Preparation And Properties Of Porous Metal Organic Skeleton Hybrid Materials With Multi - Metal Oxygen Cluster

Polyoxometalates (POMs), acting as a rich class of inorganic metal-oxide cluster compounds with unrivaled structural features and multifunctionality, have attracted long-lasting interest in different areas of catalysis, medicinal chemistry and materials science. Metal-organic Frameworks (MOFs) with adjustable pore size and shape have potential applications in the domains of adsorption and separation processes, drug delivery and magnetism. POM-based MOF materials, which combine the advantages of both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades.In this work, by using the four-zinc capped ε-Keggin anions and rigid carboxylic ligand of H3BTB (1,3,5-tris(4-carboxyphenyl)-benzene) and 5-MIP (5-methylisophthalic acid), we successuflly synthesized two novel POM-based MOF compounds (1-2), which were characterized by single crystal X-ray diffraction, UV-vis, IR, TG-MS and powder X-ray diffraction. Brunauer-Emmett-Teller (BET) surface area was established by N2 adsorption isotherm at 77 K. The electrochemical and electrocatalytic were investigated by using the carbon-pasted electrode (CPE). Following are the details:1. By using a triangular rigid ligand (H3BTB), we obtained an unexpected 2-fold interpenetrated 3D network based on a reduced{ε-H3PMoV8MoVI4O40Zn4}2 dimer, [TBA]6[H3PMoV8MoVI4O40]2[Zn8(BTB)] (1) under hydrothermal condition. Such interpenetrated framework maintains microporous properties in the ab plane and be plane with the channel dimensions of 8 A×8 A and 15 A×10 A, respectively, if omitting the TBA and water molecules inside the channels. Moverover, compound 1 is stable under pH 1-10. The CPE-1 exhibits substantial catalytic activity towards bromate reduction.2. By using a bridging ligand of 5-MIP, a novel 2D network of [TBA]3[H4PMoV8MoVI4O40Zn4][C7H6(COO)2]2 (2) was constructed. CPE-2 also shows remarkable electrocatalytic activity towards bromate reduction.3. A series of crystalline compounds were constructed according to the literatures:(1) [Cu2(BTC)4/3(H2O)2]6[HPW12O40]·(C4H12N)2-25H2O, named as PWCuBTC;(2) [Cu2(BTC)4/3(H2O)2]6[HPMo12O40]·C4H12N)2-20H2O, named as PMoCuBTC;(3) [Cu3(TMA)2(H2O)3]n, named as HKUST;(4) Cr3F(H2O)2O[(O2C)-C6H4-(CO2)]3·nH2O, named as MIL-101.The reduction of p-Nitrophenol (p-Nph) to p-Aminophenol (p-Aph) by an excess amount of NaBH4 was chosen as a probe reaction to evaluate the catalytic activity of above mentioned four composites. The cycled measurement was also investigated. Because Phosphotungstic acid and phosphomolybdic acid are the classic catalysts in industry and they are the raw materials for synthetic PWCuBTC and PMoCuBTC, respectively, the catalytic activity of these two classic POMs were also investigated for comparison. The obtained results show that POMOF have good catalytic effect and good recyclability.