Spectral-Luminescent Properties of Mixed-Ligand Europium(III) Complexes with p-Methylbenzoic Acid

Abstract

The spectral-luminescent properties of europium(III) complexes with p-methylbenzoic acid and nitrogen- and phosphorus-containing neutral ligands of compositions [Eu(p-MBA)₃ · D]₂ · xH₂O and [Eu(p‑MBA)₃ · 2H₂O]_n, where p-MBA is the anion of p-methylbenzoic acid and D is 1,10-phenanthroline (phen), 2,2' dipyridyl (dipy), triphenylphosphine oxide (tppo) (х = 0), hexamethylphosphortriamide (hmpa) (x = 1), or benzotriazole (bt) (x = 2) are studied. The electronic absorption spectra, the luminescence excitation spectra, and the Stark structure of ⁵D₀−⁷F_j ( j = 0–2) electronic transitions in low-temperature luminescence spectra of complex europium(III) p-methylbenzoates are analyzed. It is found that the excitation energy transfer to europium ions occurs from the levels of both p-methylbenzoic acid and neutral ligands.