Tuning Tetramethoxy-acridiniums for Fluorophores and Organic Photoredox Catalysis

Marko H. Nowack; Magnus B. Johansen; Søren Sams; Andreas E. Hillers-Bendtsen; Kurt V. Mikkelsen; Bo W. Laursen

doi:10.1002/chem.202403451

Tuning Tetramethoxy-acridiniums for Fluorophores and Organic Photoredox Catalysis

Marko H. Nowack, Magnus B. Johansen, Søren Sams, Andreas E. Hillers-Bendtsen, Kurt V. Mikkelsen, Bo W. Laursen^*

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

Tetramethoxy substituted alkyl-acridiniums (TMAcr⁺) are readily available by facile nucleophilic aromatic substitution on tris(2,6-dimethoxyphenyl)carbenium, but are non-fluorescent, presumably due to intramolecular photoinduced electron transfer quenching. In this work we introduce electron withdrawing groups by electrophilic aromatic substitution reactions, leading to fluorescence turn-on. The acridiniums are moderately fluorescent (φ_f=20 %) with long fluorescene lifetimes (τ_f=9 ns). The positive excited state reduction potentials (E*_red=+1.6 V) make the TMAcr⁺ excellent electron acceptors in the excited state, and efficient reductive photoredox catalysts able to oxidize a broad range of substrates.

Original language	English
Journal	Chemistry - A European Journal
Volume	31
Issue number	4
ISSN	0947-6539
DOIs	https://doi.org/10.1002/chem.202403451
Publication status	Published - 2024

Bibliographical note

Funding Information:
This work was supported by the Novo Nordic Foundation (NNF20OC0062176). A.E.H.\u2010B., M.B.J., and K.V.M. acknowledge the Danish Council for Independent Research (DFF\u20100136\u201000081B and DFF\u201010.46540/3103\u201000261B) and the European Union's Horizon 2020 Framework Program (grant agreement number 951801) for financial support. The authors acknowledge Jesper D. Jensen for synthesizing the mono\u2010 and di\u2010chlorinated acridiniums.

Publisher Copyright:
© 2024 Wiley-VCH GmbH.

Keywords

Acridinium
Fluorescence
Organic chromophores
Photocatalysis
Photoinduced electron transfer

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Cite this

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title = "Tuning Tetramethoxy-acridiniums for Fluorophores and Organic Photoredox Catalysis",

abstract = "Tetramethoxy substituted alkyl-acridiniums (TMAcr+) are readily available by facile nucleophilic aromatic substitution on tris(2,6-dimethoxyphenyl)carbenium, but are non-fluorescent, presumably due to intramolecular photoinduced electron transfer quenching. In this work we introduce electron withdrawing groups by electrophilic aromatic substitution reactions, leading to fluorescence turn-on. The acridiniums are moderately fluorescent (φf=20 %) with long fluorescene lifetimes (τf=9 ns). The positive excited state reduction potentials (E*red=+1.6 V) make the TMAcr+ excellent electron acceptors in the excited state, and efficient reductive photoredox catalysts able to oxidize a broad range of substrates.",

keywords = "Acridinium, Fluorescence, Organic chromophores, Photocatalysis, Photoinduced electron transfer",

author = "Nowack, {Marko H.} and Johansen, {Magnus B.} and S{\o}ren Sams and Hillers-Bendtsen, {Andreas E.} and Mikkelsen, {Kurt V.} and Laursen, {Bo W.}",

note = "Funding Information: This work was supported by the Novo Nordic Foundation (NNF20OC0062176). A.E.H.\u2010B., M.B.J., and K.V.M. acknowledge the Danish Council for Independent Research (DFF\u20100136\u201000081B and DFF\u201010.46540/3103\u201000261B) and the European Union's Horizon 2020 Framework Program (grant agreement number 951801) for financial support. The authors acknowledge Jesper D. Jensen for synthesizing the mono\u2010 and di\u2010chlorinated acridiniums. Publisher Copyright: {\textcopyright} 2024 Wiley-VCH GmbH.",

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AU - Nowack, Marko H.

AU - Johansen, Magnus B.

AU - Sams, Søren

AU - Hillers-Bendtsen, Andreas E.

AU - Mikkelsen, Kurt V.

AU - Laursen, Bo W.

N1 - Funding Information: This work was supported by the Novo Nordic Foundation (NNF20OC0062176). A.E.H.\u2010B., M.B.J., and K.V.M. acknowledge the Danish Council for Independent Research (DFF\u20100136\u201000081B and DFF\u201010.46540/3103\u201000261B) and the European Union's Horizon 2020 Framework Program (grant agreement number 951801) for financial support. The authors acknowledge Jesper D. Jensen for synthesizing the mono\u2010 and di\u2010chlorinated acridiniums. Publisher Copyright: © 2024 Wiley-VCH GmbH.

PY - 2024

Y1 - 2024

N2 - Tetramethoxy substituted alkyl-acridiniums (TMAcr+) are readily available by facile nucleophilic aromatic substitution on tris(2,6-dimethoxyphenyl)carbenium, but are non-fluorescent, presumably due to intramolecular photoinduced electron transfer quenching. In this work we introduce electron withdrawing groups by electrophilic aromatic substitution reactions, leading to fluorescence turn-on. The acridiniums are moderately fluorescent (φf=20 %) with long fluorescene lifetimes (τf=9 ns). The positive excited state reduction potentials (E*red=+1.6 V) make the TMAcr+ excellent electron acceptors in the excited state, and efficient reductive photoredox catalysts able to oxidize a broad range of substrates.

AB - Tetramethoxy substituted alkyl-acridiniums (TMAcr+) are readily available by facile nucleophilic aromatic substitution on tris(2,6-dimethoxyphenyl)carbenium, but are non-fluorescent, presumably due to intramolecular photoinduced electron transfer quenching. In this work we introduce electron withdrawing groups by electrophilic aromatic substitution reactions, leading to fluorescence turn-on. The acridiniums are moderately fluorescent (φf=20 %) with long fluorescene lifetimes (τf=9 ns). The positive excited state reduction potentials (E*red=+1.6 V) make the TMAcr+ excellent electron acceptors in the excited state, and efficient reductive photoredox catalysts able to oxidize a broad range of substrates.

KW - Acridinium

KW - Fluorescence

KW - Organic chromophores

KW - Photocatalysis

KW - Photoinduced electron transfer

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VL - 31

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

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