Fluorescent Ionic Liquid Membranes Based on Coumarin for the Real-Time and Visual Detection of Gaseous SO2

Presented here is a novel design strategy that utilizes anion-functionalized ionic liquids (ILs) to achieve visual and real-time detection of gaseous SO 2 . A coumarin fluorophore was innovatively covalently linked onto an IL and exhibited fluorescent signal response for SO 2 due to strong chemical interactions. The sensor consisting of this IL displayed high sensitivity and selectivity, even toward trace amounts of SO 2 (<0.2 ppm). Furthermore, this sensor overcame weak anti-interference ability and water-sensitivity issues. Benefiting from its excellent solubility, the sensor could be assembled into a simple and portable membrane device and exhibited excellent reusability (>12 times). The reported membrane sensor may be used as a next-generation gas sensor with superior SO 2 -response performance, enabling a wide application for monitoring harmful gases.