Synthesis and Characterization of Dinuclear Europium Complexes Showing Pure Red Electroluminescence

Two dinuclear Eu III complexes have been synthesized by employing β‐diketones and 2,2′‐bipyrimidine (bpm) as sensitizing ligands for the Eu ion and a bridging ligand, respectively, and characterized by various means including single‐crystal X‐ray crystallography. The use of dibenzoylmethane (dbm) and trifluorothenoylacetone (tta) as β‐diketones gave [Eu 2 (dbm) 6 (bpm)] ( 1 ) and [Eu 2 (tta) 6 (bpm)] ( 2 ). Both show strong intermolecular π–π interactions that may be responsible for their high melting points. The analysis of the absorption, excitation, and emission spectra of the dinuclear complexes along with a comparison with analogous mononuclear complexes containing the same β‐diketone ligands and 1,10‐phenanthroline (phen) suggests that the dinuclear complexes follow the luminescence mechanism of general Ln III complexes. An EL device with the structure ITO/PEDOT/PVK + PBD + 1 10 wt.‐%/LiF/Al shows pure red emission with an efficiency similar to those of mononuclear complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)