To further verify that the measured gas uptake is indicative of a PIL, we tracked the anions over the course of the simulation (Fig. ). Here, we observe that at any given time, ~86% of the NTf2 counterions are near a cage molecule (within 20 Å of the centre of a cage), ~13% reside in the bulk liquid phase (> 20 Å away from a cage centre), and ~0.09% are located at a cage window (~5.5 Å away from the cage centre). These cutoffs are determined by the geometry of the cage molecule. Importantly, no NTf2 counterions were observed to enter the cage cavity during the simulations. These results support the initial hypothesis that the NTf2 counterions are too large to diffuse into the [RCC1-IM] 6+ cavity, and the [RCC1-IM][NTf2]6 system is a PIL. Further, these results are similar to a previously published study where the location of the solvent hexachloropropene was tracked over the course of a porous liquid simulation featuring scrambled CC3 3 13 3 as the porous motif. Here, ~80% of solvent molecules reside in the bulk, ~16% reside near a neighbour, and 3% are located in a cage window. Full simulation analysis details for the [RCC1-IM][NTf2]6 system are presented in Table .