Spacer-Modulated Aggregation of the Cyanine Dye on the Vesicles of Gemini Amphiphiles

• Published in: Langmuir Vol. 25; no. 3; pp. 1366 - 1370
• Main Authors: Zhang, Guocheng, Zhai, Xiaodong, Liu, Minghua, Tang, Yalin, Huang, Xu, Wang, Yilin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.02.2009
• Subjects: Carbocyanines - chemistry; Chemistry; Colloidal state and disperse state; Colloids: Surfactants and Self-Assembly, Dispersions, Emulsions, Foams; Exact sciences and technology; General and physical chemistry; Membranes; Molecular Structure; Nanoparticles - chemistry; Particle Size; Solutions; Surface physical chemistry; Water - chemistry; X-Ray Diffraction; Aggregation; Vesicle; Transmission electron microscopy; Hydrocarbon; Adsorption; Dynamics; Film; Light scattering; Alkane; Aqueous solution; Aggregate; Cyanine dye
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la803557e

A series of gemini amphiphiles (bis(2′-heptadecyl-3′-ethylimidazolium)-1,n-alkane dibromide, abbreviated as Gn, n = 2, 4, 6, 8, 10) was found to form vesicles under ultrasonication in aqueous solution at very low concentration (5 μM), which was confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The adsorption and interaction of a cyanine dye (3,3′-disulfopropyl-4,5,4′,5′-dibenzo-9-methyl-thiacarbocyanine triethylammonium salt, abbreviated as MTC) on the vesicles was investigated. It was found that the cyanine dye could exhibit different colors when interacting with the vesicles. The UV−vis spectral measurements revealed the formation of the H or J aggregates of the cyanine dye on the vesicles, which is spacer length dependent: the short spacer length prefers the formation of the H-aggregate, whereas the longer spacer favors the J-aggregate formation. In addition, these aggregates showed different absorption positions from those on the planar films. Furthermore, by mixing the G2 and G10 vesicles in different ways, the selective aggregation of the cyanine dye on the vesicles was realized.