Metal Ion Transport Across Metal-organic Pyrogallol[4]arene-based Nanocapsules

The transport of ions across molecular cages that mimic the behavior of bio-membranes has been of wide interest to researchers, but the synthesis of cage or capsular entities with ion transport properties is often challenging. A variety of molecular building blocks, such as calixarenes or cavitands, has been employed to study encapsulation and ion-transport properties. Recently, we have studied the transport of ions into the interior of gallium-containing pyrogallol[4]arene nanoassemblies, and the results of those studies are the focus of this article. Specifically, the transport of silver(I), cesium(I) and thallium(I) ions into the interior of C-butylpyrogallol[4]arene nanocapsules has been investigated. The transformation of solid-state spherical gallium hexamers to solution-phase toroidal frameworks suggests a structural rearrangement and concomitant inclusion or exclusion of ions in solution. Cation…π interactions and the anion position in the assembly play important roles in the stability of the inclusion complexes.