High Luminance of Heterolanthanide-Based Molecular Alloys by Phase-Induction Strategy

Reactions in water of lanthanide chlorides with the sodium salt of 4,5-dichlorophthalate (dcpa^2-) lead to two families of isostructural coordination polymers: family F1 that gathers compounds with the general chemical formula [Ln₂(dcpa)₃(H₂O)]_∞ with Ln = La-Gd (except Pm) and family F2 that gathers compounds with general chemical formula [Ln₂(dcpa)₃(H₂O)₅·3H₂O]_∞ with Ln = Tb-Lu plus Y. Heterolanthanide molecular alloys that contain both Eu³⁺ and Tb³⁺ ions have been prepared in both structural families. Their luminescence properties have been studied, especially from the brightness point of view. This study revealed that structural family F1 provides molecular alloys that are much more luminescent than those of structural family F2. Therefore, a phase-induction strategy was followed that allowed the design of some molecular alloys (La/Tb/Eu and La/Dy) that are, to the best of our knowledge, among the most luminescent coordination polymers reported so far. This study opens the way to bright luminescent bar codes as well as to bright white luminescent lanthanide-based coordination polymers.