Achieving Sub‐ppm Sensitivity in SO₂ Detection with a Chemically Stable Covalent Organic Framework

We report the inaugural experimental investigation of covalent organic frameworks (COFs) to address the formidable challenge of SO 2 detection. Specifically, an imine‐functionalized COF (SonoCOF‐9) demonstrated a modest and reversible SO 2 sorption of 3.5 mmol g −1 at 1 bar and 298 K. At 0.1 bar (and 298 K), the total SO 2 uptake reached 0.91 mmol g −1 with excellent reversibility for at least 50 adsorption‐desorption cycles. An isosteric enthalpy of adsorption (Δ H ads ) for SO 2 equaled −42.3 kJ mol −1 , indicating a relatively strong interaction of SO 2 molecules with the COF material. Also, molecular dynamics simulations and Møller–Plesset perturbation theory calculations showed the interaction of SO 2 with π density of the rings and lone pairs of the N atoms of SonoCOF‐9. The combination of experimental data and theoretical calculations corroborated the potential use of this COF for the selective detection and sensing of SO 2 at the sub‐ppm level (0.0064 ppm of SO 2 ).