Visible and near-infrared light emitting calix[4]arene-based ternary lanthanide complexes

In this article ternary lanthanide complexes consisting of a calix[4]arene unit and dibenzoylmethane (dbm) as the antenna are described. In the europium complex [(Eu)2]NO3 two solvent molecules are still coordinated to the ion, making substitution of them by the dbm antenna possible. In the ternary complex of europium, an energy back-transfer process plays an important role. The photophysical properties of complexes of three near-infrared emitting lanthanide(III) ions were determined, i.e. ytterbium, neodymium, and erbium. These exhibit dbm-sensitized emission, with luminescent lifetimes comparable to those in other organic ligand systems.