Synthesis and Self-assemblies of Cascade Molecules with Aromatic π-Electronic System As a Core

点击翻译按钮获取中文摘要

A series of bolaamphiphilic cascade molecules, in which spherical dendritic hexa-alcohols end groups were separated by hydrocarbon lipophilic core, were synthesized from hydroquine in three steps. The O-alklation of hydroquinone with α,ω-dibromoalkanes in the presence of KィイD22ィエD2COィイD23ィエD2 in refluxing acetonitrile afforded the corresponding 1,4-bis(bromoalkoxy)benzenes. The dibromides reacted with dimethyl malonate in the presence of KィイD22ィエD2COィイD23ィエD2 in DMF to yield the tetraesters. The reaction of the tetraesters with tris(hydroxymethyl)aminomethane gave new bolaamphiphilic cascade molecules 1 with six hydroxyl end groups. The amphiphilic cascade molecules 2 possessing six hydroxyl end group were also prepared from phenol. Gelation was examined by adding the cascade molecules to water and heating the mixture to obtain a clear solution, followed by cooling to room temperature. The bolaamphiphilic cascade molecules 1 with methylene length (CHィイD22ィエD2)ィイD2nィエD2 n=4, 6, 8 caused gelation. However, the bolaamphiphilic cascade molecule 1 with methylene length n=10 and the amphiphilic cascade molecules 2 obtained from phenol did not form gel. Electron micrographs of the gel revealed the presence of numerous fibers.