Bis(amidopyridine)-linked calix 4 arenes: a novel type of receptor for dicarboxylic acids

Calix[4]arenes 1 and 2, functionalised on their upper rim with amidopyridine groups, have been synthesised. In the case of 1, a detailed binding study with a range of aliphatic and aromatic dicarboxylic acids has been carried out using H-1 NMR spectroscopy. The binding affinities are largely dependent upon the length of the alkyl spacer group, with the highest binding constant observed for dodecanedioic acid. The X-ray crystal structures of 1 and 2 reveal chain structures formed through intermolecular hydrogen bonds between amidopyridine moieties