Europium Complexes of a Novel Ethylenedioxythiophene-Derivatized Bis(pyrazolyl)pyridine Ligand Exhibiting Efficient Lanthanide Sensitization

A new class of highly luminescent nine-coordinated europium(III) tris(beta-diketonate) bis[(ethylenedioxythiophene)pyrazolyl]pyridine (L) complexes has been synthesized and the photophysical properties studied: 1 = Eu(hfac)(3)(L); 2 = Eu(tta)(3)(L); 3 = Eu(btfac)(3)(L). The solid-state structure of complex 1 has been determined by single-crystal X-ray crystallography and shows the geometry of the local coordination environment around the Eu(III) ion to be a slightly distorted tricapped trigonal prism. Luminescence lifetimes were found to be 581, 473, and 576 micros for complexes 1-3, respectively. Absolute quantum yields for complexes 1-3 were measured as 16.4 +/- 1.4%, 27.5 +/- 1.2%, and 22.2% +/- 0.3%, respectively.