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(β-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 EuIII ion to be a slightly distorted tricapped trigonal prism. Luminescence lifetimes were found to be 581, 473, and 576 μs 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.