Assembly of Lanthanide-Containing Polyoxotantalate Clusters with Efficient Photoluminescence Properties

Eight novel lanthanide-containing polyoxotantalates, Cs₃[Ln(H₂O)₆{H₄(TaO₂)₆As₄O₂₄}]·7H₂O (Ln = Sm (1), Eu (2), Tb (3), Dy (4), Er (5), Tm (6), Yb (7), Lu (8)), have been obtained via a one-pot reaction methodology. Each of these compounds is made up of the new type polyanion [(TaO₂)₆As₄O₂₄]^10- with Ln³⁺ linkers, giving a one-dimensional chain. The compounds represent the first family of "pure" Ta-based polyoxometalate lanthanide derivatives. These architectures were characterized by various physicochemical analyses. Furthermore, the photoluminescence properties of compounds 2-Eu and 8-Lu were also explored, and meanwhile time-resolved emission spectroscopy indicated that the {As₄Ta₆} segment makes a contribution to the energy transfer of compound 2 from the polyoxotantalate to the Eu^III center, which efficiently facilitates emissions of the Eu³⁺ center.