Synthesis and Properties of Preyssler-Type Polyoxotungstates Formed by the Interaction Between Polyoxometalate and Lanthanide Metals

POMs modified with lanthanide metals combine the advantages of POMs and lanthanide metals, and show promising properties in the fields of luminescence, magnetism, catalysis, etc. Comparing with the classical Keggin-type POMs, the Preyssler-type POMs with larger size exhibit a rich spatial structure evolution, thereby offering potential for the synthesis of polyoxometalates with excellent properties. In this paper, the Preyssler-type POMs K_12.5Na_1.5[NaP₅W₃₀O₁₁₀] (P₅W₃₀) were selected as the research object, five polyoxometalates KNa{[Tb₄(H₂O)₃₂](NaP₅W₃₀O₁₁₀)}·24H₂O(1), KNa{[Eu₄(H₂O)₃₂](NaP₅W₃₀O₁₁₀)}· ·19H₂O(2), KNa{[La₄(H₂O)₂₄](NaP₅W₃₀O₁₁₀)}·22H₂O(3), KNa{[Gd₄(H₂O)₃₀](NaP₅W₃₀O₁₁₀)}·20H₂O(4), KNa{[Sm₄(H₂O)₂₄](NaP₅W₃₀O₁₁₀)}·21H₂O(5) were designed and synthesized with different lanthanide metals by hydrothermal synthesis method. The effects of pH value, stoichiometric ratio and reaction temperature on the synthesis were summarized. The crystal structures of five polyoxometalates were described, and the coordination environment of lanthanide metals was analyzed. PXRD, infrared spectra, thermogravimetric and fluorescence properties of these compounds were studied.