Luminescent Europium(III) Coordination Zippers Linked with Thiophene-Based Bridges

Novel Eu-III coordination polymers [Eu(hfa)(3)(dpt)](n)(dpt: 2,5-bis(diphenylphosphoryl)thiophene) and [Eu(hfa)(3)(dpedot)](n) (dpedot: 2,5-bis(diphenylphosphoryl)ethylenedioxythiophene) with hydrogen-bonded zipper structures are reported. The coordination polymers are composed of Eu-III ions, hexafluoroacetylacetonato ligands, and thiophene-based phosphine oxide bridges. The zig-zag orientation of single polymer chains induced the formation of densely packed coordination structures with multiple intermolecular interactions, resulting in thermal stability above 300 degrees C. They exhibit a high intrinsic emission quantum yield (ca. 80%) due to their asymmetrical and low-vibrational coordination structures around Eu-III ions. Furthermore, the characteristic alternative orientation of substituents also contributes to the dramatically high ligand-to-metal energy transfer efficiencies of up to 80% in the solid state.