Inorganic-organic hybrids of stannic-containing polyoxometalate and 2-aminopyridine: synthesis, characterization, and catalytic applications

A new inorganic-organic hybrid of 2-aminopyridine/[P2W18O68(HOSnIVOH)3]12- (1) has been synthesized via an aqueous solution reaction of [P2W18O68(HOSnIVOH)3]12- (P2W18Sn3) and 2-aminopyridine. The inorganic-organic hybrid has been characterized using elemental analysis, FE-SEM, EDX, TG analysis, FT-IR, powder X-ray diffraction, and single-crystal X-ray crystallography. The results show that the sandwich structure of P2W18Sn3 polyoxometalate remains intact in the inorganic-organic hybrid but a structure rearrangement of the nanoparticle composed of the Keggin structure (1a) was observed by calcination at higher than 300 degrees C. The single crystal analysis confirms the anchoring of 2-aminopyridine on the P2W18Sn3 polyanion via the formation of a Sn-O-C bond. The catalytic activity of 1 has been evaluated through the oxidation of sulfides to sulfone with H2O2 and that of (1a) in the synthesis of tetrazoles in water and mild reaction conditions.