Micellar location of the solubilizate

The use of a probe molecule to study the properties of micellar medium requires the knowledge of the micellar binding site of the probe molecule, with absolute certainty under a specific condition, which is almost impossible to achieve by any experimental or theoretical technique. Pyrene, a highly hydrophobic water insoluble hydrocarbon molecule, has been used to determine the polarity of micellar medium, but its precise micellar binding site is not known with absolute certainty. For instance, pulsed Fourier transform NMR and chemical shift analyses used to determine the dynamic solubilization site of the pyrene in cationic micellar solutions show that pyrene is solubilized in the interior of the 

CTABr micelles. But other studies, which used different experimental techniques, conclude that pyrene does not reside in the micellar interior instead, it resides in a relatively polar miceUar environment, i.e., interfacial region. - Microviscosities of the six micelles (SDS, CTABr, 2-phenyldodecanesulfonate, 3-phenyldodecanesulfonate, 4-phenyldodecanesulfonate, and 6-phenyldodecane-sulfonate) have been obtained from the average reorientation times of two probes (2,5-dimethyl-l,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole and coumarin 6) in micelles, and it has been observed that both the probes sense almost identical microviscosity for a single micelle.  

The solubilizates of different effective hydrophobicity are expected to occupy different microregions of a micelle. The approximate assignment of the location of a solubilizate in the micelle depends very much upon the type of technique used for this purpose and the interpretation of the results obtained. For example, benzene molecules are concluded to exist close to the interface between hydrocarbon and water based upon H NMR chanical shift measurements in aqueous 

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