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 SO 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 SO, and the fluorescence would quench when exposed to SO. The experimental absorption, spectroscopic investigation, and quantum chemical calculations indicated that the quenching of the fluorescence originated from SO physical absorption, not chemical absorption. Furthermore, this fluorescent ionic liquid exhibited high selectivity, good quantification, and excellent reversibility for SO detection, and showed potential for an excellent liquid sensor.

Molecular understanding of a π-conjugated polymer/solid-state ionic liquid complex as a highly sensitive and selective gas sensor

“…11 Ionic liquids are desirable inclusions for gas sensing applications due to their good gas solubility, tunable physiochemical properties, and air and water stability. 12,13 The disparity in the surface energy and hydrophobicity of conjugated polymers and liquid state ionic liquids can cause difficulties in realising efficient devices; instead, they often have slow turn-on and require prebiasing. 14 Recently, the development of a solid-state ionic liquid (SSIL) with matching surface energy and stable ion diffusion has been shown to significantly improve device performance.…”

The role of cations in the interactions between anionic N-heterocycles and SO2

“…The Gaussian 09 package 33 was chosen to conduct all the calculations. Geometry optimizations were carried out unrestrained at the model chemistry of B3LYP 34 /6–311 ++ G(d, p) 35 (SDD 36 for the third to fifth period elements), which has shown appreciable performance over a wide range of NHCs 5 , 7 , 8 , 10 , 12 , 24 , 28 . Frequency analyses with the same model chemistry followed the structure optimization to identify energy minimum.…”

“…Actually, SO 2 rarely breaks the ion pair 8 , 15 , 23 – 27 . Still for simplicity, calculations of SO 2 interacting with ILs were routinely carried out in the absence of cation since the cation effects are assumed to be negligible 5 , 7 , 9 , 10 , 12 , 28 . To date, whether cation promotes or restrains the binding between NHC and SO 2 has not yet been clarified.…”

Affinity Ionic Liquids for Chemoselective Gas Sensing

“…Statistical analysis further showed that IL-based array can be promising through providing unique response patterns for each vapor [ 105 ]. In addition, further modification of ILs and incorporation with other materials (e.g., ethyl cellulose matrix, electrospun nanofiber, or carbon nanotubes) have led to successful sensing of CO 2 and SO 2 [ 106 , 107 , 108 , 109 ].…”