Synthesis,Properties And Catalysis Of Functional Complexes Based On Tungsten And Molybdenum

Metal-organic frameworks(MOFs)are hybrid solids with infinite networks built from organic bridges and inorganic connecting nodes.MOFs have attracted considerable attention over recent years,because of their intriguing architectures and properties as well as potential applications in heterogeneous catalysis,photo-catalysis and functional materials.Polyoxometalates(POMs)are a large family of well-known polynuclear metal-oxo clusters with intriguing architectures and properties,which displayed potential applications in catalysis because of their thermal stability,redox potentials,(multi)electron-transfer properties,acidities,and photosensitivity.Especially in the photocatalytic oxidation reaction,POMs have irreplaceable excellent performance compared with traditional catalysts.The introduction of POMs into MOFs resulted polyoxometalate-based metal organic frameworks(POMOFs)at the molecular scale will contribute to combine applications in catalysis of POMs and heterogeneous catalysis of MOFs,thus endowing them with and multiple functionalities distinctively different from the POMs or MOFs alone and achieving efficient heterogeneous catalysis.Herein,a series of new MOFs/POMOFs hybrids were constructed by molybdate and tungstate as raw materials,and their applications in heterogeneous catalysis are discussed.The whole paper is divided into two parts:Firstly,synthesis of Mo-incorporated MOFs and explored these species for catalysis of olefin oxidation and CO2 cycloaddition.Secondly,synthesis of Keggin polyoxometalates based metal organic framework(POMOFs)and studied them for photocatalysis in coupling reaction of benzyl amine was studied.In chapter 1,we synthesized three molybdate based functional complexes and the corresponding catalysis was explored according to structural characterizations and properties analysis of them.1)A pure inorganic framework NaCoMo2[Co(?-OH)]O8·H2O(1)was self-assembly prepared under solvothermal conditions by incorporating Mo6+ and Co2+ ions.The catalyst was well characterized by infrared spectroscopy(FTIR),thermogravimetric analysis,nitrogen adsorption-desorption,powder X-ray diffraction(XRD),X-ray crystal diffraction scanning electron spectroscopy(SEM),and X-ray photoelectron spectroscopy(XPS)methods.It displayed high efficiency and selectivity in the photocatalytic oxidation of cyclohexene to 2-cyclohexen-l-of at O2 atmosphere catalyzed by compound 1.The results indicated that compound 1 has excellent cycling stability and capacity to heterogeneous catalysis process.2)By incorporating simple MoO42-,copper(?)ion,and 4,4'-bipyridine(BPY)bridging links in a mixed solution of H2O and CH3CN under hydrothermal conditions,a molybdate-based MOF,[(4,4'-bpy)Cu3(OH)2(MoO4)2](2)was synthesized.The catalyst was well characterized by infrared spectroscopy(FTIR),thermogravimetric analysis,nitrogen adsorption-desorption,powder X-ray diffraction(XRD),X-ray crystal diffraction,scanning electron spectroscopy(SEM),and X-ray photoelectron spectroscopy(XPS)methods,and explored for the assisted tandem catalytic conversion of olefins into value-added cyclic carbonates.The results indicated that compound 2 has excellent cycling stability and capacity to heterogeneous catalysis process and achieved highly efficient for assisted tandem process to synthesize cyclic carbonates from olefins and CO2.3)A new metal-organic framework[(TPT)Co(OH)2(MoO4)4](3),was synthesized by assembling the MoO42-,cobalt ions and 2,4,6-triazine(4-pyridinyl)within a single framework.The catalyst was well characterized by infrared spectroscopy(FTIR),thermogravimetric analysis,powder X-ray diffraction(XRD),X-ray crystal diffraction methods,and explored for the catalytic conversion of epoxides into value-added cyclic carbonates.The results indicated that compound 3 has excellent cycling stability and capacity to heterogeneous catalysis process and achieved highly efficient to synthesize cyclic carbonates from epoxides and CO2.In chapter 2,we designed and synthesized two POMOFs and the corresponding catalysis was explored according to structural characterizations and properties analysis of them.1)In this study,a new hybrid {[Zn(HPYI)3][PW11O39Zn(PYI)]}·3H2O(4)was achieved by assembling zinc cation,L-PYI and keggin-type[PVW11O40]4-as coordination model.The catalyst was well characterized by infrared spectroscopy(FTIR),thermogravimetric analysis,powder X-ray diffraction(XRD),X-ray crystal diffraction,and diffuse reflectance UV-Vis absorption methods,and explored for catalytic conversion of imine from alkenes with benzylamines under visible light with oxygen as oxidant at room temperature.The results indicated that compound 4 has excellent cycling stability and capacity to heterogeneous catalysis process and achieved highly efficient to synthesize imine from alkenes and benzylamines.2)Anew metal-organic polymer[Zn(HPYI)3]2(DPNDI)[BW12O40]2(5),was synthesized by assembling the[BW12O40]5-anion,zinc(?)ion,DPNDI ligands,and L-PYI ligands within a single framework.The catalyst was well characterized by infrared spectroscopy(FTIR),thermogravimetric analysis,powder X-ray diffraction(XRD),X-ray crystal diffraction,and diffuse reflectance UV-Vis absorption and X-ray photoelectron spectroscopy(XPS)methods,and explored for catalytic conversion of imine from benzylamines under visible light with air as oxidant at room temperature.The results indicated that compound 5 has excellent cycling stability and capacity to heterogeneous catalysis process and achieved highly efficient to synthesize imine from benzylamines.