The apparent pKa of the 7-hydroxycoumarin (Umbelliferone) was spectrophotometrically measured in a Water/AOT/Isooctane microemulsion in the presence of Tris, Ammonia, and Carbonate buffer solutions. The apparent pKa increases of about 2 units, in comparison with the pKa measured in bulk water, for the smallest values of the molar ratio Water/AOT, and decreases with the radius of the nanodroplets. The results are discussed taking into account the profile of the electrical potential drop into the water pool and the possible partition of the Umbelliferone between the aqueous core and the surfactant.
PH in reverse micelles: The acid dissociation constant of the 7-hydroxy coumarin in Water/AOT//Sooctane water-in-oil microemulsions
Caselli M.
;Mangone A.;Traini A.
1998-01-01
Abstract
The apparent pKa of the 7-hydroxycoumarin (Umbelliferone) was spectrophotometrically measured in a Water/AOT/Isooctane microemulsion in the presence of Tris, Ammonia, and Carbonate buffer solutions. The apparent pKa increases of about 2 units, in comparison with the pKa measured in bulk water, for the smallest values of the molar ratio Water/AOT, and decreases with the radius of the nanodroplets. The results are discussed taking into account the profile of the electrical potential drop into the water pool and the possible partition of the Umbelliferone between the aqueous core and the surfactant.File in questo prodotto:
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