Anthropogenic greenhouse gases contribute to global warming. Among those gases, perfluorocarbons (PFCs) are thousands to tens of thousands times more harmful to the environment than comparable amounts of carbon dioxide. Till date, materials that selectively adsorb perfluorocarbons in favor to other less harmful gases have not been reported. Here a series of porous organic cage compounds with alkyl-, fluoroalkyl, and partially fluorinated alkyl groups are presented. Their isomorphic crystalline states allowed us to study the property-relationship of the degree of fluorination of the alkyl chains on gas sorption properties for PFCs and their selective uptakes in comparison to other, non-fluorinated gases. By this approach, one compound was identified, having superior selectivities of PFCs vs N2 or CO2 under ambient conditions.