Study of the Interaction between a Nonyl Phenyl Ether and -Cyclodextrin: Declouding Nonionic Surfactant Solutions by
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- 作者：André ; s Guerrero-Martí ; nez ; Teresa Montoro ; Montserrat H. Viñ ; as ; Gustavo Gonzá ; lez-Gaitano ; Gloria Tardajos
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：February 15, 2007
- 年：2007
- 卷：111
- 期：6
- 页码：1368 - 1376
- 全文大小：339K
- 年卷期：v.111,no.6(February 15, 2007)
- ISSN：1520-5207
文摘
Absorption and fluorescence measurements for aqueous solutions at 298 K containing pentaoxyethylene nonylphenyl ether (NPE5), in the absence and presence of 
-cyclodextrin (-CD), were analyzed to determine theeffect of the complexation on the aggregation of the surfactant. For the binary system, the appearance of anew emission band and the presence of an isoemissive point in the emission spectra at the time and frequencydomains indicate the formation of an excimer within the micellar core. The addition of -CD induces theformation of an inclusion complex strong enough to break the aggregates and avoid the excimer formation.For the ternary system, the increase in fluorescence has been used to assess the binding constants of 1:1 +2:1 stoichiometries. Static light scattering, 1H NMR diffusion-ordered spectroscopy (DOSY), and two-dimensional rotating-frame Overhauser enhancement spectroscopy (ROESY) experiments were used tocharacterize the cloud point of NPE5 at 298 K, and to ascertain the effects of complexation on the cloudingprocess. In the presence of -CD, the analysis of the 1H NMR spectra and the self-diffusion coefficientsreveal the existence of interactions between the -CD and the aggregates that increase the cloud-pointconcentration more than expected. Under conditions of excess of -CD, ROE enhancements point to a complexof dominant 2:1 stoichiometry (-CD:NPE5) in which the hydrophobic moiety of the surfactant threads two-CDs.
-cyclodextrin (-CD), were analyzed to determine theeffect of the complexation on the aggregation of the surfactant. For the binary system, the appearance of anew emission band and the presence of an isoemissive point in the emission spectra at the time and frequencydomains indicate the formation of an excimer within the micellar core. The addition of -CD induces theformation of an inclusion complex strong enough to break the aggregates and avoid the excimer formation.For the ternary system, the increase in fluorescence has been used to assess the binding constants of 1:1 +2:1 stoichiometries. Static light scattering, 1H NMR diffusion-ordered spectroscopy (DOSY), and two-dimensional rotating-frame Overhauser enhancement spectroscopy (ROESY) experiments were used tocharacterize the cloud point of NPE5 at 298 K, and to ascertain the effects of complexation on the cloudingprocess. In the presence of -CD, the analysis of the 1H NMR spectra and the self-diffusion coefficientsreveal the existence of interactions between the -CD and the aggregates that increase the cloud-pointconcentration more than expected. Under conditions of excess of -CD, ROE enhancements point to a complexof dominant 2:1 stoichiometry (-CD:NPE5) in which the hydrophobic moiety of the surfactant threads two-CDs.