Ozonolysis enlarges MOF pores

Abstract

Metal-organic frameworks (MOFs)—porous materials made of organic linkers and metal bits stitched together into a meshlike structure—could catalyze reactions, detect chemicals, separate gases, and deliver drugs. The materials could be better fits for those applications if chemists could enlarge MOF pores from the microporous (under 2 nm) range into the mesoporous (2 to 50 nm) range, but existing methods of doing so are difficult or expensive. Now researchers have shown a way to clip off organic ligands in MOFs to turn micropores into mesopores (J. Am. Chem. Soc. 2018, DOI: 10.1021/jacs.8b09682). Daniel Maspoch of the Catalan Institute of Nanoscience & Nanotechnology and colleagues made MOFs with zirconium clusters and two ligands, azobenzene-4,4’-dicarboxylic acid and 4,4’-stilbenedicarboxylic acid (H2sti). Ozone can selectively snip off the H2sti ligands. Before adding ozone to the MOFs, the pores were about 1.5 nm in diameter. Afterward, they ranged from 2 to 5 nm in diameter. Omar