Synthesis and Photophysical Properties of Eu(III) Complexes with Phosphine Oxide Ligands including Metal Ions

Lanthanide (Ln(3+)) complexes composed of luminescent Eu3+ complex and joint metal blocks (Al3+, Zn2+ and Pd2+ complexes) are reported. The Eu3+ complexes [Eu(hfa)(3)-(dppy)(2)PdCl2](n) (Eu-Pd), [Eu(hfa)(3)(dppy)(2)ZnCl2](n) (Eu-Zn) and [Eu(hfa)(3)(dppy)(4)AlCl3](n) (Eu-Al) (hfa: hexafluoroacetylacetonato, dppy: 4-pyridyldiphenylphosphine oxide) were synthesized by the complexation of [Eu(hfa)(3)(H2O)(2)] with [MCln-(dppy)(m)] (M = Pd2+, Zn2+ and Al3+). These predicted structures were estimated using single-crystal X-ray structural analyses and DFT calculations. Photophysical properties of these complexes were evaluated based on the emission lifetimes and emission quantum yields. The emission quantum yields are dependent on the moiety of the joint metal blocks. Eu-Al complex shows the largest emission quantum yield (Phi(ff) = 72%). In contrast, the emission quantum yield of Eu-Pd is found to be 1.3%. The structures and photophysical properties of Eu3+ complexes linked with joint metal blocks are demonstrated.