - El Nahhas, Amal

AU - Honarfar, Alireza

AU - Essen, Sofia

AU - Fredin, Lisa A.

AU - Harlang, Tobias C. B.

AU - Kjær, Kasper Skov

AU - Handrup, Karsten

AU - Ericson, Fredric

AU - Tatsuno, Hideyuki

AU - Morgan, Kelsey

AU - Schnadt, Joachim

AU - Haggstrom, Lennart

AU - Ericsson, Tore

AU - Sobkowiak, Adam

AU - Lidin, Sven

AU - Huang, Ping

AU - Styring, Stenbjorn

AU - Uhlig, Jens

AU - Bendix, Jesper

AU - Lomoth, Reiner

AU - Sundstrom, Villy

AU - Persson, Petter

AU - Warnmark, Kenneth

PY - 2017

Y1 - 2017

N2 - Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes of ruthenium(5) and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron(6) and copper(7) being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs(6,8-10), it remains a formidable scientific challenge(11) to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered(12) photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers(13-15). Here we present the iron complex [Fe(btz)(3)](3+) (where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)), and show that the superior sigma-donor and pi-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d(5) complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state that is rarely seen for transition-metal complexes(4,16,17). The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

AB - Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes of ruthenium(5) and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron(6) and copper(7) being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs(6,8-10), it remains a formidable scientific challenge(11) to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered(12) photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers(13-15). Here we present the iron complex [Fe(btz)(3)](3+) (where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)), and show that the superior sigma-donor and pi-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d(5) complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state that is rarely seen for transition-metal complexes(4,16,17). The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

U2 - 10.1038/nature21430

DO - 10.1038/nature21430

M3 - Journal article

VL - 543

JO - Nature

JF - Nature

SN - 0028-0836

IS - 7647

ER -

Chabera P, Liu Y, Prakash O, Thyrhaug E, El Nahhas A, Honarfar A et al. A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence. Nature. 2017;543(7647). https://doi.org/10.1038/nature21430