Contract W911NF-07-1-0139 (Massachusetts Institute of Technology)
Abstract
Porous inorganic or metal-organic materials with crystalline coordination structures and diverse topologies can be functionalized by inclusion of organic molecules. Specialized meso- and nanoporous matrices such as clays and metal-organic frameworks (MOF) possess sufficient mechanical, thermal, and chemical stability to yield promising materials when functionalized by organic ligands via inclusion of the ligands into the pores using supramolecular host guest chemistry. Our work has focused on hybrid materials suitable for protection against organophosphorous toxicants. Specifically, mesoporous matrices such as acidic montmorillonite K-10 and nanoporous chromium (III) terephthalate-based MOF (MIL-101) with multiple coordinatively unsaturated metal sites with Lewis acid properties were modified by inclusion of ?-nucleophilic or supernucleophilic, basic ligand molecules such as 2-pralidoxime (PAM) and dimethylaminopyridine (DMAP), respectively. The resulting functionalized materials were effective in nucleophilic degradation of organophosphorous (OP) esters represented by CWA simulants and pesticides. Studies demonstrated that upon inclusion into the montmorillonite interlayer structure, the pyridinium group of sodium pralidoximate is strongly physisorbed onto acidic sites of the clay, leading to shrinking of the interplanar distance. Analogously, sorption of DMAP leads to changes in the MIL-101 structure, as demonstrated by X-ray diffractometry and FTIR. Degradation of diethyl parathion by the functionalized materials in aqueous-acetonitrile solutions occurred via hydrolytic conversion of parathion into diethylthio phosphoric acid, whereas hydrolytic degradation of diisopropyl fluorophosphate (DFP), a CWA simulant, was observed by 31P HRMAS to be rapid compared with these reactions in the untreated montmorillonite or MOF.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 09, 2013
- Accession Number
- ADA591208
Entities
People
- T. A. Hatton
Organizations
- Massachusetts Institute of Technology