Turn‐on Fluorescent Probes Based on Aggregation Enhanced Emission Characteristics for Hydroxyl Radical With Naked‐Eye Recognition

ABSTRACT Hydroxyl radicals (•OH), possessing extremely strong oxidative capability, play crucial roles in various fields. The detection of •OH is quite important but remains challenging. In this work, a series of quinoline‐based fluorescent probes (F‐1, F‐2, F‐3, and F‐4) with aggregation enhanced emission (AEE) characteristics were designed and synthesized. All four probes exhibited pronounced turn‐on fluorescence responses toward •OH with high selectivity and specificity, accompanied by distinct naked‐eye recognition manifested as bright cyan fluorescence. Among them, probe F‐4 showed the best sensing performance: upon the addition of 100 µM •OH, its fluorescence intensity increased by 4.77‐fold, and the limit of detection was as low as 124 nM within a linear detection range of 10 to 100 µM. The mechanism of fluorescence enhancement may be attributed to the oxidation of the –CH 2 OH group in the probes by •OH to form –CH 2 CHO. Furthermore, a paper‐based sensor was fabricated by simply depositing F‐4 onto filter paper, enabling rapid naked‐eye detection of •OH. This work provides a promising strategy for the development of novel AEE active fluorescent probes for •OH detection.