Fig. 1. Representation of conventional liquids, which do not contain permanent intrinsic porosity, compared to the four proposed types of porous liquids: type I – neat molecular species containing permanent pores which are liquid at room temperature or low-melting; type II – solutions of microporous materials in cavity-excluded solvents; type III – dispersions of microporous solids in cavity-excluded liquids; and type IV – neat meltable microporous extended frameworks.