Synthesis,Properties,Catalytic Of Chiral Polyoxometalate Based Framework

Chiral metal-organic frameworks(MOFs),built from multidentate organic or inorganic ligands,chiral organocatalysts and metal ions,are a class of crystalline materials with infinite network structures.Due to the ability of highly porosity,great stability and tunability,MOFs have attracted much attention for their unique applications in asymmetric catalysis and construct function-oriented materials.Polyoxometalates(POMs)have received growing attention recently due to their excellent thermal and oxidative stability for various purposes and their advantages as green catalysts in olefin epoxidation which other traditional catalysts don't have.By incorporating the oxidation catalyst POMs into one single chiral framework,homochiral POM-based metal-organic frameworks(POMOFs)could be feasibly constructed via self-assembly,which not only take the tremendous advantage of unique redox properties of POM,but also utilize the chirality of PYI to achieve the asymmetric heterogeneous catalysis.,providing a promising way to combine the organic and inorganic catalytic components synergistically.This thesis mainly concerns on the design,preparation and properity studies on the catalytic applications of MOFs with 4'4-bpy,NDPI and H3BTB as bridging ligand.By incorporating the oxidation catalyst POMs,metal ions,the chiral organocatalyst and different size of bridging ligand into one single framework,homochiral POMOFs platforms with asymmetric oxidation catalytic function will be obtained.Compounds 1-10 have been characterized by elemental analysis,FT-IR spectroscopy,TG analysis,UV-vis spectroscopy,X-ray powder diffraction and single-crystal X-ray diffraction studies.In order to realize the substrate molecule high selective recognition and geometric position limit in the POMOFs provided special space limitation,and complete asymmetric epoxy chemical reaction of specific electron-deficient olefin,the most important issue is to match stereo,electronic effect between "chiral ligands-POM-substrate" by checking the impact of MOFs with different geometric configurations,catalytic activity site layouts and space orientations on the catalytic reaction.The main contents are as follows:1)By incorporating a Keggin-type[BW12O40]6-anion and an chiral organocatalytic ligand,PYI,within one single MOF which constructed via 4'4-bpy and Co2+.The chiral enantiomers named Co-PYI1 and Co-PYI2 with 1D structure and the chiral enantiomers named Co-PYI3,Co-PYI4 as well as Co-BPY5 which without chiral.At the same time,above-mentioned compounds have been characterized by elemental analysis,FT-IR spectroscopy,TG analysis,circular dichroism spectra,X-ray powder diffraction and single-crystal X-ray diffraction studies.Then,the catalytic of compounds 1-5 on olefin hydroxylation were studied.The results show that all the compounds 1-4 have great catalytic activity and enantioselectivity in the catalytic hydroxylation of olefins which possess high conversion rate.Meanwile,compounds 1-5 permit catalyst separation and reuse.2)By incorporating naphthalene imide as bridging ligand,prolyl derivatives(L and D-BCIP)as chiral ligand,four chiral polyoxometalates named Co-NDPI-PYI 1(6),Co-NDPI-PYI2(7),Co-NDPI(8)and BW12-NDPI(9)have been synthesized constructed from Keggin type polyoxoanions[BW12O40]5.The compounds of 6-9 have been characterized by elemental analysis,FT-IR spectroscopy,UV-vis spectroscopy,fluorescence spectrum,TG analysis,X-ray powder diffraction,single-crystal X-ray diffraction and Electrochemical properties studies.Then,the photocatalysis of compounds 6-9 on olefin hydroxylation were studied.The results show that the compounds 6-7 have great catalytic activity and enantioselectivity in the catalytic hydroxylation of olefins and the compounds 8-9 have a great catalytic activity.Meanwile,compounds 6-9 permit catalyst separation and reuse.3)By using hydrothermal synthesis,incorporating multidentate ligand H3BTB as bridging ligand,L-pyrrolidine-2-yl-imidazole(L-PYI)as chiral with Mn2+,we have been synthesized a structure of a novel chiral metal-organic framework,Mn-BTB,which with large pores were synthesized.This compound has been characterized by elemental analysis,FT-IR spectroscopy,circular dichroism spectra,TG analysis,X-ray powder diffraction,single-crystal X-ray diffraction studies.At the same time,the adsorption of MB?MO and RhB on catalyst Mn-BTB under different conditions was studied.The results show that the catalyst has great adsorption ability on MB dyes.The Mn-BTB permits catalyst separation and reuse.