Syntheses,Characterizations And Visible-light Photocatalytic Properties Of Novel Metal-organic Frameworks

Metal organic frameworks?MOFs?,as well as metal organic coordination polymers?CPs?,are a class of new functional crystalline materials.MOFs exhibit well performance in the research and application of various fields such as chemistry,biology,environmental science and medicine with the advantages of structural diversity,various physical and chemical properties.Such as permanent porosity,tunability of size,large void volume,specific surface area and variability of frameworks.Aiming at designing and preparing novel structural MOFs and exploring the catalytic performance of such materials,many coordination polymer catalysts have been successfully synthesized and exhibited good catalytic properties.Studying the novel structure of MOFs and exploring their potential applications as the starting point.Two kinds of structurally different Zn-CPs were successfully prepared combining the visible-responsive ligand ADBEB with metal Zn by controlling solvent effect,auxiliary ligand and reaction temperature.The studies of single crystal diffraction and X-ray diffraction,infrared,ultraviolet and thermal were used to discuss structural features and physicochemical properties of the two Zn-CPs.And subsequently studied of synthetic MOFs as photocatalysts to induce organic compounds conversion.The main work is summarized as follows:1.A stable 2D layered coordination polymer 1,with molecular formula of Zn?ADBEB??DMA?,was constructed by using dicarboxylic acid ligands ADBEB containing anthracene groups and Zn?NO3?2.Single crystal structure analysis shows that 1 was closely stacked in an ABCD fashion,each single-layer has an infinite long-range stacking interaction with a face to face distance about 3.60?.In addition,the benzoic acid groups at the ends of the ADBEB ligand,which should be in a planar configuration,are deflected to varying degrees from the central anthracene functional group.Due to the conjugated ligand ADBEB has good visible light absorption properties,the visible light absorption spectrum of the synthesized 1 exhibits a red shift phenomenon with the absorption edge at 550 nm.We explored the photocatalytic properties for triggering the transformation of sulfides to sulfoxide under visible light irradiation with 1 as a photosensitizer.It was found that 1exhibited an efficient photoactivity during the oxidation process with excellent conversion and chemoselectivity in the mixed solvent system.The quenching experimental and electron paramagnetic resonance?EPR?spectroscopy confirmed that the single oxygen ¹O₂ induced by energy transfer process of the photoexcited coordination polymer in this photocatalytic system is the reactive oxygen species.2.A novel 3D"pillared-layer"coordination polymer 2?[Zn₂?ADBEB?₂?bpy?]·2DMF?was prepared by mixing 4,4'-bpy as an auxiliary ligand with the above-mentioned ions and ligands materials by the"mixed-linker"synthesis method,in which a"carboxylic acid-metal"2D network units formed by Zn²⁺and the ADBEB ligand,and then the"pillar-ligand"bpy supported the layers to build the 3D microporous frameworks.2 also exhibited good visible light absorption properties and was explored to promote the coupling of benzylamine oxidation as the photocatalyst under the oxygen atmosphere.It exhibited high conversion and chemoselectivity in both single and mixed solvents.It was speculated by active oxygen species quenching experiments that ¹O₂ produced by energy transfer was the main active oxygen species.