Deep red emitting heteroleptic Ir(III) complexes that incorporate unsymmetrical 4-quinoline carboxylic acid derived ligands
Deep red emitting heteroleptic Ir(III) complexes that incorporate unsymmetrical 4-quinoline carboxylic acid derived ligands
Six disubstituted ligands based upon 2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids have been synthesised, solvent-free, in one step from a range of commercially available isatin derivatives. These species behave as ancillary chelating ligands for Ir(III) complexes of the form [Ir(C^N)2(N^N)]PF6 (where C^N=cyclometalating ligand; N^N=2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids). An X-ray crystallographic study on one complex shows a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed for the cyclometalating ligands. DFT calculations predicted that variations in N^N ligand from 2,2′-bipyridine to L1–6 should localise the LUMO on to the Ln ligand and that the complexes are predicted to display MLCT/LLCT character. All complexes displayed luminescence in the deep red part of the visible region (674–679 nm) and emit from triplet states, but with little apparent tuning as a function of L1–6. Further time-resolved transient absorption spectroscopy supports the participation of these triplet states to the excited state character.
4-quinolinecarboxylic acid, cyclometalation, iridium, luminescence, synthesis
Elgar, Christopher E.
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Otaif, Haleema Y.
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Beames, Joseph M.
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Horton, Peter N.
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Coles, Simon J.
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Hallett, Andrew J.
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O'Kell, Sean P.
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Pope, Simon J.A.
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23 June 2023
Elgar, Christopher E.
f59426b7-72ba-4125-96e3-b9b63da790ff
Otaif, Haleema Y.
1b365536-1683-40d5-b6d2-3f869cdac579
Beames, Joseph M.
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Horton, Peter N.
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Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Hallett, Andrew J.
36cc4f6a-74d4-4894-8a65-8dd9d7803593
O'Kell, Sean P.
01ff0d06-c93a-455d-9586-c62b101eefc8
Pope, Simon J.A.
db9a489c-29ba-41cd-a96a-623bace0889d
Elgar, Christopher E., Otaif, Haleema Y., Beames, Joseph M., Horton, Peter N., Coles, Simon J., Hallett, Andrew J., O'Kell, Sean P. and Pope, Simon J.A.
(2023)
Deep red emitting heteroleptic Ir(III) complexes that incorporate unsymmetrical 4-quinoline carboxylic acid derived ligands.
European Journal of Inorganic Chemistry, 26 (18), [e202300102].
(doi:10.1002/ejic.202300102).
Abstract
Six disubstituted ligands based upon 2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids have been synthesised, solvent-free, in one step from a range of commercially available isatin derivatives. These species behave as ancillary chelating ligands for Ir(III) complexes of the form [Ir(C^N)2(N^N)]PF6 (where C^N=cyclometalating ligand; N^N=2-(2′-pyridinyl/pyrazinyl)quinoline-4-carboxylic acids). An X-ray crystallographic study on one complex shows a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed for the cyclometalating ligands. DFT calculations predicted that variations in N^N ligand from 2,2′-bipyridine to L1–6 should localise the LUMO on to the Ln ligand and that the complexes are predicted to display MLCT/LLCT character. All complexes displayed luminescence in the deep red part of the visible region (674–679 nm) and emit from triplet states, but with little apparent tuning as a function of L1–6. Further time-resolved transient absorption spectroscopy supports the participation of these triplet states to the excited state character.
Text
Eur J Inorg Chem - 2023 - Elgar - Deep Red Emitting Heteroleptic Ir III Complexes that Incorporate Unsymmetrical
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Accepted/In Press date: 28 March 2023
e-pub ahead of print date: 11 April 2023
Published date: 23 June 2023
Additional Information:
Funding Information:
Cardiff University (Knowledge Economy Skills Scholarships to C.E.E.) and STG Aerospace are thanked for financial support. We thank the EPSRC UK National Crystallographic Service at the University of Southampton and the Chemistry Department, Jazan University, Saudi Arabia, for financial support and a scholarship to H.Y.O.
Keywords:
4-quinolinecarboxylic acid, cyclometalation, iridium, luminescence, synthesis
Identifiers
Local EPrints ID: 477509
URI: http://eprints.soton.ac.uk/id/eprint/477509
ISSN: 1434-1948
PURE UUID: 34974e1c-52dd-44d7-ad5f-4267636c8667
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Date deposited: 07 Jun 2023 16:59
Last modified: 18 Mar 2024 02:51
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Contributors
Author:
Christopher E. Elgar
Author:
Haleema Y. Otaif
Author:
Joseph M. Beames
Author:
Peter N. Horton
Author:
Andrew J. Hallett
Author:
Sean P. O'Kell
Author:
Simon J.A. Pope
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