Dr Ross Davidson ross.davidson@durham.ac.uk
Academic Visitor
Tuning Emission Lifetimes of Ir(C^N)2(acac) Complexes with Oligo(phenyleneethynylene) Groups
Davidson, Ross; Hsu, Yu-Ting; Fox, Mark A.; Aguilar, Juan A.; Yufit, Dmitry; Beeby, Andrew
Authors
Yu-Ting Hsu
Dr Mark Fox m.a.fox@durham.ac.uk
Assistant Professor
Dr Juan Aguilar Malavia j.a.aguilar@durham.ac.uk
Solution NMR Service Senior Manager
Dr Dmitry Yufit d.s.yufit@durham.ac.uk
Academic Visitor
Professor Andrew Beeby andrew.beeby@durham.ac.uk
Professor
Abstract
Emissive compounds with long emission lifetimes (μs to ms) in the visible region are of interest for a range of applications, from oxygen sensing to cellular imaging. The emission behavior of Ir(ppy)2(acac) complexes (where ppy is the 2-phenylpyridyl chelate and acac is the acetylacetonate chelate) with an oligo(para-phenyleneethynylene) (OPE3) motif containing three para-rings and two ethynyl bridges attached to acac or ppy is examined here due to the accessibility of the long-lived OPE3 triplet states. Nine Ir(ppy)2(acac) complexes with OPE3 units are synthesized where the OPE3 motif is at the acac moiety (aOPE3), incorporated in the ppy chelate (pOPE3) or attached to ppy via a durylene link (dOPE3). The aOPE3 and dOPE3 complexes contain OPE3 units that are decoupled from the Ir(ppy)2(acac) core by adopting perpendicular ring–ring orientations, whereas the pOPE3 complexes have OPE3 integrated into the ppy ligand to maximize electronic coupling with the Ir(ppy)2(acac) core. While the conjugated pOPE3 complexes show emission lifetimes of 0.69–32.8 μs similar to the lifetimes of 1.00–23.1 μs for the non-OPE3 Ir(ppy)2(acac) complexes synthesized here, the decoupled aOPE3 and dOPE3 complexes reveal long emission lifetimes of 50–625 μs. The long lifetimes found in aOPE3 and dOPE3 complexes are due to intramolecular reversible electronic energy transfer (REET) where the long-lived triplet-state metal to ligand charge transfer (3MLCT) states exchange via REET with the even longer-lived triplet-state localized OPE3 states. The proposed REET process is supported by changes observed in excitation wavelength-dependent and time-dependent emission spectra from aOPE3 and dOPE3 complexes, whereas emission spectra from pOPE3 complexes remain independent of the excitation wavelength and time due to the well-established 3MLCT states of many Ir(ppy)2(acac) complexes. The long lifetimes, visible emission maxima (524–526 nm), and photoluminescent quantum yields of 0.44–0.60 for the dOPE3 complexes indicate the possibility of utilizing such compounds in oxygen-sensing and cellular imaging applications.
Citation
Davidson, R., Hsu, Y., Fox, M. A., Aguilar, J. A., Yufit, D., & Beeby, A. (2023). Tuning Emission Lifetimes of Ir(C^N)2(acac) Complexes with Oligo(phenyleneethynylene) Groups. Inorganic Chemistry, 62(6), 2793-2805. https://doi.org/10.1021/acs.inorgchem.2c03934
Journal Article Type | Article |
---|---|
Online Publication Date | Jan 27, 2023 |
Publication Date | Feb 13, 2023 |
Deposit Date | Feb 8, 2023 |
Publicly Available Date | Mar 31, 2023 |
Journal | Inorganic Chemistry |
Print ISSN | 0020-1669 |
Electronic ISSN | 1520-510X |
Publisher | American Chemical Society |
Peer Reviewed | Peer Reviewed |
Volume | 62 |
Issue | 6 |
Pages | 2793-2805 |
DOI | https://doi.org/10.1021/acs.inorgchem.2c03934 |
Public URL | https://durham-repository.worktribe.com/output/1181285 |
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Copyright Statement
© 2023 The Authors. Published by American Chemical Society. This work is licensed under the Creative Commons Attribution 4.0 International License.
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