Potassium selective calix[4]semitubes

Webber, P.R.A., Cowley, A., Drew, M.G.B. and Beer, P.D. (2003) Potassium selective calix[4]semitubes. Chemistry- A European Journal, 9 (11). pp. 2439-2446. ISSN 0947-6539

Abstract/Summary

A new class of ionophore consisting of two calix[4]arene units linked through the lower rim by two ethylene chains, in combination with propyl ether and phenolic functional groups, has been developed. These calix[4]semitube molecules exhibit remarkable selectivity and fast complexation kinetics for potassium over all Group 1 metal cations. Molecular modelling studies, using structural models derived from crystallographic data, suggest the potassium cation is complexed by a horizontal, side-on route and not through the calix[4]arene annulus. The length of the bridging alkylene chain between the respective calix[4]arenes of the semitube structure dictates the strength and selectivity of alkali metal cation binding.