Investigation Of The Assembly And Properties Of Polyoxometalates Modified By Nitrogen Oxide Ligands And Rare Earth Metals

In this paper, three new inorganic-organic hybrid compounds based onpolyoxometalate building blocks have been synthesized under aqueous synthesisor hydrothermal technique, and structurally characterized by elemental analyses,IR, TG, XPRD and single crystal X-ray diffractions. The magnetic properties andelectrochemical properties of these compounds have been studied.Under aqueous synthesis condition by using （NH₄）6[H₂W₁₂O₄₀]·3H₂O clusterwith sufficient charge density, dpdo ligand and Ce（NO₃）₃/Nd（NO₃）₃rare-earthsalt as the reaction material, two compounds based on polyoxometalate havebeen synthesized and characterized:[Hdpdo]Ce（Hdpdo）₂（H₂O）6[H₂W₁₂O₄₀]·17H₂O、[Hdpdo]Nd（Hdpdo）₂（H₂O）6[H₂W₁₂O₄₀]·18H₂O （dpdo=4,4’-dipyridine-N,N’-dioxide）, Single-crystal X-raydiffraction analysis reveals that two compounds are isostructural, showing anovel3D interdigitated architecture, In addition, taking the former compound asan example, the electrochemical property has been studied and shown a goodelectrocatalytic reactions toward the reduction of hydrogen peroxide （H₂O2）.In fact, it is difcult to synthesis the POM-based d–f heterometalliccompounds with the one-pot procedure owing to the strong competitive reactionbetween the d and f metals, and usually form the POM-based compounds bysingle d or f metal, In order to overcome the synthetic drawbacks, a novel3d–4fheterometallic POM-based compound has been synthesized firstly via usingstepwise method. Na₂[Ce₄（H₂O）₂₂（dpdo）₅](Mn₂HP₂W₁₅O₅₆)₂·8H₂O,Meanwhile, its magnetic and electrocatalytic properties has been investigated.Notable, the electrochemical studies have shown that this compound hasbifunctional electrocatalytic activities towards not only reduction of normalinorganic molecules iodated, but also oxidation of biologic molecules ascorbic acid and dopamine.