Synthetic receptors for dicarboxylates and diammoniums: templated assembly of functionalized catechols around molybdenum and complexation studies

Abstract

The spontaneous templated formation of receptors by assembling organic fragments around a transition metal core has been extended to catechols bearing thioureas and crown ethers. Symmetrical molybdenum complexes were obtained and characterized, and their suitability for the complexation of dicarboxylates and alkyl diammoniums have been determined. The relative flexibility of the fully assembled receptors is responsible for a low binding selectivity. The association constants of the bis crown ether receptor with diammonium are consistently high, most probably because the dianionic receptors develop additional electrostatic interactions with the diammoniums to produce neutral supramolecular complexes.