Assembly And Photocatalysis Of Optically Functional Polyoxometalate-Based Metal-Organic Frameworks

As a new class of porous crystalline materials, metal organic frameworks ?MOFs? display well-defined molecular structures and tailorable functionalities, which are highly desirable for numerous applications including heterogeneous catalysis, gas storage, and drug delivery. Polyoxometalates ?POMs? represent a large diversity of inorganic building blocks with oxygen-enriched surfaces and unique redox catalytic properties. They are well-known oxidative photocatalysts and solid-acid catalysts for a series of chemical transformations. The incorporation of functional POMs into MOFs as template units or bridging ligands may enhance the structure stability and functional diversity, and provide a promising approach to create synergistic catalysts.This thesis focuses on the design and syntheses of optically functional POM/MOFs and their applications as heterogeneous photocatalysts for the C-C coupling reaction. The main contents are as follows:?1? Two photocatalysts CR-BPY1 and CR-BPY2 have been obtained from the reaction of optically functional [SiW11RuO39?H2O?]5-, Cu2+ cations and 4,4'-bipyridine under hydrothermal conditions ?or layering methods?, and they were used as photocatalysts for oxidative C-C coupling reaction. The direct Cu?-O-Ru? bridges in CR-BPY1 enabled the synergistic interaction between photocatalysis and Cu-catalysis, leading to excellent conversion and size-selectivity for the oxidative coupling C-C bond formation with acetophenones and N-phenyl-tetrahydroisoquinoline.?2? A rigid W₁₀O₃₂/MOF photocatalyst ?DT-BPY? has been synthesized from hydrothermal reaction of optically functional [W₁₀O₃₂]4-, Cu2+ cations and 4,4'-bipyridine and applied for the site-selective C-H alkylation of aliphatic nitriles. The high catalytic efficiency, excellent size-selectivity, high stability and good recyclability of the photocatalyst DT-BPY offers an environmental-friendly route for the application of nitriles in both the laboratory and industry.?3? A breathing W₁₀O₃₂/MOF photocatalyst ?DT-DPDO? has been obtained from the reaction of 4,4'-bipyridine-N,N'-dioxide, optically functional [W₁₀O₃₂]4- and Cu2+ cations via layering methods and was successfully used for the light-driven acceleration of the site-selective C-H activation. The 1D channels of DT-DPDO can encapsulate the reaction substrates via the breathing process which were observed by single-crystal X-ray analyses.