Synthesis, sparkle model and spectroscopic studies of the Eu(hfc) 3·bipyO 2 complex

Abstract

The synthesis and spectroscopic study of the Eu(hfc) 3·2H 2O complex (hfc: 4,4,4-trifluoro-butyryl (+) canfore) with bipyridinedioxide (bipyO 2) is described. The coordination of bipyO 2 to the Eu(III) ion in the complex is evidenced due to the presence of a strong band at 1241 cm −1 shifted from 1252 cm −1 in the bipyO 2 spectrum and attributed to the stretch of its N-oxide group. The complex Eu(hfc) 3·bipyO 2 (hfc: 6,6,7,7,8,8,8-heptafluoro-2,2′-dimethyl 1,3,5-hydroxymethyllene (+) canfore) has a lifetime of 652 μs which is higher than that of the Eu(hfc) 3·2H 2O complex as well as that of the similar complex with β-diketone with CF 3 group. This lifetime value confirms that the Eu(III) luminescence in the complex Eu(hfc) 3·bipyO 2 is stronger than in both complexes above cited. The geometry of this complex has been previously optimized using the sparkle model and the results have been used to perform theoretical predictions of the Judd–Ofelt intensity parameters Ω λ ( λ=2.4) using the simple overlap model (SOM) and correlated to experimental data obtained by means of the emission spectra. The experimental value of the area of the 5D 0→ 7F 2 transition is 20 times larger than that of the 5D 0→ 7F 1 transition. This reflects the hypersensitivity of the 5D 0→ 7F 2 transition. A good agreement between theoretical and experimental UV absorption spectra of the complex has been obtained. This result increased our confidence in the predicted structure.