Preparation Of MOF-magnetic Graphene Functionalized Materials And Enantioselective Separation Of Chiral Drug Intermediates

Metal-organic frameworks?MOFs?,a new type of functional porous materials,which have shown attractive applications,such as gas storage,catalysis,separation and many other fields due to their high specific surface area,rich topologies,stable microporous,availability of modification of pore surface and so on.As another important section of MOFs,chiral MOFs also have attracted much attention in asymmetric catalysis and separation because of their porous functionalities and chirality.As an important precursor for the preparation of graphene?G?,graphene oxide?GO?not only contains a large amount of oxygen-containing groups,such as hydroxyl,epoxies and carboxyl groups,but also shows the characteristics of the layered structure with a large specific surface area.The presence of oxygen-containing groups can improve the hydrophilicity of graphene oxide and provide reaction sites for preparing functionalized graphene oxide materials.MOF-containing nanocomposites,developed by encapsulating GO nanoparticles into MOFs,can integrate the advantages from each component and endow the hybrids with improved synergic effects.To the best of our knowledge,there is no report on the application of graphite oxide-MOF composite in the field of magnetic solid phase extraction and enantioseparation research.In this paper,magnetic graphene oxide functionalized chiral MOFs were prepared and applied to magnetic solid phase extraction to enantioselective capture of chiral drug intermediates.These composites can not only take advantage of large surface area and good dispersion of graphene oxide,but also have the porosity and chirality of chiral MOFs,They combine the magnetic properties of magnetic materials and have a wide range of application prospects.The main contents are as follows:First,magnetic Fe₃O₄ was prepared by hydrothermal method,and silica was coated on the surface of magnetic Fe₃O₄ nanoparticles by sol-gel method.Then,3-aminopropyltriethoxysilane?APTES?was used to functionalize Fe₃O₄@SiO₂ and the Fe₃O₄@SiO₂-NH₂ was obtained.Fe₃O₄@SiO₂-NH₂-GO?referred to MGO?was prepared by chemical bonding of Fe₃O₄@SiO₂-NH₂ and GO.The MGO materials were characterized by the scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,infrared spectrum?IR?and X-ray powder diffraction?XRD?.Second,MOF1,[Zn2?bdc??L-lac??dmf?]?bdc=terephthalic acid;L-lac=L-lactic acid?was prepared under normal pressure,and then different doping amount of MGO were added into MOF1 to abtain Fe₃O₄@SiO₂-NH₂-GO@MOF1?referred to MGO-ZnBLD?,which were characterized by the scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,infrared spectrum?IR?,Thermogravimetric analysis?TGA?,hysteresis loop?VSM?,X-ray powder diffraction?XRD?and N itrogen adsorption.The experimental results showed that,when the doping amount of MGO was 5%,enantiomeric excess?ee?value of selective adsorption of methyl phenyl sulfoxide with magnetic solid phase extraction was up to 90.9%.The whole process can be completed within 2 minutes,and the composites can be reused for at least seven times without any apparent loss of performance.Third,MOF2,[Zn2?D-Cam?2?4,4'-bpy?]n?D-Cam=D-camphorate;4,4'-bpy =4,4'-bipyridine?was also prepared under normal pressure,by adding different amount of MGO into MOF2 to abtain the Fe₃O₄@SiO₂-NH₂-GO@MOF2?referred to MGO-ZnC B?,which were also characterized by the scanning electron microscopy,transmission electron microscopy,infrared spectrum,Thermogravimetric analysis,hysteresis loop,X-ray powder diffraction,N itrogen adsorption and EDS analysis.The experimental results showed that,when the doping amount of MGO was 10%,enantiomeric excess?ee?value of selective adsorption of 1,1'-bi-2-naphthol with magnetic solid phase extraction was up to 74.8%.The whole process can be completed within 3 minutes,and the composites can be reused for at least seven times without any apparent loss of performance.Fourth,by using the Fe₃O₄@SiO₂-NH₂-GO@MOF2?referred to MGO-ZnCB?to enantioselective capture of another chiral substance named 2,2'-furoin,we can find that when the doping amount of MGO was 8%,enantiomeric excess?ee?value of 2,2'-furoin was 57.4%,the whole process can be completed within 2 minutes,and the composites can be reused for at least seven times without any apparent loss of performance.