| Summary: | 博士 === 國立臺灣師範大學 === 化學系 === 99 === We have developed directed encapsulation of metal metavandate (MVO3-2H2O) by tailor-made, chiral oxidovanadium(V) methoxides with concomitant formation of C4-symmetric vanadate-centered clusters. This artificial, directed evolution process in chiral vanadyl(V) complex allows for highly efficient K+-, Ba2+-, Hg2+- and MeNH3+-specific transport from aqueous phase containing other alkali metal cations, alkaline-earth matal cations, heavy metal cations and ammonium cations respectively, into organic solvents. The X-ray crystal structures of 1-K, 1-Cs, and 1-Ag revealed distorted square planar geometry around the binding site which are in close similarity to the K+ transport mode exerted by four homochiral glycine residues of the opening site in KcsA. For the +2 cation cases, the X-ray crystal structures of 1-Ba and 2-Ba existed as a unique 2:1 sandwich like complexes between the C4-vanadate in order to fulfill the ionic charge interaction and charge balance between Ba2+ and the central vanadate. On the other hand, 2-Pb and 3-Hg displayed a square planar binding mode topped with a nitrate ligand to form a trigonal prism cage. Beside the synergistic metal ion-specific transport, we also found that the Li+ and Na+ encapsulated clusters can effect a highly enantioselective aerobic oxidation of racemic S-benzyl-thiomandelate with complete kinetic resolution in a synergistic mode.
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