calixarenes and 4-(2-pyridylazo)resorcinol

Literature reports of the efficacy of para-sulfonatocalix[6]- and calix[8]-arenes as U(vi) complexants indicated that they might be useful for in vivo chelation of the novel therapeutic alpha-emitter (230)U. We have studied the complexation of U(vi) with para-sulfonatocalix[6]arene and para-sulfonatocalix[8]arene by time resolved laser induced fluorescence spectroscopy and using competition methods with Chelex resin and 4-(2-pyridylazo)resorcinol in simplified and in biological media. New thermodynamic parameters describing the stability of U(vi)-para-sulfonatocalix[n]arene [n = 6, 8] complexes were obtained. Although the interactions are strong, the complexes do not exhibit sufficient stability to compete with carbonate ions and serum proteins for complexation of U(vi) under physiological conditions.

Topics: Calixarenes; Chelating Agents; Humans; Hydrogen-Ion Concentration; Resorcinols; Serum Albumin; Uranium