Rational construction of ratiometric near-infrared fluorescent probe based on flavylium derivatives for detection and imaging of ClO- in plant-water and biological systems.

The residue of hypochlorite (ClO-) in aquatic environments poses a serious threat to plant growth, creating an urgent need for real-time and accurate monitoring methods. In this study, a series of flavylium-based fluorescent probes with different D-A-D structure were designed and synthesized, PB-OH was selected as candidate to specifically recognize ClO- by undergoing a cyclooxidation reaction due to its optimal performer. It exhibited a distinct ratio-type fluorescence and color change to ClO- with high selectivity, rapid response, and excellent sensitivity. A significant feature of PB-OH is its ability to detect ClO- visually, leveraging a smartphone as a handheld signal-processing tool. Furthermore, PB-OH was effectively applied for the dynamic detection of ClO- in simulated contaminated water and hydroponically cultured seedlings. Finally, PB-OH has also been successfully applied to cell imaging and zebrafish imaging and could be localized in mitochondria. This study not only developed an efficient analytical tool for detecting ClO- in biological systems but also offers key technical support for revealing the toxicity mechanism of ClO- on plants.