Zirconium based metal-organic frameworks (MOFs), such as the UiO family, are potential candidates for the degradation of chemical warfare agents (e.g. Soman) as well as their simulants. A critical evaluation of the activity of the precursors, e.g., metal salts (ZrCl4, HfCl4), under basic aqueous conditions reveals key mechanistic details of the hydrolysis of dimethyl nitrophenyl phosphate (DMNP), a simulant of Soman, by UiO MOFs. Using spectroscopic studies, we found that the metal precursors of MOFs drive the hydrolysis and confirmed that their activity is proportional to the Lewis acidity of the metal. We hypothesize that in situ hydrolysis of ZrCl4/HfCl4 to oxyhydroxides, after dissolution in basic aqueous medium, provides the necessary catalytic centers for the reaction. Our results support that the active site in UiO-67 MOFs responsible for the hydrolysis of DMNP is the metal node, and that Lewis acidity can guide researchers in clearly and rapidly choosing the optimum metals for synthesizing suitable metal organic frameworks for DMNP hydrolysis.

Tuning the Lewis acidity of metal-organic frameworks for enhanced catalysis

ACS Spring Meeting 2021

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