Intensive emission of Eu(iii) β-diketonate complexes with arsine oxide ligands

Abstract

The development of luminescent lanthanide complexes hinges significantly on the judicious combination of counter anions and neutral ligands. The hexafluoroacetylacetonate (hfa) anion is a typical example of the counter anions used in this application because its low-vibrational C–F bonds are beneficial in restricting non-radiative deactivation. Recently, arsine oxide has emerged as a promising alternative to phosphine oxide, which is a neutral ligand typically utilized in luminescent lanthanide complexes. However, the use of arsine oxide has been limited to experiments involving europium trinitrate (Eu(NO₃)₃). This study synthesized Eu³⁺ complexes incorporating arsine oxide and hfa ligands, and investigated their photophysical properties. The results demonstrated that the use of the tri(1-naphthyl)arsine oxide ligand led to a highly efficient red emission. Fascinatingly, the Eu³⁺ complex with tri(1-naphthyl)arsine oxide exhibited luminescence even at 500 K, in contrast to other complexes whose luminescence ceased at this elevated temperature.