How inorganic anions affect the inclusion of hexanoic and decanoic acid in beta-cyclodextrin
authors Lima, S; Goodfellow, BJ; Teixeira-Dias, JJC
nationality International
journal JOURNAL OF PHYSICAL CHEMISTRY A
keywords AQUEOUS-SOLUTIONS; BASIC HYDROLYSIS; MICELLAR MEDIA; COMPLEXATION; H-1-NMR; SURFACTANTS; THERMODYNAMICS; MICELLIZATION; DIFFRACTION; SCATTERING
abstract NMR chemical shift variations of beta-cyclodextrin (betaCD) H5 protons are used as probes in various experiments in which the initial concentrations of decanoic or hexanoic acids and/or of various sodium salts (NaCl, NaBr, NaClO4, NaNO3) are varied. The host-guest systems are considered to be in the NMR fast exchange chemical shift limit, and the slopes of the measured chemical shift variations as functions of the mole fractions of the free and complexed states, Deltadelta(i)(o) = (deltaDeltadelta/deltax(i))(xj(jnot equali)), are determined in a systematic way using experiments delineated for that purpose. The evaluated Deltadelta(o) coefficients provide quantitative interpretations of the shielding due to the inclusion of the amphiphilic guests in betaCD and the deshielding resulting from the inclusion of hydrated anions in betaCD. The influence of the amphiphilic guests on the inclusion of the hydrated anions in betaCD and vice versa is also evaluated. By recording the chemical shift changes of the methyl protons of decanoic acid in a carefully delineated experiment, the Ad coefficients for the aggregation and inclusion of decanoic acid were obtained. A shielding effect was observed for both of these processes although a relative deshielding effect was found for the inclusion in betaCD relative to decanoic acid aggregation.
publisher AMER CHEMICAL SOC
issn 1089-5639
year published 2004
volume 108
issue 46
beginning page 10044
ending page 10049
digital object identifier (doi) 10.1021/jp046882w
web of science category Chemistry, Physical; Physics, Atomic, Molecular & Chemical
subject category Chemistry; Physics
unique article identifier WOS:000225079100003
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