Exo- and endo-receptors in one. A novel class of supramolecular structures housing transition-metal-binding Bi- and terpyridine units alongside lithium ion-selective trispirotetrahydrofuranyl components

The preparation of bipyridine and terpyridine ligands covalently linked via acetylenic and alkoxy tethers to rigid inositol orthoformate platforms is described. The constitution of compounds 3-6 is such that latent exo- and endo-receptor properties are simultaneously present with specific binding sites for Li+ and transition-metal ions. The 2-fold complexation in different regions is not dependent on prior molecular association. To gauge this unprecedented property, the model systems 11-14 were synthesized and their response to CuCl and FeCl2 probed by UV-vis and MS techniques. In a similar fashion, the ability of 3-6 to ligate lithium ions chemoselectively was evaluated by electrospray methods. The introduction of controlled amounts of both types of cation followed, and conversion to insoluble oligomeric products presumed to result from integral incorporation of the different metal ions in the expected fashion was achieved.