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  • 1
    ISSN: 1573-1111
    Keywords: inclusion complex, β-cyclodextrin ; trisulfonated triphenylphosphine ; NMR spectroscopy ; electrospray mass spectroscopy ; UV-vis spectroscopy ; molecular modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of inclusion complexesbetween the sodium salt of trisulfonatedtriphenylphosphine and β-cyclodextrin has beeninvestigated at two temperatures by high field nuclearmagnetic resonance, electrospray mass and UV-visspectroscopies. At 268 K, titration experiments andJob's method suggest that the major species insolution is a 1 : 1 inclusion complex. The moleculargeometry of this inclusion complex was studied usingthe ROESY NMR technique complemented by molecularmodelling. All these methods converged towards thestructure attained by inserting one aromatic ring intothe hydrophobic cavity of the host from the side ofthe secondary hydroxyls. At 298 K, a higher proportionof 2 : 1 and 3 : 1 complexes induces strong alterations ofthe NMR signals, preventing an easy and reliabledetermination of association constants. Nevertheless,an apparent association constant can be determinedfrom UV-vis data by assuming a 1 : 1 equilibrium. Thegeometry of the 2 : 1 and 3 : 1 complexes is also brieflydiscussed from ROESY NMR experiments.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Cyclodextrins ; Two-phase catalysis/ Palladium ; Carbonates ; Substrate selectivity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalytic amounts of chemically modified β-cyclodextrins allowed us to achieve, in high yields, the deprotection of various water-insoluble allylic carbonates in a genuine two-phase system without co-solvent. The catalytic activities were up to 300 times higher than those observed without modified cyclodextrins. The process of molecular recognition between the cyclodextrin and the substrate allowed us to perform substrate-selective catalytic reactions which cannot be achieved in homogeneous or biphasic media with conventional transition metal catalysts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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