Halo-derivatised calix[4]tubes

Halo functionalisation of calix4]tubes has been investigated through both derivatisation of individual calix4]arenes and calix4]tubes, using classical synthetic methods, to allow preparation of a series of novel derivatives. The solution and solid state properties are in accordance with the constituent4]arenes adopting flattened cone arrangements which on complexation with potassium simplify to a regular cone. Electrospray and 1H NMR studies, combined with molecular modelling have been used to ascertain the metal binding of this new series of cryptand like ionophores, demonstrating their retained selectivity for binding potassium over other Group 1 metals and the dependence on counter anion in the weak binding of silver.