Issue 45, 2022

Controlling the fluorescence quantum yields of benzothiazole-difluoroborates by optimal substitution

Abstract

Precise tuning of the fluorescence quantum yield, vital for countless applications of fluorophores, remains exceptionally challenging due to numerous factors affecting energy dissipation phenomena often leading to its counterintuitive behavior. In contrast to the absorption and emission wavelength which can be precisely shifted to the desired range by simple structural changes, no general strategy exists for controllable modification of the fluorescence quantum yield. The rigidification of the molecular skeleton is known to usually enhance the emission and can be practically realized via the limiting molecular vibrations by aggregation. However, the subtle balance between the abundant possible radiative and non-radiative decay pathways makes the final picture exceptionally sophisticated. In the present study, a series of nine fluorophores obtained by peripheral substitution with two relatively mild electron donating and electron withdrawing groups are reported. The obtained fluorescence quantum yields range from dark to ultra-bright and the extreme values are obtained for the isomeric molecules. These severe changes in emission efficiency have been shown to arise from the complex relationship between the Franck–Condon excited state and conical intersection position. The experimental findings are rationalized by the advanced quantum chemical calculations delivering good correlation between the measured emission parameters and theoretical radiative and internal conversion rate constants. Therefore, the described substituent exchange provides a method to rigorously adjust the properties of molecular probes structurally similar to thioflavin T.

Graphical abstract: Controlling the fluorescence quantum yields of benzothiazole-difluoroborates by optimal substitution

Supplementary files

Article information

Article type
Edge Article
Submitted
09 Sep 2022
Accepted
21 Oct 2022
First published
24 Oct 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2022,13, 13347-13360

Controlling the fluorescence quantum yields of benzothiazole-difluoroborates by optimal substitution

P. Rybczyński, M. H. E. Bousquet, A. Kaczmarek-Kędziera, B. Jędrzejewska, D. Jacquemin and B. Ośmiałowski, Chem. Sci., 2022, 13, 13347 DOI: 10.1039/D2SC05044G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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