Discrete and well-defined hydrophobic phases confined in self-assembled spherical complexes.

Introduction Long alkyl chains have a tendency to aggregate and form localized hydrophobic environments in polar solvent. This tendency has been exploited to prepare a variety of artificial structures, such as micelles, vesicles, core-shell structured polymers, and dendrimers, where the localized hydrophobic environments show interesting properties. These artificial long alkyl chain assemblies, as well as biomembranes, are typically structurally dispersed. The structural disparities result in a distribution of properties. Here we report discrete and well-defined assemblies of alkyl chains confined in a 5 nm spherical coordination shell (Fig. 1). The shell framework quantitatively assembles from 12 Pd ions and 24 bent ligands and sharply defines the boundary of the interior hydrophobic phase of long alkyl chains. Furthermore, the nature of hydrophobic interior can be easily tuned by varying length of the alkyl chains.