Preparation Of Conjugated Organic Polymers And Their Sensor Properties For Hydrazine

Conjugated organic polymer is a type of functional material with broad application prospects that is constructed by connecting different organic modules through strong covalent bonds.It has the characteristics of high thermal stability,low density,adjustable structure and function,etc.It is used in sensing,catalysis,energy storage and other aspects have huge application potential.Conjugated organic polymers can generally be divided into two types:amorphous and crystalline.Amorphous conjugated organic polymer has a conjugated molecular wire structure,and the partial infinitesimal disturbance can be amplified and utilized in the entire conjugated system.At the same time,it has weaker interlayerπ-πinteraction,so that the fluorescence properties are improved.Therefore,conjugated organic polymers can be used for the sensing and analysis of trace amounts of analytes,and can exhibit a sensitivity that is stronger than that of organic small molecule fluorescence sensors.Crystalline conjugated organic polymers such as covalent organic frameworks（COFs）have the advantages of large specific surface area,adjustable pore size and structure,etc.,and have been widely used in gas storage,photocatalysis,fluorescence sensing,ion conduction,material separation and recovery and other fields.Hydrazine is an important chemical raw material with strong alkalinity and reducibility.It is widely used in pharmaceutical,chemical,aerospace and other fields.However,hydrazine is highly toxic.When it enters the human body through the eyes,mouth and skin,it will seriously damage the liver,kidneys,lungs and the human central nervous system,and even cause cancer.For this reason,it is particularly important to explore an efficient and sensitive hydrazine detection method.Therefore,this paper designed and synthesized two types of polymer materials,namely amorphous conjugated organic polymers with specific functional groups and crystalline covalent organic backbones.The fluorescence intensity of polymer is affected by the interaction of specific functional groups in the polymer with hydrazine,so as to realize the detection of hydrazine.The specific research content is as follows:1.Synthesis of Conjugated Organic Polymer COP-Ta and Its Sensing Properties for HydrazineThrough Sonogashira coupling reaction of tetrakis（4-ethynylphenyl）ethene（TPE-Al）containing AIE luminophore and terephthaloyl chloride（TPC）,the amorphous conjugated organic polymer COP-Ta containing ynone structure was synthesized.COP-Ta has an amorphous structure and good thermal stability.The ynone structure in COP-Ta can interact well with hydrazine in the aqueous solution,thereby changing the structure of COP-Ta and making its fluorescence enhancement,so that COP-Ta can be used for the detection of hydrazine in aqueous solution.Through FT-IR and solid-state¹³C NMR,it is proved that hydrazine can cyclize the ynone structure in COP-Ta to pyrazole,inhibiting the ICT process in COP-Ta,and ultimately its fluorescence is significantly enhanced.2.Synthesis and properties of covalent organic framework TAPB-DHE and TAPT-DHETwo covalent organic frameworks TAPB-DHE and TAPT-DHE with similar structures were synthesized by acetic anhydride with Dha Tab and Tz Da through esterification reactions,respectively.Crystalline COFs have a larger specific surface area,high porosity,and ordered pore structure,which can provide a larger space for the penetration and interaction of analytes.Compared with TAPT-DHE,the structure of TAPB-DHE has an ICT process from triphenylbenzene to an ester group,and the presence of hydrazine will convert the ester group into a hydroxyl structure,thereby inhibiting the ICT process in TAPB-DHE,and making it fluorescence enhanced,so TAPB-DHE can be used for the detection of trace hydrazine in aqueous solution.However,TAPT-DHE,which doesn’t have the ICT process in the structure,doesn’t show the sensing performance for hydrazine.