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Digitale Medien

Substrate binding to cyclodextrins in aqueous solution: A multicomponent self-diffusion study (1983)

Rymdén, Roger ; Carlfors, Johan ; Stilbs, Peter

Springer

Journal of inclusion phenomena and macrocyclic chemistry 1 (1983), S. 159-167

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ISSN: 1573-1111

Schlagwort(e): Cyclodextrin ; Self-Diffusion ; Nuclear Magnetic Resonance ; Inclusion-Complex ; Hydrophobic Interaction ; Alcohols

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract It is demonstrated that substrate binding to α- and β-cyclodextrins (CD) in solution can conveniently and directly be monitored from multicomponent self-diffusion data on these solutions, using the Fourier Transform NMR pulsed-gradient spin-echo technique. Included are aromatics and a series of alcohols ranging from methanol to octanol. Experimentally it was found thatn-alcohols associate more strongly with α-CD than with β-CD. As the bulkiness of the alcohol increased, binding to β-CD was enhanced while the reverse effect was observed in the case of α-CD. For both cyclodextrins it was found thatn-alcohol complexation in the homologous series was attributable to an increment in standard free energy of complexation of ∼ −3.0 kJ/mol for each −CH2− group, suggesting that the binding mechanism is of a hydrophobic nature.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00656818

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Digitale Medien

Friction coefficients in self-diffusion, velocity sedimentation, and mutual diffusion for poly(ethylene oxide) in aqueous solution (1983)

Brown, Wyn ; Stilbs, Peter ; Johnsen, Robert M.

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1029-1039

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ISSN: 0098-1273

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The concentration dependences of the friction coefficient(s) for poly(ethylene oxide) have been determined on well-defined fractions in dilute aqueous solution. Three independent techniques have been used: FT-pulsed field gradient NMR (self-diffusion), photon correlation spectrosccpy (mutual diffusion), and velocity sedimentation, in the concentration range 1-25 kg m-3. The results establish that, at a given concentration, the friction coefficient in self-diffusion is appreciably smaller than that operating in mutual diffusion and sedimentation; the friction coefficient in the latter processes are identical within experimental error.

Zusätzliches Material: 9 Ill.