Interfacial Assemblies of Cyanine Dyes and Gemini Amphiphiles with Rigid Spacers: Regulation and Interconversion of the Aggregates

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• 作者：Guocheng Zhang ; Minghua Liu
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：June 26, 2008
• 年：2008
• 卷：112
• 期：25
• 页码：7430 - 7437
• 全文大小：2629K
• 年卷期：v.112,no.25(June 26, 2008)
• ISSN：1520-5207

文摘

A series of gemini amphiphiles with a pyridinium headgroup and rigid spacers were designed, and their interfacial assemblies with cyanine dyes, 3,3-disulfopropyl-9-methyl-selenacarbocyanine (SeCy) and 3,3-disulfopropyl-4,5,4′,5′-dibenzo-9-methyl-thiocarbocyanine (MTC), through the air/water interface were investigated. Although the dyes have intrinsic tendencies to form J- or H-aggregates in aqueous solutions, their aggregation could be regulated in the complex films. Depending on the spacer, both J- and H-aggregates were formed for SeCy, whereas an H-aggregate with different absorption bands was obtained for MTC. Furthermore, the formed aggregates in the films could be reversibly switched by treating the complex films with HCl, NH₃ gas, or water vapor. The J-aggregates of SeCy could be changed into H-aggregates and recovered through an alternative HCl/NH₃ exposure in the films. The H-aggregate of the MTC film could be changed into J-aggregate upon exposure to HCl gas and subsequently put into air or NH₃ gas, and the thus-formed J-aggregate could be changed into H-aggregate under hot water vapor. In addition, such a reversible switch between different aggregates of MTC was only observed when the gemini amphiphiles with rigid spacers were applied. A possible explanation related to the protonation of the dye and the reorganizations in the film during the interconversion between different aggregates was proposed.