Thermally-transferable fluorescent europium complexes

A donor element for thermal transfer comprising a support having on one side thereof a fluorescent europium complex dispersed in a polymeric binder. In a preferred embodiment, the complex has the formula: wherein: D is a substituted or unsubstituted, aromatic, 5- or 6-membered carbocyclic or heterocyclic moiety; and J is -CF₃, -CH₃, -CH₂F or -CHF₂. In another preferred embodiment, the europium atom may also have attached thereto at least one monodentate ligand with an electron-donating oxygen or nitrogen atom or at least one bidentate ligand with two electron-donating oxygen, nitrogen or sulfur atoms atoms capable of forming a 5- or 6-membered ring with the europium atom.