The design of Zr metal-organic frameworks in the detection and neutralization of organophosphorus based nerve agents and pesticides
Moore, Devin Scott
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Organophosphates are ubiquitous in uses ranging from chemical warfare agents (CWA’s) to detergents. In between these two extreme uses lie organophosphorus-based agrichemicals, primarily pesticides, which are applied in multi-tonne amounts each year. Metal-organic frameworks, especially the UiO-6x family, are known to interact, sequester, and/or break down organophosphate nerve gases. This thesis presents the synthesis and characterization of UiO-6x MOFs, comparing standing solvothermal with microwave methods, which appear (by powder Xray diffraction, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance (SS-NMR) analysis) to give equally high-quality products. Preparation of the UiO-6x MOFs were conducted using 1 molar equivalent of ZrCl4 to 1 equivalent of organic ligand in the presence of equal volumes of dimethyl formamide (DMF) and glacial acetic acid (GAA) for both solvothermal and microwave methods. Yields ranged from 41-63% for our synthesized MOFs (UiO-66, UiO-67 and UiO-67-bipy). The prepared MOFs are then reacted with organophosphate nerve agent simulants and agrichemicals in reactions followed by GC or HPLC; it appears that the studied agrichemicals are less-reactive than their chemical warfare agent equivalents with only (2-chloroethyl) phosphonic acid and glyphosate showing reactivity with UiO-67 and UiO-66 respectively whereas UiO-67-bipy was shown to nearly completely degrade/sequester dimethyl methylphosphonate. Also presented are preliminary SSNMR spectra on UiO-66 post-reaction with glyphosate. The line-broadening and restricted rotation that occurs on the combined spectrum suggests the pesticide is incorporated whole into the MOF without degrading.