Advancements in ESIPT probe research over the past three years based on different fluorophores

Proton transfer plays a crucial role in physical, chemical, and biological macromolecular systems, and the Excited-State Intramolecular Proton Transfer (ESIPT) effect is widely studied in the field of fluorescent materials. Fluorophores exhibiting the ESIPT effect, such as 2- (2′-hydroxyphenyl) benzothiazole (HBT) and salicylaldehyde, possess significant advantages over other types of fluorophores, including a large Stokes shift, long fluorescence lifetime, high fluorescence quantum yield, and ease of synthesis. Additionally, the dual-channel fluorescence emission of ESIPT fluorophores provides more opportunities for the development of “turn-on,” “turn-off,” and “ratio-type” fluorescence probes. Over the past three years (2020–2023), the number of publications on ESIPT fluorescent probes has steadily increased, indicating continued research value in this field. However, there have been few comprehensive reviews in this area, and the ESIPT effect is influenced by factors such as hydrogen bonding, microenvironment, and substituents, posing challenges to the development of efficient fluorescent probes. Therefore, herein, we systematically summarize ESIPT probes with excellent fluorescence properties and outstanding recognition abilities over the past three years, based on different ESIPT fluorophores. Subsequently, we provide an overview of prevalent recognition mechanisms employed by ESIPT fluorescence probes, including ion chelation, modification of active protons, modulation of electron cloud density, specificity achieved through enzymatic interactions, etc. Finally, a summary and prospects for future research are provided.