Tailoring the Gating Effect of Organic Cage via a Porous Liquid Approach

Abstract Porous liquids (PLs) represent a new frontier in material design combining the merits of solid porous host and liquid phase in gas separation and catalysis. Herein, the PL construction approach is harnessed to tailor the gating effect of organic cages toward enhanced gas separation. A type‐II fluorinated PL (F‐PL) is developed via liquifying a fluorinated organic cage (F‐cage) by a fluorinated ionic liquid (F‐IL). The F‐cage is featured by a small window size (≈5.1 Å), high surface area, good stability under highly ionic conditions, and abundant fluorine moieties. The F‐IL possesses high steric hindrance (bulky cation) and structure similarity with the F‐cage (fluorinated alkyl chain in the anion). The existing status structure integrity of F‐cage in F‐IL upon F‐PL formation is illustrated via spectroscopy and X‐ray‐based techniques. The existence of rigid voids in F‐PL is illustrated by positron annihilation lifetime spectroscopy (PALS) and the improved gas uptake capacity than F‐IL via pressure‐swing CO 2 uptake isotherms (0−40) bar. The comparison of the gas uptake behavior (CO 2 , N 2 , CH 4 , and Xe) of F‐PL and F‐cage, combining the computational simulation, highlights that the PL construction can be leveraged to tune the window size of porous scaffolds, leading to enhanced gas selectivity.