When compared to distillations, separation procedures utilizing porous materials can save 70-90 % of energy expenses. IPMs are a subclass of porous molecular materials made up of molecular host macrocycles or cages that absorb guests in or around their intrinsic cavity. IPMs range from single porosity molecules to amorphous or highly crystalline held together by weak supramolecular connections. IPMs have good host-guest behaviors in solid, liquid (organic or aqueous), and gas phases, which may be used to build various separation methods such as solid-gas adsorption, solid-liquid absorption, and liquid-liquid extraction. We give a new perspective on the application of intrinsically porous materials such as cucurbiturils, trianglamines, and organic cages, which shown outstanding performance in gas purification and benzene derivative separation. IPMs relatively stable, and solution processable, facilitating a favorable technical transition away from existing energy-intensive separations. We will discuss the major developments in molecular host-guest chemistry that have enabled us to create "on-demand" separation methods.