Switchable Supramolecular Organization of Structurally Defined Micelles Based on an Amphiphilic Fullerene

摘要

Some time ago we started to investigate the synthesis and supramolecular organization of dendritic amphiphiles that contain fullerenes or calixarenes as core units.[1]-[3] Apart from the synthesis of structurally persistent micelles, we were particularly interested in the assembly of functionalized micelles and liposomes in order to direct the aggregation behavior of these species with an appropriate external stimulus. Results from these studies could be useful for the development of drug-delivery systems. Examples of such dendritic amphiphiles include the globular amphifullerene 1,[1] which contains a pair of carboxy-terminated amide dendrons and five dodecyl malonate addends attached to the fullerene core in an octahedral [1:5] addition pattern, and the calixarene derivative 2,[3] which contains analogous hydrophilic and lipophilic units. In amphiphile 1 the space required for the hydrophilic and the hydrophobic areas is balanced whereas the extended chains have free conformational mobility. This ensures a wide spectrum of energetically favorable packing motifs both for the formation of micellar structures and for extended liposomal double layers. The existence of different aggregates was confirmed by electron microscopic investigations.[2a]