Twisted Frameworks

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Science  12 Oct 2001:
Vol. 294, Issue 5541, pp. 269
DOI: 10.1126/science.294.5541.269b

Molecule-scale porosity has typically been associated with inorganic materials such as zeolites. Recently, much progress has been made in synthesizing metal-organic frameworks that resemble zeolites not only in porosity but also in thermal and hydrolytic stability. An additional feature of metal-organic frameworks is that their more rational synthesis should allow for greater tailoring of their properties.

Evans et al. precipitated lanthanide salts with chiral binaphthalene ligands bearing two phosphonate groups. The resulting compounds crystallized in a chiral lamellar structure with large (∼12 angstrom) asymmetric channels. After the removal of included water molecules, the crystals could be used for separations of racemic mixtures of organic molecules. Although separation efficiencies are still modest (∼10% enantiomeric excess), the controlled route of synthesis should allow rational improvement in these materials for chiral separations and for asymmetric catalysis.—PDS

J. Am. Chem. Soc. 10.1021/ja0163772.

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