Design,Synthesis And Catalytic Performance Of Covalently Linked Porous Organic Polymer Frameworks

Porous organic polymers linked by covalent bond mainly include crystalline covalentorganic frameeorks（COFs）and non-crystalline porous organic polymers.Different kinds of non-crystalline porous organic polymers are further classified as : Hyper-Crosslinked Polymers;Polymers of Intrinsic Microporosity and Conjugated Microporous Polymers.Porous organic polymers materials have been used in many fields by integrating different molecular functional components due to their large specific surface area,light weight,excellent stability and easy functionalization at the molecular level such as in gas storage/separation,photovoltaics,sensoring,and heterogeneous catalysis.The presetting of structure and the flexible adjustment of function,especially the porous organic materials with catalytic activity,have attracted extensive research in the field of organic transformation and photocatalysis.The design and synthesis of various porous organic polymer materials were used by different functional monomers and based on different synthesis methods.These polymer materials were characterized by Fourier transform infrared（FT-IR）spectroscopy,solid state 13 C cross-polarization/magic-anglespinning（CP/MAS）NMR spectroscopy,elemental analyses,Scanning electron microscopy,Transmission electron microscopy,nitrogen sorption isotherms analysis and so on.Moreover,their applications in organic transformation,photocatalytic organic transformation and other fields were also discussed.The main conclusions of this thesis mainly include the following five parts:Visible-light-driven organic transformation has attracted a great attention owing to the environmental friendship of visible light and mild reaction conditions recently.From the viewpoint of practical application,up to now,the efficient,recyclable,metal-free and cost-efficient heterogeneous photocatalysts based on POPs by facile preparation processes have rarely been explored.In the chapter two,we have synthesized a porous organic polymer（CF-HCP）through the one-pot Friedel-Crafts alkylation of 2,7-bis-（Ncarbazolyl）-9-fluorenone（CF）using a formaldehyde dimethyl acetal（FDA）as crosslinker in the presence of anhydrous Fe Cl₃.The CF-HCP could be used as a low-cost,metalfree heterogeneous photocatalyst in organo-photocatalyst transformation including the oxidative coupling of primary amines,aerobic dehydrogenation of secondary amine substrates and selective oxidation of sulfide under visible-light irradiation due to the properties of high surface area,large pore volume,hierarchical porosity,superior stability and excellent absorption under the visible region.CF-HCP photocatalyst can be recycled for multiruns without obvious decreasing in catalytic efficiency.An excellent yield was also afforded in the scaled-up reaction.In addition,the mechanism of the photooxidative coupling reaction of amine by CF-HCP was also studied in detail.In particular,the most remarkable feature for 2D-COFs is periodic columnar π-arrays arise from layered stacking of 2D polymer sheets.The ordered columns are ideal channels for exciton diffusion,migration and separation,and 2D-COFs have proven as a powerful platform for designing functional materials in optoelectronic devices.However,the field of 2D-COFs as heterogeneous photocatalysts for organic transformations remains largely untrapped up to now.In chapter three,a new covalent organic framework material COF-JLU5 was synthesized by condensation method of schiff base and used for organic photocatalysis.The the new 2D-COF was used as a highly efficient,metal-free,recyclable heterogeneous photocatalyst for oxidative C-H functionalizations under visible-light irradiation and O₂ as a green oxygen source owing to combining the key features such as permanent porosity,strong crystallinity,robust stability,periodic columnar π-arrays and ordered nanochannels,excellent visible absorption ability.In addition,the mechanism of photocatalytic C-H functionalization by COF-JLU5 under visible light irradiation was also studied in detail.The present work not only demonstrates the possibility of 2D-COF as outstanding heterogeneous photocatalytic platforms for organic transformations,but also expands the application scope of COFs and will promote greatly the development of the photocatalytic field.Carbazole-containingπ-conjugated systems possess intriguing photoelectric performance,and are widely utilized as electronic transmission and emission materials in organic light-emitting diodes and photovoltaic devices.The precise control of photo/electronic characteristics of conjugated polymer networks was easy implement through changing the electronic features of linker in carbozle-based monomer.In the chapter four,three D-A typed conjugated microporous polymer（DA-CMP）photocatalysts consisting of alternating electron-rich（carbazole）and electron-deficient（benzene,4,7-diphenyl-2,1,3-benzothiadiazole or anthraquinone）units have been synthesized through oxidative coupling in the presence of anhydrous FeCl₃.And their porosity and photoelectric properties including adsorption,emission,lifetime,optical bandgaps,energy levels and transient photocurrent response as well as photocatalytic activity,were conveniently tuned by selecting different D-A monomers with tunable electron-deficient moiety.In addition,the reaction mechanism for DA-CMP photocatalyzed C-H functionalization reactions under visible-light irradiation was investigated in detail.Combining the permanent porosity,outstanding stability and optoelectronic properties,the DA-CMPs were found to be excellent heterogeneous photocatalysts for the oxidative C-H functionalizations of N-aryltetradroisoquinolines with great catalytic activity,extensive substrate adaptability and outstanding reusability under visible-light irradiation and molecular oxygen.Moreover,to prove in depth the benefits of the heterogeneous photocatalysis,a continuous flow procedure has been conducted with an excellent yield,providing basic data and technical guidance for its industrial production.The bis（2-chloroethyl）sulfide well known as mustard gas or HD,that is one example for the most effective chemical warfare agents（CWA）.The selective oxidation of mustard gas into non-toxic sulfoxide analogues is considered the most promising detoxification route.However,CMP based photocatalysts for photocatalytic detoxification of a sulfur mustard or mustard-gas simulant have not been explored and reported so far.In the chapter five,we continue to investigate indeep the photocatalytic properties of carbozle-based DA-CMP（DA-CMP4 and DA-CMP5）.Two new carbazole-based DA-CMPs have been designed and synthesized by oxidation coupling polymerization,and their permanent porosity,stability and photoelectric properties.They were used as metal-free heterogeneous photocatalyst with great catalytic activity,excellent selectivity and outstanding reusability in photocatalytic detoxification of mustard gas simulant under visible-light irradiation and molecular oxygen as green oxygen source.This is the first report of selective photooxidation for mustard gas simulant using a porous organic network based material.The responsible mechanism of DA-CMP5 for photocatalytic detoxification of mustard gas simulant was also full investigated.Over the past decade,carbon dioxide（CO₂）capture and its chemical transformation into high value-added chemicals have attracted considerable attention due to a consideration of the environment and sustainable development.As a new kind of crystalline porous materials,covalent organic frameworks（COFs）,however,the field of COFs as heterogeneous catalysts for CO₂ chemical conversion remains largely untrapped.In chapter six,two triazine-based covalent organic frameworks（COF-JLU6 and COF-JLU7）were successfully designed and constructed via imine formation under solvothermal conditions.The two COF materials combine mesopores,high crystallinity and good stability,as well as a large of hydroxy groups in the pore walls.The COF-JLU7 displays high CO₂ uptake of 151 mg/g at 273 K and1 bar.Importantly,COF-JLU7 was found to be a highly effective catalyst to convert CO₂ into cyclocarbonates through the cycloaddition reaction with epoxides under mild conditions.The effect of reaction parameters,such as reaction temperature,reaction time and CO₂ pressure on the catalytic performance was still investigated in detail.Moreover,new framework-based catalyst can be recovered and reused five times without a significant loss of catalytic efficiency.