Issue 19, 2024

Experimental and theoretical comprehension of ESIPT fluorophores based on a 2-(2′-hydroxyphenyl)-3,3′-dimethylindole (HDMI) scaffold

Abstract

Excited-State Intramolecular Proton Transfer (ESIPT) emission is associated with intense single or multiple fluorescence in the solid-state, along with enhanced photostability and sensitivity to the close environment. As a result, ESIPT probes are attractive candidates for ratiometric sensing of a variety of substrates. A new family of ESIPT fluorophores is described herein, inspired by the well-known 2-(2'hydroxyphenyl)benzazole (HBX) organic scaffold. The connection of 3,3′-dimethylindole (or 3H-indole) derivatives with phenol rings triggers the formation of novel 2-(2′-hydroxyphenyl)-3,3′-dimethylindole (HDMI) fluorophores, capable of stimuli-responsive ESIPT emission. This brand new family of dyes displays redshifted emission, as compared to HBX, along with an unprecedented acid/base-mediated stabilization of different rotamers, owing to supramolecular interactions with methyl groups. These compounds are therefore highly sensitive to external stimuli, such as the presence of acid or base, where protonated and deprotonated species have specific optical signatures. Moreover, a new pyridine-functionalized HDMI dye displays acid-sensitive AIE properties. The photophysical properties of all compounds have also been studied using ab initio calculations to support experiments in deciphering the nature of the various radiative transitions observed and the related excited rotameric species.

Graphical abstract: Experimental and theoretical comprehension of ESIPT fluorophores based on a 2-(2′-hydroxyphenyl)-3,3′-dimethylindole (HDMI) scaffold

Supplementary files

Article information

Article type
Edge Article
Submitted
22 Mar 2024
Accepted
16 Apr 2024
First published
16 Apr 2024
This article is Open Access

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

Chem. Sci., 2024,15, 7206-7218

Experimental and theoretical comprehension of ESIPT fluorophores based on a 2-(2′-hydroxyphenyl)-3,3′-dimethylindole (HDMI) scaffold

T. Stoerkler, G. Ulrich, P. Retailleau, A. D. Laurent, D. Jacquemin and J. Massue, Chem. Sci., 2024, 15, 7206 DOI: 10.1039/D4SC01937G

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