Organometallic platinum(II) photosensitisers that demonstrate ligand-modulated triplet-triplet annihilation energy upconversion efficiencies
Organometallic platinum(II) photosensitisers that demonstrate ligand-modulated triplet-triplet annihilation energy upconversion efficiencies
A series of 2-phenylquinoxaline ligands have been synthesised that introduce either CF3 or OCF3 electron-withdrawing groups at different positions of the phenyl ring. These ligands were investigated as cyclometalating reagents for platinum(II) to give neutral complexes of the form [Pt(C^N)(acac)] (in which C^N=cyclometalating ligand; acac=acetyl acetonate). X-ray crystallographic studies on three examples showed that the complexes adopt an approximate square planar geometry. All examples revealed strong Pt−Pt linear contacts of 3.2041(6), 3.2199(3) and 3.2586(2) Å. The highly coloured complexes display efficient visible absorption at 400–500 nm (ϵ ≈5000 M−1 cm−1) and orange red photoluminescent characteristics (λem=603–620 nm; Φem ≤37 %), which were subtly tuned by the ligand. Triplet emitting character was confirmed by microsecond luminescence lifetimes and the photogeneration of singlet oxygen with quantum efficiencies up to 57 %. Each complex was investigated as a photosensitiser for triplet–triplet annihilation energy upconversion using 9,10-diphenylanthracene as the annihilator species: a range of good upconversion efficiencies (ΦUC 5.9–14.1 %) were observed and shown to be strongly influenced by the ligand structure in each case.
DFT calculations, platinum complexes, quinoxalines, spectroscopy, upconversion
Fitzgerald, Sophie A.
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Xiao, Xiao
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Zhao, Jianzhang
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Horton, Peter N.
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Coles, Simon J.
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Knighton, Richard C.
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Ward, Benjamin D.
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Pope, Simon J.A.
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10 February 2023
Fitzgerald, Sophie A.
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Xiao, Xiao
181c5664-2215-4249-92a5-a2fc4d36e784
Zhao, Jianzhang
08415724-251c-475a-97d7-bb21408eb959
Horton, Peter N.
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Coles, Simon J.
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Knighton, Richard C.
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Ward, Benjamin D.
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Pope, Simon J.A.
db9a489c-29ba-41cd-a96a-623bace0889d
Fitzgerald, Sophie A., Xiao, Xiao, Zhao, Jianzhang, Horton, Peter N., Coles, Simon J., Knighton, Richard C., Ward, Benjamin D. and Pope, Simon J.A.
(2023)
Organometallic platinum(II) photosensitisers that demonstrate ligand-modulated triplet-triplet annihilation energy upconversion efficiencies.
Chemistry - A European Journal, 29 (9), [e202203241].
(doi:10.1002/chem.202203241).
Abstract
A series of 2-phenylquinoxaline ligands have been synthesised that introduce either CF3 or OCF3 electron-withdrawing groups at different positions of the phenyl ring. These ligands were investigated as cyclometalating reagents for platinum(II) to give neutral complexes of the form [Pt(C^N)(acac)] (in which C^N=cyclometalating ligand; acac=acetyl acetonate). X-ray crystallographic studies on three examples showed that the complexes adopt an approximate square planar geometry. All examples revealed strong Pt−Pt linear contacts of 3.2041(6), 3.2199(3) and 3.2586(2) Å. The highly coloured complexes display efficient visible absorption at 400–500 nm (ϵ ≈5000 M−1 cm−1) and orange red photoluminescent characteristics (λem=603–620 nm; Φem ≤37 %), which were subtly tuned by the ligand. Triplet emitting character was confirmed by microsecond luminescence lifetimes and the photogeneration of singlet oxygen with quantum efficiencies up to 57 %. Each complex was investigated as a photosensitiser for triplet–triplet annihilation energy upconversion using 9,10-diphenylanthracene as the annihilator species: a range of good upconversion efficiencies (ΦUC 5.9–14.1 %) were observed and shown to be strongly influenced by the ligand structure in each case.
Text
Chemistry A European J - 2022 - Fitzgerald - Organometallic Platinum II Photosensitisers that Demonstrate Ligand‐Modulated
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Accepted/In Press date: 17 November 2022
e-pub ahead of print date: 17 November 2022
Published date: 10 February 2023
Additional Information:
Funding Information:
Cardiff University (Knowledge Economy Skills Scholarship to SAF) and STG Aerospace (Dr Andrew Hallett and Dr Sean O'Kell) are thanked for financial support. The Leverhulme Trust is also thanked for funding (RPG-2021-003). We thank the staff of the Engineering and Physical Sciences Research Council (EPSRC) UK National Crystallographic Service at the University of Southampton.
Funding Information:
Cardiff University (Knowledge Economy Skills Scholarship to SAF) and STG Aerospace (Dr Andrew Hallett and Dr Sean O'Kell) are thanked for financial support. The Leverhulme Trust is also thanked for funding (RPG‐2021‐003). We thank the staff of the Engineering and Physical Sciences Research Council (EPSRC) UK National Crystallographic Service at the University of Southampton.
Publisher Copyright:
© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.
Keywords:
DFT calculations, platinum complexes, quinoxalines, spectroscopy, upconversion
Identifiers
Local EPrints ID: 475521
URI: http://eprints.soton.ac.uk/id/eprint/475521
ISSN: 0947-6539
PURE UUID: a928426b-268e-44b2-ae9e-7dca6f9e4f88
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Date deposited: 21 Mar 2023 17:35
Last modified: 18 Mar 2024 04:15
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Contributors
Author:
Sophie A. Fitzgerald
Author:
Xiao Xiao
Author:
Jianzhang Zhao
Author:
Peter N. Horton
Author:
Richard C. Knighton
Author:
Simon J.A. Pope
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