Study On Synthesis And Photocatalytic Performance Of Benzotrithiophene-based Conjugated Microporous Polymers

With the rapid advancement of society and global science and technology,functional porous organic polymer materials play an important role in many application fields such as gas storage,proton conduction,optical devices,and heterogeneous catalysis.Porous organic polymer（POPs）materials have set off a new trend in the field of heterogeneous catalysis due to the advantages of metal-free,diverse structures,easy synthesis,easy recycling and reuse,low cost and so on.Besides,conjugated microporous polymers（CMPs）,as a novel porous organic polymer,possessπ-conjugated framework and highly adjustable photoelectric properties,permanent micropores,highly adjustable photoelectric properties,high porosity and through the electron donor-acceptor combination to adjust the material’s redox potential and other intrinsic characteristics,which has attracted much attention in the large family of porous organic polymers.Based on the above background,three benzotrithiophene-based conjugated microporous polymers（BTT-CMPs）were designed and constructed via band-gap engineering strategy.the photocatalytic performance of conjugated microporous polymers can be adjusted flexibly via adjustment of linkers,band gap and energy level,which aimed to screen the best photocatalysts from three CMPs.In the third chapter,we specifically describe the synthesis of three benzotrithiophene-based conjugated microporous polymers.Firstly,2,5,8-triethynylbenzo[1,2-b:3,4-b’:5,6-b’’]trithiophene,2,5,8-tribromobenzo[1,2-b:3,4-b’:5,6-b’’]trithiophene monomers were synthesized according to previous literature reports.whereafter,utilizing the coupling reaction between monomers to prepare BTT-CMP1,BTT-CMP2,BTT-CMP3.Besides,the structural and morphological characterization,the photoelectric properties of three materials were described in detail.From the characterization data,it can be seen that the three materials have excellent performance in visible light absorption range,specific surface area,photoelectric performance and stability.In the fourth chapter,the application of benzotrithiophene-based conjugated microporous polymer materials in the photocatalytic synthesis of 2-substituted benzoimidazole organic reaction was investigated.Using benzaldehyde and o-phenylenediamine to synthesize benzimidazole as model reaction,the optimal reaction conditions（298K,30W 460 nm blue LED,O₂ atmosphere,ethanol solvent）and photocatalyst（BTT-CMP2）were screened out through control experiments.Next,we explored the adaptability of the catalyst（BTT-CMP2）to different substrates under optimal conditions.The results show that BTT-CMP2 has excellent photocatalytic activity in the substrate containing electron-withdrawing and electron-donating groups,as well as the heteroatom substrate and naphthenic substrate.Subsequently,BTT-CMP2 material was recycled for ten times,the catalytic activity,specific surface area,structure and morphology of BTT-CMP2 did not change significantly,which indicated the excellent stability and photocatalytic activity of BTT-CMP2.Finally,we ran a large amount of the experiment and found that the yield of the target product was still high（96%）after the end of the reaction.We highlight that this work apart from contributing a fresh strategy for screening CMP-based photocatalysts,also broadens the application of CMP materials for sustainable development.