Octahedron-shaped three-shell Ln14-substituted polyoxotungstogermanates encapsulating a W4O15 cluster: luminescence and frequency dependent magnetic properties

Abstract

A series of new Ln₁₄-substituted polyoxometalates, H₂₇Na₁₆[(Ln₁₄(H₂O)W₄(OH)O₁₄)(WO₄)₄(GeW₁₀O₃₈)₆]·nH₂O (n ≈ 86) (1-Ln, Ln = Eu, Gd, Tb, Dy, Ho, Er), which contain 14 Ln³⁺ and 6 {α(1,5)-[GeW₁₀O₃₈]¹²⁻} units, has been synthesized in one-pot reactions. As the first 14-Ln-containing polyoxometalates, the octahedron-shaped three-shell structure of the [(Ln₁₄(H₂O)W₄(OH)O₁₄)(WO₄)₄(GeW₁₀O₃₈)₆]⁴³⁻ polyanion is made up of a W₄ tetrahedron, a Ln₁₄W₄ tetrahedron and a Ge₆W₆₀ octahedron. Compound 1-Dy exhibits frequency dependent magnetic properties. Compounds 1-Eu, 1-Tb and 1-Dy exhibit the characteristic emission bands of the Ln³⁺ ion.