Controlling gas selectivity in molecular porous liquids by tuning the cage window size.

Control of pore window size is the standard approach for tuning gas selectivity in porous solids. Here, we present the first example where this is translated into a molecular porous liquid formed from organic cage molecules. Reduction of the cage window size by chemical synthesis switches the selectivity from Xe-selective to CH4-selective, which is understood using Xe-129, H-1, and pulsed-field gradient NMR spectroscopy.