The Construction And Catalytic Properties Study Of Copper-containing Polyoxometalate-Based Metal-Organic Complexes

Polymetallic oxides（POMs）have a wide variety of compositions and structures with oxygen-atom-rich surfaces that can be designed and modified at will and have excellent multi-electron transfer capabilities providing a wide range of functional materials for catalytic applications.Metal-organic coordination polymers（MOCs）as crystalline porous materials with permanent porosity formed by self-assembly of organic bridging ligands and metal ions with well-defined coordination geometry through coordination bonds are one of the most exciting breakthroughs in modern materials chemistry.With the advantages of large specific surface area,tunable porosity,abundant active centers,and diverse choices of metal nodes and organic linkers,metal-organic complexes are promising for a wide range of applications in multiphase catalysis.The functional POMs units,in the form of inorganic templates attached to metal-organic units through non-covalent bonding interactions,are designed and synthesized as POMs-based metal-organic complex materials,which not only combine the advantages of POMs and metal-organic coordination polymers,but also overcome their respective shortcomings,and enhance the stability and functional diversity of the materials and expand their application scope.In this paper,we combined the advantages of POMs and metal-organic coordination polymers and designed a series of POM-based metal-organic complex materials by self-assembly with Cu^II,a flexible ionic ligand,using POMs as inorganic templates,and investigate their properties.（1）A success was achieved in the construction of two novel isomorphic copper-containing POM-based MOCs(PW₁₂-Cu-pbba and GeW₁₂-Cu-pbba)with Keggin-type polyanions[PW₁₂O₄₀]^3-and[GeW₁₂O₄₀]^4-as the templates combined with ligand H₂pbba and Cu^IIions,respectively.These two novel complexes can effectively catalyze the C-H bond oxidation and olefins epoxidation of benzylic compounds under mild conditions with molecular oxygen as the oxidant and isobutyraldehyde as the coreductant.The catalytic activity of PW₁₂-Cu-pbba is superior to that of GeW₁₂-Cu-pbba.Under optimal conditions,PW₁₂-Cu-pbba catalyzed the oxidation of indene to 1-indanone within 48 h in 81%yield and>99%selectivity.Solving the challenge that most monooxygenation reactions require strict reaction conditions such as high temperature and high pressure when molecular oxygen is used as the oxidant is of great importance to achieve an efficient and green oxidation process.（2）Another novel copper-containing POM-based MOCs(W₁₂-Cu-pbba)was constructed using a hydrothermal method with copper nitrate as the reactant and assembled with the classical Keggin-type polyanion[W₁₂O₄₀]^8-in the presence of H₂pbba.The constructed W₁₂-Cu-pbba was applied to the photocatalytic decomposition of water for hydrogen production.The photocatalytic hydrogen production rate of W₁₂-Cu-pbba was up to 3.069 mmol g^-1 h^-1,which exhibited high activity and provided a strategy for the design of highly active photocatalysts.