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

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 Co 2+ , 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 La 3+ to Er 3+ but only M 2 L species with Yb 3+ . In the case of 4 , only M 3 L was detected for Yb 3+ and only ML for La 3+ , with the complexation of the other cations tending to form mono-, bi- and tri-nuclear species.