A highly luminescent Eu(iii) complex based on an electronically isolated aromatic ring system with ultralong lifetime

A luminescent Eu(iii) complex with a large electronically isolated aromatic ring system, Eu(hfa)3(DPPTO)2 (where hfa denotes hexafluoroacetylacetonate and DPPTO denotes 2-diphenylphosphoryltriphenylene), is reported. The light-harvesting efficiency of the Eu(iii) complex was assessed from electronic absorption spectra. Luminescence properties were evaluated from luminescence spectra, excitation spectra, luminescence quantum yields, and luminescence lifetimes. A remarkably brilliant luminescence was observed because of the strong light absorption and the high luminescence quantum yield of the Eu(iii) complex. Density functional theory calculations indicated an electronic separation between the energy-donating large π-conjugated orbital and the energy-accepting Eu(iii) orbital. These findings demonstrate that novel Eu(iii) photophysics can be induced by large electronically isolated aromatic ring systems.