We just published our most recent results in J. Am. Chem. Soc., using ozone for an unprecedented post synthetic merging of micropores into mesopores in MOFs.
By a careful selection a pair of organic ligands with similar length and shape, we created multivariate Zr-fcu-MOFs. The specificity of one of the ligands versus the other is the presence of one or two olefin bonds, readily cleavable in ozone atmosphere.
Cleaving and removing this ligand, while the other remains untouched allows to play with the porosity, to tune it in order to merge micropores into mesopores. But that’s not all. A very cool feature is that we were also able to extract some organic parts from the framework, by a sublimation, deposition process. Almost like fine surgery!
The articles describes it in details, check it out!
Abstract: Herein we report a novel, ozone-based method for post-synthetic generation of mesoporosity in metal-organic frameworks (MOFs). By carefully selecting mixed-ligand Zr-fcu-MOFs based on organic ligand pairs in which one ligand has ozone-cleavable olefin bonds and the other ligand is ozone-resistant, we were able to selectively break the cleavable ligand via ozo-nolysis to trigger fusion of micropores into mesopores within the MOF framework. This solid-gas phase method is performed at room-temperature and, depending on the cleavable ligand used, the resultant ligand-fragments can be removed from the ozonated MOF by either washing or sublimation. Compared to the corresponding highly-microporous starting MOFs, the highly-mesoporous product MOFs exhibit radically distinct gas sorption properties.