Self-Assembled Superanions: Ionic Capsules Stabilized by Polynuclear Chromium(III) Aqua Cations

An inclusion complex of an inclusion complex: so can the superanion [{Na+⊂(18-crown-6)(OH2)2}⊂{(p-sulfonatocalix[4]arene4−)2}]7− (illustrated here) be described. These self-assembled ionnic capsules can facilitate the crystallization of polynuclear transition metal aqua ions that have different charge, size and shape, such as [Cr2(OH)2(H2O)8]4+, [Cr3(OH)4(H2O)10]5+ and [Cr4(OH)6(H2O)12]6+.