Encapsulation and stabilization of reactive aromatic diazonium ions and the tropylium ion within a supramolecular host

Supramolecular assemblies with internal cavities are being developed as nanoscale reaction vessels to protect or modify the reactivity of guest species through encapsulation. Diazonium cations and the tropylium cation were examined for their ability to encapsulate in the tetrahedral [Ga4L6](12-) supramolecular assembly. The 4-(diethylamino)benzenediazonium cation 1 readily formed a 1:1 host-guest complex with this assembly, and this encapsulation prevented I from re-acting with 2,4-pentanedione in D2O. The tropylium cation also formed a 1:1 host-guest complex with the [Ga4L6](12-) assembly, greatly slowing its decomposition in D2O, Encapsulation in the protected environment of this host cavity alters the reactivity of these guest molecules, giving them greater stability. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).