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Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield

Turley, A.T.; Danos, A.; Prlj, A.; Monkman, A.P.; Curchod, B.F.E.; McGonigal, P.R.; Etherington, M.K.

Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield Thumbnail


Authors

A.T. Turley

A. Prlj

A.P. Monkman

B.F.E. Curchod

M.K. Etherington



Abstract

Charge transfer in organic fluorophores is a fundamental photophysical process that can be either beneficial, e.g., facilitating thermally activated delayed fluorescence, or detrimental, e.g., mediating emission quenching. N-Alkylation is shown to provide straightforward synthetic control of the charge transfer, emission energy and quantum yield of amine chromophores. We demonstrate this concept using quinine as a model. N-Alkylation causes changes in its emission that mirror those caused by changes in pH (i.e., protonation). Unlike protonation, however, alkylation of quinine’s two N sites is performed in a stepwise manner to give kinetically stable species. This kinetic stability allows us to isolate and characterize an N-alkylated analog of an ‘unnatural’ protonation state that is quaternized selectively at the less basic site, which is inaccessible using acid. These materials expose (i) the through-space charge-transfer excited state of quinine and (ii) the associated loss pathway, while (iii) developing a simple salt that outperforms quinine sulfate as a quantum yield standard. This N-alkylation approach can be applied broadly in the discovery of emissive materials by tuning charge-transfer states.

Citation

Turley, A., Danos, A., Prlj, A., Monkman, A., Curchod, B., McGonigal, P., & Etherington, M. (2020). Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield. Chemical Science, 11(27), 6990-6995. https://doi.org/10.1039/d0sc02460k

Journal Article Type Article
Acceptance Date Jun 8, 2020
Online Publication Date Jun 9, 2020
Publication Date Jul 21, 2020
Deposit Date Jun 9, 2020
Publicly Available Date Jun 9, 2020
Journal Chemical Science
Print ISSN 2041-6520
Electronic ISSN 2041-6539
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 11
Issue 27
Pages 6990-6995
DOI https://doi.org/10.1039/d0sc02460k
Related Public URLs https://chemrxiv.org/articles/Modulation_of_Charge_Transfer_by_N-Alkylation_to_Control_Photoluminescence_Energy_and_Quantum_Yield/12159114/1

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