Holey Liquid, Batman!

Abstract

How is a new type of liquid like the London Underground? In both, one must mind the gaps. Stuart James of Queen’s University Belfast and coworkers have devised a liquid with permanent porosity (Nature 2015, DOI: 10.1038/nature16072). Such holey fluids could be useful in gas separation, process chemistry, and other applications, if they can be made economically. Their persistent porosity comes from hollow organic cage molecules coated with solvent-soluble surface groups. The cage openings are too small to be clogged by the surface groups or by large solvent molecules in the surrounding solvent. Liquids contain spaces between their molecules, but they are tiny. Bubbles can be blown into liquids, but they will quickly float to the surface and dissipate—air bubbles in glass being a rare exception. On the other hand, solids such as zeolites and metal-organic frameworks have permanent pores. They can be used to separate molecules by size and ...