Preparation and characterization of preyssler-type phosphotungstic acid, H15-n[P5W30O110Mn +], with different encapsulated cations (M = Na, Ca, Bi, Eu, Y, or Ce), and their thermal stability and acid catalyst properties

Article abstract of DOI:10.1002/zaac.201400038

Preyssler-type phosphotungstic acid, H_15-n[P₅W ₃₀O₁₁₀Mⁿ⁺], with different encapsulated cations (M = Ca²⁺, Bi³⁺, Eu³⁺, Y³⁺, Ce³⁺) were prepared and characterized using ³¹P NMR and IR spectroscopy, acid-base titration, and elemental analyses. The pK_a value of an internal proton of Ca-encapsulated derivative, [P₅W₃₀O₁₁₀CaH_in] ^12-, was estimated to be 5.9. Their thermal stabilities and acid catalyst properties were compared with a parent Na-encapsulated Preyssler-type phoshotungstic acid, H₁₄[P₅W₃₀O ₁₁₀Na]. Thermal stability of the Preyssler-type molecule was increased by exchanging the encapsulated Na⁺ with Bi³⁺, Eu³⁺, or Ce³⁺, with keeping their high acidic properties. Copyright