Zhang Guocheng, Zhai Xiaodong, Liu Minghua, Tang Yalin, Zhang Yazhou
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Science, 100080, Beijing, People's Republic of China.
J Phys Chem B. 2007 Aug 9;111(31):9301-8. doi: 10.1021/jp071515g. Epub 2007 Jul 18.
The aggregation of dyes is of considerable importance in relating to their functions and applications. In this paper, we have investigated the regulation on the aggregation and morphology of two cyanine dyes, 3,3'-disulfopropyl-4,5,4',5'-dibenzo-9-methylthiacarbocyanine triethylammonium salt (MTC) and 3,3'-disulfopropyl-4,5,4',5'-dibenzo-9-phenylthiacarbocyanine triethylammonium salt (PTC), using a series of gemini amphiphiles (bis(2'-heptadecyl-3'-ethylimidazolium)-1,n-alkane dibromide, abbreviated as Gn, n=2, 4, 6, 8, 10). It has been found that both of the dyes could be adsorbed onto the monolayers of the gemini amphiphiles through the electrostatic and pi-pi interaction and stacked into H- or J-aggregate. The spacer of the gemini amphiphile showed good control over the aggregation of MTC: H-aggregate was favored when gemini amphiphiles with short spacer were applied, while J-aggregation was preferred in the case of longer spacer. Only J-aggregate was observed for PTC on gemini monolayer, regardless of the structure of the gemini amphiphiles. Interesting morphologies were observed for all the gemini/dye complex monolayers. Network structure and nanofibers were formed for the gemini/MTC films transferred below the plateau surface pressure and close to the collapse pressure, respectively. The ability of the complex monolayers to form nanofibers strongly depended on the component amphiphiles, G2>G4>G6, and no nanofibers were observed for G8/MTC and G10/MTC after the collapse. Only squared domains were observed for gemini/PTC monolayers. When both G2 and G10 were mixed, an individual control of the gemini amphiphiles over the aggregation of MTC in the complex monolayers was observed. The relationship among the spacer, dye structure, and aggregation was revealed.
染料的聚集对于其功能和应用具有相当重要的意义。在本文中，我们使用了一系列双子表面活性剂（双（2'-十七烷基-3'-乙基咪唑鎓）-1,n-烷二溴化物，简称为Gn，n = 2、4、6、8、10）研究了对两种花青染料3,3'-二磺丙基-4,5,4',5'-二苯并-9-甲基硫代碳菁三乙铵盐（MTC）和3,3'-二磺丙基-4,5,4',5'-二苯并-9-苯基硫代碳菁三乙铵盐（PTC）聚集和形态的调控。研究发现，两种染料均可通过静电和π-π相互作用吸附到双子表面活性剂的单分子层上，并堆积成H-或J-聚集体。双子表面活性剂的间隔基对MTC的聚集表现出良好的控制作用：使用短间隔基的双子表面活性剂时有利于形成H-聚集体，而间隔基较长时则更倾向于形成J-聚集体。在双子表面活性剂单分子层上，无论双子表面活性剂的结构如何，PTC仅观察到J-聚集体。对于所有双子/染料复合单分子层，均观察到有趣的形态。对于在低于平台表面压力且接近崩溃压力下转移的双子/MTC薄膜，分别形成了网络结构和纳米纤维。复合单分子层形成纳米纤维的能力强烈依赖于组成表面活性剂，G2>G4>G6，崩溃后G8/MTC和G10/MTC未观察到纳米纤维。对于双子/PTC单分子层，仅观察到方形区域。当G2和G10混合时，观察到双子表面活性剂对复合单分子层中MTC聚集的单独控制作用。揭示了间隔基、染料结构和聚集之间的关系。
