Luminescence enhancement of the Tb(III) ion with the thenoyltrifluoroacetonate ligand acting as an efficient sensitizer

The synthesis, structural investigation, and photophysical properties of the complex [Tb(TTA)2(NO3)(TPPO)2] are reported. Unlike the analog tris-diketonate complex [Tb(TTA)3(TPPO)2], the new complex presents abnormally high luminescence intensity centered on the terbium ion. Our results clearly suggest a higher energy transfer efficiency from the TTA antenna ligand to the Tb(III) ion in the bis-diketonate complex compared with that in the tris-diketonate complex. A mechanism involving the increasing of triplet state energy when one TTA ligand is replaced by the NO3− group in the first coordination sphere is suggested and experimentally investigated to explain the anomalous luminescence properties of the new complex [Tb(TTA)2(NO3)(TPPO)2].