Synthesis and crystal structures of supramolecular compounds of polynuclear aluminum(III) aqua hydroxo complexes with cucurbit[6]uril

Abstract

Supramolecular compounds of the di-, trideca-, and triacontanuclear aluminum aqua hydroxo complexes, viz., [Al2(OH)2(H2O)8]4+, [Al12(AlO4)(OH)24(H2O)12]7+, and [Al30O8(OH)56(H2O)26]18+, respectively, with the organic macrocyclic cavitand cucurbit[6]uril (C36H36N24O12) were prepared by evaporation of aqueous solutions of aluminum nitrate and cucurbit[6]uril after the addition of pyridine, ammonia, KOH, or NaOH at pH 3.1–3.8. X-ray diffraction study demonstrated that the aqua hydroxo complexes are linked to the macrocycle through hydrogen bonds between the hydroxo and aqua ligands of the polycations and the portal oxygen atoms of cucurbit[6]uril.