“Gating” the Pores of a Metal Oxide Based Capsule: After Initial Cation Uptake Subsequent Cations Are Found Hydrated and Supramolecularly Fixed above the Pores

Artificial cells: A polyoxomolybdate capsule, in which the cavity is linked to surface pores by channels, can take up Pr3+ ions. Each uptake reduces the negative charge on the capsule so that eventually no more Pr3+ ions enter the capsule, instead they remain bound on the surface (see structure: external hydrated Pr3+ green polyhedra, encapsulated Pr3+ light green, Mo blue, O red, SO42− yellow). This process models voltage gating of the ion channels of cells.