Fluorescence Probes Based on Aminoboranes for the Detection of Fluoride Ions and Nitroaromatics: A Bifunctional Fluorescence Detection Platform

ABSTRACT Small‐molecule‐based fluorescent probes have garnered significant attention because of their excellent optical properties. Among these, multi‐stimuli‐responsive molecular fluorescent probes have been rapidly developed for their wide range of applications. In this study, we designed a bifunctional fluorescent probe based on three‐coordinate boron compounds to detect fluoride ions and 4‐nitrophenol. Two compounds NB1 and NB2 , containing B‐mesityl 2 acceptors (A) and nitrogen‐containing aromatic donors (D), were confirmed via single‐crystal X‐ray diffraction. The donor–acceptor (D–A) structure and substantial steric hindrance enable these compounds to exhibit efficient fluorescence emission in both liquid and solid states. Leveraging the properties of three‐coordinate boron, these two compounds exhibit a visible and rapid response to fluoride ions, with detection limits of 0.41 μM for NB1 and 1.31 μM for NB2 . The detection mechanism was corroborated by 19 F NMR and fluorescence emission spectra. Moreover, owing to the D–A B–N unit, both compounds exhibit a significant and rapid response to 4‐nitrophenol, resulting from interrupted charge transfer. These compounds serve as fluorescent probes with outstanding bifunctionality, stability, and high efficiency. Given the growing demand for multi‐stimuli‐responsive fluorescent probes, NB1 and NB2 possess great potential for a wide range of future sensing and detection applications.