Highly Efficient and Reversible Nitric Oxide Capture by Functionalized Ionic Liquids through Multiple-Site Absorption

Abstract

A series of basicity-tunable ionic liquids with carboxylate and sulfonate anion were designed, prepared, and applied in NO capture. Both high absorption capacity and low desorption residue were achieved through tuning the basicity of the anion, leading to a superhigh working capacity of more than 6 mol per mol ionic liquid, which is superior to that of traditional absorbents. Through a combination of absorption experiments, quantum chemical calculations, and spectroscopic investigations, the results indicated that such a high absorption capacity was originated from multiple sites interaction between oxygen atoms of carboxylate or sulfonate anion and NO, while the reduced interaction induced by the decreased basicity of the O-site ionic liquid led to excellent desorption. We show that the highly efficient and reversible NO capture by these tunable ionic liquids provides a new strategy for improving gas capture and utilization, which is also important for some other fields such as material, biology, and medicine.