1H NMR Studies of Aerosol-OT Reverse Micelles with Alkali and Magnesium Counterions: Preparation and Analysis of MAOTs

详细信息    查看全文

• 作者：Michelle L. Stahla ; Bharat Baruah ; Dustin M. James ; Michael D. Johnson ; Nancy E. Levinger ; Debbie C. Crans
• 刊名：Langmuir
• 出版年：2008
• 出版时间：June 17, 2008
• 年：2008
• 卷：24
• 期：12
• 页码：6027 - 6035
• 全文大小：163K
• 年卷期：v.24,no.12(June 17, 2008)
• ISSN：1520-5827

文摘

Simple procedures and characterization of a series of well-defined precursors are described for preparation of a unique microenvironment in nanoreactors, reverse micelles. The Na⁺, K⁺, Rb⁺, Cs⁺, and Mg²⁺ surfactants were prepared using liquid–liquid ion exchange using chloride and nitrate salts. The surfactants were characterized using ¹H NMR spectroscopy and a variety of other techniques. ¹H NMR spectroscopy was found to be a sensitive probe for characterization of the size of the nanoreactor as well as its water content. ¹H NMR spectra can be used for detailed characterization of reactions in confined environments when counterion effects are likely to be important. ¹H NMR spectroscopy revealed two separate peaks corresponding to water in Mg(AOT)₂ samples; one peak arises from water coordinated to the Mg²⁺ ion while the other peak arises from bulk water. The two water signals arise directly from the slow exchange of the water coordinated to Mg²⁺ in these microemulsions with water in the water pool, and provide an opportunity to study hydration of Mg²⁺. This work thus extends the potential use of MAOT microemulsions for applications such as in green chemistry.