Tailoring molecular assemblies for metal ion binding

An investigation of a subtle, but potentially important, effect in metal co ordination chemistry concerned with the spontaneous formation of host-guest assemblies between organic moieties which are themselves potential metal-i on ligands is reported. The use of a ligand 'package' of this type for meta l complexation (where the package exists in solution in equilibrium with it s corresponding metal complex) is potentially a contributing factor to enha nced complex stability. Initially, nmr titration studies were carried out on host-guest systems for med between carboxylic acids and both open chain and macrocyclic amine-cont aining ligands. The stoichiometries of the resulting adducts formed in deut erated methanol or chloroform were determined and in some instances it has proved possible to determine the corresponding step-wise binding constants.