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Photoluminescent properties of the inclusion compound of β-cyclodextrin and tris(dibenzoylmethane)europium(III) dihydrate, in the solid state, are reported. This compound and the precursor salt, Eu(DBM)3 · 2H2O (DBM=dibenzoylmethane), were characterized by IR spectroscopy, X-ray powder diffraction and differential scanning calorimetry. The emission data indicate that the host-guest interaction (at 77 K) causes an intensification of some bands corresponding to the 5D0→7FJ (J=0–4) transitions associated with one of the site symmetries existing in the guest compound. Based on the luminescence spectrum of the supramolecular compound the Ω λ experimental intensity parameters (λ=2 and 4) were calculated for the electronic transitions 5D0→7F2, 4. The value of the Ω 2 intensity parameter for this new compound is smaller than for the guest, suggesting an effective interaction between the β-cyclodextrin and the closer chemical environment of the Eu3+ ion. On the other hand, the values of the Ω 4 parameter for the inclusion compound are twice larger than the one of the guest, suggesting that the steric effect is more significant in the supramolecular species. Comparison between the luminescence lifetimes of the guest and inclusion compound indicates that the β-cyclodextrin contributes to increase the lifetime of the 5D0 emitting level. The time-resolved spectra of the inclusion compound corroborate the presence of more than one site symmetry occupied by the rare earth ion.

We discuss the syntheses, properties and the luminescence of the complexes, Eu(TTA) 3 · 2L · H 2 O, where TTA = thenoyltrifluoroacetonate, L=15C5 (1,4,7,10-tetraoxa-13-azacyclopentadecane,13-phenyl) and 18C6 (2,3,11,12-dicyclohexano-1,4,7,10,13,16-hexaoxacyclooctadecane). The film complexes with 15C5 and 18C6 ligands contain only one water molecule. The Ω λ experimental intensity parameters ( λ =2 and 4) and the ratio between the intensities of the 5 D 0 → 7 F 0 and 5 D 0 → 7 F 2 transitions ( R 02 ) were obtained for the compounds Eu(TTA) 3 · 2(15C5) · H 2 O ( Ω 2 =39.5 × 10 −20 cm 2 , Ω 4 =8.9 × 10 −20 cm 2 and R 02 =0.0087) and Eu(TTA) 3 · 2(18C6) · H 2 O ( Ω 2 =39.3 × 10 −20 cm 2 , Ω 4 =5.8 × 10 −20 cm 2 and R 02 =0.0098). The macrocyclic compounds, powder form, were also measured. The luminescence spectra of the Eu(TTA) 3 · 2L · H 2 O films give the largest Ω 2 intensity parameter, due to the hypersensitive 5 D 0 → 7 F 2 transition and indicating that the rare earth ion is in a polarizable chemical environment. The lifetimes of the macrocyclics complexes in the powder and film were measured.