Highly Luminescent Homoleptic Europium Chelates

The need for efficient and photostable lanthanide luminescent materials is dramatically increasing, in particular with respect to their growing application in lighting devices and biosciences. To this end, we have developed a facile synthesis of benzimidazole-substituted pyridine-2-carboxylic acids that efficiently sensitize europium luminescence in homoleptic neutral nine-coordinate complexes with overall quantum yields of 56−61% and lifetimes of 2.1−2.6 ms in the solid state at ambient conditions. The complexes reported here are potential synthons for the design of a variety of luminescent materials.