Synthesis, characterization and photoluminescent properties of europium(III) complexes with ligands bearing benzimidazole groups

Europium(III) complexes have attracted tremendous interests from scientists for their excellent properties and their important potential applications in the fields of organic light emitting diodes, biological labeling, laser media. In this paper, two novel europium(III) complexes having 2-thenoyltrifluoroacetylacetone (tta) as the first ligand and the second ligands bearing benzimidazole groups were synthesized and characterized by FT-IR, UV–Vis, ¹H-NMR, and elemental analysis. The photoluminescent properties of complexes in the solid state, in ethanol solution and embedded in poly(methyl methacrylate) (PMMA) were investigated. All europium(III) complexes exhibited strong luminescent intensity, high quantum yields (Φ) and long luminescent lifetimes. The intrinsic luminescent quantum yields (Φ_LN) and the stimulated emission cross-section (σ_p) of complexes were obtained based on the emission spectra and luminescent lifetimes of ⁵D₀ excited state for europium(III) ion. All europium(III) complexes exhibited relatively high intrinsic luminescent quantum yields. In view of σ_p values, which are the same order as the values of Nd-glass laser for practical use, these europium(III) complexes may find potential applications in the field of high-power laser media.