Rapid capture of 4,13-diaza-18-crown-6 molecules by p-sulfonatocalix[4]arene in the presence of trivalent lanthanide ions

Abstract

4,13-Diaza-18-crown-6 in the presence of aquated trivalent lanthanide ions and p-sulfonatocalix[4]arene results in a ‘molecular capsule’ type arrangement with two 4− charge calixarenes and two water molecules shrouding the di-protonated crown ether with overall charged balance from two lanthanide ions. Analogous chemistry in the presence of 1-aza-18-crown-6 under the same conditions results in an unusual bi-layer structural motif devoid of the crown ether, the difference in chemistry being in part ascribed to any ‘molecular capsule’ formed for the mono-aza crown ether taking on an overall 7− charge rather than a 6− charge, requiring fractional lanthanide ions for charge balance.