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- Title
Coordination‐Cage‐Catalysed Hydrolysis of Organophosphates: Cavity‐ or Surface‐Based?
- Authors
Taylor, Christopher G. P.; Metherell, Alexander J.; Argent, Stephen P.; Ashour, Fatma M.; Williams, Nicholas H.; Ward, Michael D.
- Abstract
The hydrophobic central cavity of a water‐soluble M8L12 cubic coordination cage can accommodate a range of phospho‐diester and phospho‐triester guests such as the insecticide "dichlorvos" (2,2‐dichlorovinyl dimethyl phosphate) and the chemical warfare agent analogue di(isopropyl) chlorophosphate. The accumulation of hydroxide ions around the cationic cage surface due to ion‐pairing in solution generates a high local pH around the cage, resulting in catalysed hydrolysis of the phospho‐triester guests. A series of control experiments unexpectedly demonstrates that—in marked contrast to previous cases—it is not necessary for the phospho‐triester substrates to be bound inside the cavity for catalysed hydrolysis to occur. This suggests that catalysis can occur on the exterior surface of the cage as well as the interior surface, with the exterior‐binding catalysis pathway dominating here because of the small binding constants for these phospho‐triester substrates in the cage cavity. These observations suggest that cationic but hydrophobic surfaces could act as quite general catalysts in water by bringing substrates into contact with the surface (via the hydrophobic effect) where there is also a high local concentration of anions (due to ion pairing/electrostatic effects).
- Subjects
HYDROPHOBIC surfaces; PHOSPHAMIDON; CHEMICAL warfare agents; HYDROLYSIS; HYDROPHOBIC interactions; BINDING constant; CHLORPYRIFOS; ION pairs
- Publication
Chemistry - A European Journal, 2020, Vol 26, Issue 14, p3065
- ISSN
0947-6539
- Publication type
Academic Journal
- DOI
10.1002/chem.201904708