ISSN:
1573-1111
Keywords:
β-Cyclodextrin
;
surfactants
;
inclusion complexes
;
NMR
;
surface tension
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The inclusion complexes of β-CD with sodium octylsulfonate (C8As), sodium dodecyl sulfonate (C12As), andsodium hexadecyl sulfonate (C16As) in aqueous solutions havebeen studied by surface tension measurement at the air/water interfaceand 1H NMR spectroscopy at 323 K. At fixed concentrations of the surfactants, the surface tensions firstincrease with the increase of β-CD concentrations,then they attain a maximum. The surface tension curves of the surfactantsin the presence of β-CD are higher than those in the absence ofβ-CD. The values increase with increasing β-CD concentrations foreach surfactant. The apparent critical micelle concentrations (CMC) of thesurfactants vary linearly with β-CD concentrations. A 1H NMR study shows that the signals of theinner H-3 and H-5 of β-CDshift upfield upon addition of the surfactants.The magnitude of the chemicalshift changes (Δδ=δ CDδ obs)varies as a functionof the concentrations of the surfactants. From therelationships between the chemicalshift changes of H-3 or H-5 inside the β-CD cavityand guest/host molar ratios, a 1:1 stoichiometry foreach inclusion complex is assumed. The associationconstants of the inclusion complexes have beendetermined by 1H NMR spectroscopy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007923723044
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