Synergistic ramifications of synthesis criteria and amine functionalization of UiO-66-NH2 MOFs for the catalytic degradation of a nerve agent simulant, methyl-paraoxon

Abstract

The malfeasant usage of chemical warfare agents (CWAs) involved in the current world praxis poses a threat to humankind. Owing to their acute lethal toxicity, the pursuit of favorable approaches for their detoxification/degradation is making continuous progress. With this background, a series of UiO-66-NH₂ metal–organic frameworks (MOFs) featuring structural defects were synthesized using a solvothermal technique by varying the modulator pK_a, HCl modulator concentration, synthesis temperature and ligand ratio. The present study contributes additional evidence that the considered synthesis parameters outweigh the creation of an open framework in its own metrics. By fine tuning the synthesis practices, the formation of structural defects has been greatly induced. Furthermore, the impact of structural defects possessed by the synthesized samples was systematically investigated against methyl-paraoxon (DMNP), a CWA simulant. The coexistence of an amine group (–NH₂) representing Brønsted basic sites, and Lewis acid sites of metal clusters in UiO-66-NH₂ reveals a maximum conversion efficiency up to 93.6% with an ultrafast transient degradation rate (k) and shorter half-lives of 1.567 min⁻¹ and 0.44 min, respectively.