Synthesis And Catalysis Of Polyoxometalates/Poly(amidoamine)Dendrimer Composites

Catalysis of polyoxometalates (POMs) continues to attract significant attention dueto their acid-base and redox properties. However, it is difficult to. separate them from thereaction systems. Therefore, dispersing POMs on appropriate supports will be offundamental and practical significance.In this paper, three novel inorganic/organic composites contracted from transitionmetal substituted POMs and poly(amidoamine) (PAMAM) dendrimers,Na₅PW₁₁CoO₃₉/PAMAM, Na₅PW₁₁CuO₃₉/PAMAM and Na₅PW₁₁ZnO₃₉/PAMAM wereprepared by covalent assembly. Retention of the structure integrity of the starting POMsin the as-synthesized composites was confirmed by FT-IR, DR-UV-Vis, XPS, XRD.Dative bonds were existed between POMs molecules and PAMAM dendrimers.Compared with starting POMs, thermo-stability of the composites has been improved inthe different extents.The catalytic activity of Na₅PW₁₁CoO₃₉/PAMAM, Na₅PW₁₁CuO₃₉/PAMAM andNa₅PW₁₁ZnO₃₉/PAMAM were evaluated by oxidation of isobutyraldehyde (IBA) toisobutyric acid (IBAc), electroreduction of H₂O₂ and NaNO₂, and photodegradation ofRhodamineB (RhB), respectively. The results showed that the composites had lesssolubility and higher catalytic activity. Although PAMAM did not display any catalyticactivity, it made the active sites be more accessible for substrate molecules and reagents.Moreover, the catalysts could be recoverable and reusable.