Luminescence and crystal-field fitting of two optical isomeric complexes of europium

FT-IR and Raman vibrational spectra and electronic emission spectra have been recorded for enantiomers of europium complexes with DBM: dibenzoylmethanate 1,2, and TTFA: 2-thenoyltrifluoroacetonate 3,4, employing the chiral ligands LSS(+)- and LRR(-)-4,5-pinene bipyridine. Contrary to the previously published X-ray data, where geometrical differences were stated to occur for particular enantiomers, the vibrational (and the emission) spectra of the individual optical isomers of a complex are not distinguishable. Using excitation into the Eu3+ 5D2 multiplet term, the emission intensity is weak from 5D1, whereas a complex structure is observed for the 5D0→7FJ transitions. Features in the vibronic sidebands exhibit similar derived vibrational energies to those observed in the Raman spectra. Fittings of 25 4f6 crystal-field energy levels of 2 and 4 have been attempted with some approximations concerning the local Eu3+ environments. The 5D0 emission lifetimes are monoexponential and are 0.5 (1,2) and 0.9 ms (3,4) at room temperature.