A Chromene-Based Fluorescent Probe for Rapid Hypochlorite Detection in Environmental Matrices, Plant Tissues, and a Smartphone Platform

Abstract Hypochlorite (ClO − ) plays important roles in maintaining physiological homeostasis. However, elevated level of ClO − poses significant risks to both human health and the environment, and rapid on-site detection remains challenging. In this work, a known chromene-based fluorescent probe (1), originally recognizing nitric oxide in DMSO-PBS buffer, was found to respond selectively to ClO − when tested in an ethanol-water (1:1, v/v) medium. Under these conditions, the probe exhibited a rapid turn-on fluorescence response at 530 nm within 30 seconds upon exposure to ClO⁻. Probe 1 showed properties in detecting ClO − with high sensitivity (limit of detection 11 nM), excellent selectivity over other analytes, good stability across pH 4–10, and a broad linear range (0–170 µM). Mechanistic studies confirmed that ClO − triggers oxidative cleavage of the imine bond, regenerating the strongly fluorescent aldehyde 1A . Based on this response, we developed a smartphone-based portable platform for accurate ClO − quantification in real water samples with recoveries of 97.4–104.2%. The probe was further validated for ClO − detection in diverse applications, including soil samples, living plant seedings, microfluidic devices, and real-time monitoring in plant cells. This work provides a rapid and portable tool for ClO − monitoring across environmental and biological matrices, effectively expanding the functionality of a single molecular platform.