Designing an anion-functionalized fluorescent ionic liquid as an efficient and reversible turn-off sensor for detecting SO2

Abstract

A novel anion-functionalized fluorescent ionic liquid was designed and prepared, which was capable of capturing sulphur dioxide with high capacity and could also be used as a good colorimetric and fluorescent SO₂ sensor. Compared to conventional fluorescent sensors, this fluorescent ionic liquid did not undergo aggregation-caused quenching or aggregation-induced emission, and the fluorescence was quenched when exposed to SO₂, and the fluorescence would quench when exposed to SO₂. The experimental absorption, spectroscopic investigation, and quantum chemical calculations indicated that the quenching of the fluorescence originated from SO₂ physical absorption, not chemical absorption. Furthermore, this fluorescent ionic liquid exhibited high selectivity, good quantification, and excellent reversibility for SO₂ detection, and showed potential for an excellent liquid sensor.