Langmuir Monolayer and Langmuir−Blodgett Films Formed by a Melamine-Headed Azobenzene-Derived Amphiphile: Interfacial Assembly Affected by Host−Guest Interaction

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• 作者：Weihong Xu^&#8224 ; ; Yanhua Wang^&#8224 ; ; Yunxia Xiao^&#8224 ; ; Fang Liu*^&#8224 ; ^‡ ; ; Guo-Yuan Lu*^&#8224 ;
• 刊名：Langmuir
• 出版年：2009
• 出版时间：March 17, 2009
• 年：2009
• 卷：25
• 期：6
• 页码：3646-3651
• 全文大小：163K
• 年卷期：v.25,no.6(March 17, 2009)
• ISSN：1520-5827

文摘

A novel azobenzene-derived amphiphile with a melamine head, 2Azo-2C₁₂H₂₅-melamine, has been synthesized. π−A isotherm measurements displayed that this amphiphile is able to form a stable Langmuir monolayer on both pure water and barbituric acid (BA)- or thymine (T)-containing subphases. The collapse surface pressure and limiting molecular area of its Langmuir monolayer on pure water are 40 mN/m and 0.56 nm², respectively. However, when barbituric acid or thymine was introduced into the subphase, the corresponding π−A isotherms of the monolayers exhibited a lower collapse surface pressure (22 mN/m for BA, 21 mN/m for T) and smaller limiting molecular area (0.54 nm² for BA and 0.52 nm² for T). UV−vis and FT-IR studies of the LB films formed by 2Azo-2C₁₂H₂₅-melamine have also been carried out. The results indicated that the LB films of 2Azo-2C₁₂H₂₅-melamine deposited from pure water undergo distinct collapse of the H-aggregate upon UV irradiation, while the LB films deposited from a BA- or T-containing subphase retain the H-aggregate. The host−guest-interaction-induced blockage of azobenzene photoisomerization should be responsible for the stabilized H-aggregate. A 1:1 host/guest binding mode to form a linear supramolecular polymeric chain has been proposed in the Langmuir monolayers formed on a BA- or T-containing subphase. The current results suggest that the host−guest interaction should be an effective means to manipulate the interfacial assembly of azobenzene-derived amphiphiles.