I&EC 97 |
| Supramolecular architectures found in nature have inspired the design, synthesis and use of nanoscale molecular flasks formed through self-assembly from simple metal and ligand components. The metal-ligand complexes are highly negatively charged and very water soluble. However, they have hydrophobic interiors of about 0.5 nm3 that strongly and selectively encapsulate hydrophobic cationic guests. Because of tris-bidentate chelation at the metal vertices and the mechanical linkage between the metal vertices, these clusters are homochiral and resolvable. The structure, once resolved, can retain its chirality almost indefinitely. Encapsulation of reactive guests alters guest reactivity properties, and substantially modifies the basicity of guests where the acid species is encapsulated. The space restrictive cavity has also demonstrated its propensity to catalyze unimolecular rearrangements. By preferentially binding the substrates in reactive conformations, the metal-ligand assembly achieves order of magnitude rate accelerations. Release and hydrolysis of the product enable catalytic turnover.
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Molecular Containers, Sponsored by Separation Science and Technology Sub-Division
8:30 AM-12:15 PM, Monday, 11 September 2006 Moscone Center -- Room 250, Oral
Division of Industrial & Engineering Chemistry |