Construction of a Hybrid Family Based on Lanthanide-Organic Framework Hosts and Polyoxometalate Guests

A series of 3D polyoxometalate (POM) based coordination polymers, namely, Ln(4)(pdc)(4)[SiW12O40]center dot xH(2)O (Ln = Eu, Gd, Tb, Dy; x = 19, 13, 14, 18; H(2)pdc = pyridine-2,6-dicarboxylate), have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses (TGA), XRD, and single-crystal X-ray diffraction analyses. Single-crystal X-ray diffraction reveals that they are all isostructural, and the Keggin polyanions [SiW12O40](4-) are wrapped as noncoordinating guests in the nonlinear channels of the 3D host framework with 4(3)center dot 6(2)center dot 8 topology that is formed by rare-earth metal ions and organic ligands. Furthermore, cyclic voltammetry (CV), ethanol-sorption properties, and catalytic properties are also discussed.