Anion-Functionalized Pillararenes for Efficient Sulfur Dioxide Capture: Significant Effect of the Anion and the...

A series of anion-functionalized pillararenes were prepared and applied in the capture of SO₂ through incorporating an anion with different basicity into pillararenes. A high SO₂ absorption capacity up to 15.9 mmol g^-1 and excellent reversibility were achieved by tuning the basicity of the anion and the size of the cavity. Spectroscopic investigations and DFT calculations indicated that high SO₂ capacity originated from multiple sites interaction between SO₂ and the anion, where SO₂ chemical absorption was significant strengthened by the cavity, because the anion was confined in the window of the cavity and the window was electron-deficient. Interestingly, a phase transition occurred during absorption and desorption process. The method proposed in this work provided an efficient strategy for improving gas absorption through a simple functionalization of the supermolecule, which was also very important for some other fields such as polymers and materials.