Self-assembled superanions: Ionic capsules stabilized by polynuclear chromium(III) aqua cations

Alexander Drljaca, Michaele J. Hardie, Colin L. Raston, Leone Spiccia

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84 Citations (Scopus)


Aqueous solutions of sodium p-sulfonatocalix[4]arene and 18-crown-6 containing purified, polynuclear hydrolytic CrIII cations [Cr2(OH)2(H2O)8]4+, [Cr3(OH)4(H2O)10]5+ or [Cr4(OH)6-(H2O)12]6+ (as their perchlorates) at about pH 2 afford crystalline, extensively hydrated complexes. These complexes contain the CrIII complex cations and self-assembled globularlike superanions or ionic capsules [{Na+ ⊂ (18-crown-6)-(OH2)2} ⊂ {(p-sulfonatocalix[4]arene4-)2}]7-, which are triply, doubly or singly protonated, respectively. The superanions possess a central sodium ion bound by a crown ether and two trans water molecules; this moiety is further shrouded by two calixarenes. The di-and trinuclear cations can be leached from the solid complexes by treatment with aqueous HClO4, and the complex containing the tetranuclear species is selectively formed from a solution containing a mixture of the various polynuclear cations.

Original languageEnglish
Pages (from-to)2295-2299
Number of pages5
JournalChemistry - A European Journal
Issue number8
Publication statusPublished - 1 Jan 1999
Externally publishedYes


  • Calixarenes
  • Chromium
  • Ionic capsules
  • Polynuclear cations
  • Self-assembly
  • Supramolecular chemistry


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