Complexing properties of pyrenyl-appended calix[4]arenes towards lanthanides and transition metal cations

Abstract

The binding properties of pyrenyl-appended calix[4]arenes 2-4 towards lanthanide and transition metal cations were investigated by spectrophotometric data processing, which indicated that 2 forms mononuclear species with all the cations studied. The extraction power decreased toward ligands 2-3 except Co2+, then increased for ligand 4, which reflect the better ability of ligands 2 and 4 to complex and extract at the interface. Derivative 3 formed mono and binuclear species simultaneously with the trivalent cations from La3+ to Er3+ but only M2L species with Yb3+. In the case of 4, only M3L was detected for Yb3+ and only ML for La3+, with the complexation of the other cations tending to form mono-, bi- and tri-nuclear species.