Study On The Application Of Pyrene-based D-A Conjugated Polymer And Monomer In Photocatalytic Oxidation

Pesticides play important roles in crop production,however,the environmental pollutions caused by pesticides that cannot be ignored.At the same time,the concept of green chemistry also points out the direction for the development of pesticides.Including the development of new synthetic methods to discover new pesticides,reducing pollution during the pesticide production process,improving atomic utilization,exploring mild synthetic conditions,and reducing energy consumption.Oxidation reaction is one of the important types of organic reactions and plays an important role in organic synthesis.At the same time,the oxidation reaction also has a wide range of applications in the field of organic pollutants treatment.Therefore,studying the oxidation reaction is very important to the synthesis and degradation of pesticides.The oxidation reaction is inseparable from the participation of oxidants.However,traditional oxidants such as high-priced metal salts,metal oxides,and organic peroxides have the disadvantages of large pollution and high cost.Oxygen is a component of air,with low price and no pollution in the final oxidation product.It is an ideal green oxidant.Visible light is an important kind of renewable clean energy.In recent years,with the increase of people’s awareness of environmental protection,photocatalytic reactions have become a hot spot for researchers.The photocatalytic oxidation reaction involving oxygen provides a new method to produce pesticides and the treatment of pesticide pollution.Photocatalysts are the key to photochemical conversion,and the development of photocatalysts with high-efficiency has always been an important research direction.At the same time,in the photocatalytic oxidation reaction,the research of reactive oxygen species(ROS)is of great significance.Because in different reactions,the ROS species roles in the reaction are different.Therefore,regulating the production of specific ROS species through the structural design of photocatalysts has great significance for the study of photocatalytic oxidation reaction mechanism and photocatalysts.Based on this,this thesis focuses on the following work:(1)Pyrene-based conjugated organic polymers in the regulation of ROS species.In this section,two pyrene-based CMPs photocatalysts were designed and synthesized.The introduction and removal of alkynyl groups realized the regulation of ROS species in the photocatalytic oxidation reaction.The above two catalysts are used for the oxidation reaction of thioether and the coupling reaction of amine.It is proved that in the oxidation reaction of thioether,the ROS species participating in the reaction is 1O2;in the oxidative coupling reaction of amine,the ROS species participating in the reaction is ·O2-.At the same time,the applicability of the two photocatalysts in the coupling reaction of photocatalytic oxidation of thioether and benzylamine was verified in the study of substrate applicability.The amount of catalyst can be as low as 0.1%-1%.(2)Pyrenyl D-A organic monomer in photocatalyst oxidation reaction.Organic small-molecule photocatalysts are easy to prepare and modify,which is conducive to property regulation and mechanism exploration.However,most of the current organic small-molecule photocatalysts have poor stability and are homogeneous catalysts,which are not conducive to reuse.This study found that the pyrene-based organic monomer has certain photocatalytic performance but with low efficiency,and the small-molecule has poor solubility in various solvents,and displays the potential as a heterogeneous catalyst.Therefore,the introduction of electron-withdrawing and electron-donating groups into the pyrene-based organic monomer,and the of alkynyl groups as a bridge for electron transfer that constructed planar molecules,greatly improve the catalytic efficiency of the pyrene-based organic monomer photocatalyst,and the amount of catalyst is reduced to 0.1%.At the same time,the stability of the small-molecule catalysts are improved,and the catalytic effect is still good after multiple cycles.In the study of substrates tolerance,it was confirmed that it has good tolerance in photocatalytic oxidation of thioether,benzylamine coupling and arylboronic acid oxidation reactions.In this study,by adjusting the structures of CMPs photocatalysts,the control of ROS was realized,and the detailed mechanism of amine oxidative coupling and thioether oxidation was confirmed.In addition,a series of small-molecule based photocatalysts with highly efficient heterogeneous were synthesized,which enhanced the economy and environmental friendliness of the small molecule photocatalyst.