CALIX[4]ARENES WITH PENDANT AMIDE AND PHOSPHINE OXIDE FUNCTIONALITIES- USE AS EXTRACTIVE AGENTS AND CARRIERS FOR SILVER(I) IONS

The solvent extraction properties towards Ag+ of 6,28-bis(diphenylphos phinoylmethoxy)calix[4]arenes (X = CH2(O)NEt2 (1), CH2P(O)Ph-2 (2), CH 3 (3), CH2C(O)Et (4)) have been studied. Each ligand forms a 1 : 1 com plex with silver(I). Ligand 1, which bears two amide functionalities, is the most efficacious, emphasizing the crucial role played by the po lar amide groups. The rate of transport of AgNO3 through a bulk liquid membrane with this ligand as carrier was shown to be superior to that of DC18C6, a structurally-related multi-oxygen donor carrier. NMR and IR data suggest that Ag+ is coordinated to each of the oxygen atoms i n the ligand leading to an encapsulated structure [Ag subset of 1](+).