Hierarchical self-assembly of amphiphilic calix[6]arene wheels and viologen axles in waterDedicated to Prof. Maurizio Prato on the occasion of his C60th birthday.Electronic supplementary information (ESI) available: NMR spectra, UV-visible titration experiments, determination of critical aggregation concentration, Cryo-TEM, 5(6)-carboxyfluorescein (CF) release and DLS analysis of CA8 and CA18 aggregates. See DOI: 10.1039/c3ob40739j

We have designed and synthesized two amphiphilic calix[6]arene derivatives, CA8 and CA18 , that combine the potential to act as wheel components for pseudorotaxane structures with the self-assembly features typical of surfactant molecules in aqueous solution. Their endo-cavity recognition and self-aggregation properties were compared with those of a non-amphiphilic analogue, C8 . TEM, DLS, and fluorescence experiments show that in water the amphiphilic calixarenes form vesicle- and micelle-like aggregates. The size, nature and properties of such aggregates depend on the length of the alkyl chain anchored at the lower rim of the calix[6]arene skeleton, as well as on the inclusion of a molecular guest into the wheel. Specifically, the release of a fluorescent guest entrapped inside the CA8 vesicles is accelerated in the presence of dioctylviologen axles that can pierce the calixarene cavity. Amphiphilic calix[6]arenes self-assemble in water to generate micelles or vesicles; the formation of pseudorotaxanes with viologens increases the vesicles permeability, triggering the release of their content.