Hydrothermal Synthesis, Crystal Structure, and Catalytic Performance of Four Organic-Inorganic Hybrids Based on Polyoxometalates and O/N-Containing Groups

Four new network organic-inorganic hybrid supramolecular compounds [PW12O40](C2H4N3)(3)center dot 6H(2)O (1), [PMo12O40](C2H4N3)(3)center dot 6H(2)O (2), [H4SiW12O40](8)[C6NO2H4](4)[C6NO2H5](16)[C5NH6](4)center dot 39H(2)O (3) and [H3VW12O40] (C6H6NO2)(2)(CHO2)(2)center dot 4H(2)O (4) composed by keggin type heteropolyanion and O/N-containing organic groups of 1H-1,2,4-Triazole or 2,3-Pyridinedicarboxylic acid have been successfully synthesized by hydrothermally method, and characterized by infrared spectrum (IR), thermogravimetric-differentialthermal analysis (TG-DTA), cyclic voltammetry (CV) and single crystal X-ray diffraction (XRD). Compounds 1-4 exhibit three dimensional supramolecular network via hydrogen bonds and/or pi-pi stacking interactions. These compounds exhibit good thermal stability and catalytic ability. They are active for catalytic oxidation of methanol in a continuous-flow fixed-bed micro-reactor, when the initial concentration of methanol is 2.5 g m(-3) in air and flow rate is 10 mL min(-1), the corresponding elimination rates of methanol are 65% (125 degrees C), 85% (125 degrees C), 94% (150 degrees C), and 80% (125 degrees C), respectively.