Micellization-Induced Conformational Change of a Chiral Proline Surfactant

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• 作者：Manli Deng ; Xu Huang ; Rongliang Wu ; Yilin Wang
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：August 28, 2008
• 年：2008
• 卷：112
• 期：34
• 页码：10509-10513
• 全文大小：200K
• 年卷期：v.112,no.34(August 28, 2008)
• ISSN：1520-5207

文摘

A proline surfactant including two chiral carbons, sodium N-dodecanoyl-(4R)-hydroxy-L-prolinate (SDHP), has been synthesized, and its micellization behavior in aqueous solution has been investigated by ¹H NMR spectroscopy. Two conformational isomers of SDHP, namely, Z and E, are discriminated in the NMR time scale, and critical micelle concentration is derived for each isomer separately. The transformation from E to Z is observed upon micellization, and the amount of Z isomer is approximately three times that of E isomer in the equilibrated system. Moreover, the variation in chemical shifts with the surfactant concentration reveals the shielding effect of the carboxyl group on the syn-side protons of the pyrrolidine ring, which implies that the pyrrolidine rings arrange in a side-to-side manner and lie parallel to the plane of the carboxyl bonds in the neighboring molecules. The difference in the directions of the carbonyl group between Z and E isomers essentially determines their different micellization abilities and molecular arrangements in the micellization process.