Frameworks Fight Chemical Weapons

With their ability to hydrolyze the phosphate ester linkages in chemical warfare agents, zirconium-based metal-organic frameworks, or MOFs, are being eyed as materials for filters in gas masks and other decontamination equipment. Now two groups are reporting improvements on this technology. Chemists in Spain, led by the University of Granada’s Jorge A. R. Navarro and Elisa Barea, boosted the hydrolytic powers of MOF UiO-66 by incorporating lithium alkoxide in its structure (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201502094). The researchers wove this modified version of UiO-66 into a textile by spraying a suspension of the MOF onto silk fibroin fibers. In other work, Northwestern University chemists led by Omar K. Farha and Joseph T. Hupp explored a newer kind of Zr-based MOF—dubbed MOF-808—that can hydrolyze stand-ins for chemical warfare agents 350 times as fast as UiO-66 (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201502155). UiO-66 uses a dozen small organic connectors to bridge its Zr nodes; MOF-808 uses only six organic connectors to link Zr nodes. The difference leads to more reactive nodes as well as wider channels in MOF-808, which chemical warfare agents enter more easily.