Dual-channel sensing of CO₂: Reversible solution-gel transition and gelation-induced fluorescence enhancement

It is imperative for various applications to develop new sensing systems in the visualization and detection of CO₂. Here, several aroylhydrazone-derivatized organogelators have been prepared and developed as CO₂ sensors via the anion-activated strategy. These new compounds can gel some of polar and apolar organic solvents to form stable organogels which have been well characterized by field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy, concentration- and temperature-dependent ¹H NMR spectra, PXRD, and UV–vis spectroscopy. In addition, they can show gelation-induced fluorescence enhancement performances which have been proven to derive from the aggregation-induced emission (AIE) effect. In particular, the fluoride anion-triggered solutions of the organogelators can permit naked-eye sensing of CO₂ in air via the solution-to-gel transition. Besides, the developed gelation systems can also be used to provide quantitative means for CO₂ stream through re-gelation induced fluorescence enhancement. Moreover, the reversibility of these sensing systems for the capture and release of CO₂ enhances their applicable potential.