Three new organic–inorganic hybrids based on Keggin ions and aminopyridine: Crystal structure and catalytic property

Three new organic–inorganic supramolecular hybrids, namely, (2-C5H7N2)4(PMo12O40)2·(2-C5H6N2)6·(C4H8N4)·H2O (compound 1), (3-C5H7N2)6·(PMo12O40)2·(3-C5H6N2)4·H8O4·(H2O)8 (compound 2), (4-C5H7N2)6(PMo12O40)2·(4-C5H6N2)4·(C4H6N3) (compound 3), have been synthesized by hydrothermal method and characterized by elemental analyses, IR, UV–vis, TGA and single-crystal X-ray diffraction. Compound 1–3 constructed from Keggin polyoxoanions and 2-/3-/4-aminopyridine organic ligands, exhibit an extended three-dimensional supramolecular network via hydrogen bonding and π–π stacking interactions, while compound 2 contains a tetramolecular water clusters. compounds 1 and 3 have a higher catalytic activity for the oxidation of acetone tested in a continuous-flow fixed-bed micro-reactor. When the initial concentration of the acetone is 6.1 g m−3 in air and the flow velocity is 4.5 mL min−1, the acetone is completely eliminated at 160 °C. But compound 2 has lower catalytic activity for the oxidation of acetone.

► Three new organic–inorganic supramolecular hybrids based on Keggin polyoxotungstates were synthesized by hydrothermal method.
► The intramolecular and intermolecular hydrogen bonds make compounds form into supramolecular networks.
► Compound 1 and 3 had a high catalytic activity for the oxidation of acetone.
► This work, to some extent, provides some effective strategies in the design and construction of POM based hybrid materials.