| The BOPHY and Me4 BOPHY fluorophores have a rigid planar center-symmetric structure consisting of four rings on the same plane.There are two BF2 units in the central six-membered chelate ring,and two pyrrole rings are on the periphery.Unmodified fluorophore molecules have strong fluorescence emission,large extinction coefficient,light stability,high fluorescence quantum yield and multiple reaction sites in solution.Its derivatives have a wide range of applications in bioimaging,metal ion detection,and photovoltaic devices.In view of the excellent characteristics of BOPHY derivatives,we intend to design and synthesize high-performance fluorescent probes to realize the detection of hazardous chemicals in vapors by functionalizing their cleavage.Sarin is a nerve agent that is often used in terrorist attacks.Ethanol is the most common monohydric alcohol in life and an important industrial raw material.As a substance that is widely used in life,real-time detection of ethanol vapor becomes more and more important.Fluorescent chemical sensors are widely used in national defense safety and environmental monitoring due to their rapid response,high sensitivity,good selectivity and portability.In this thesis,the fluorescence chemical sensor is systematically described.The fluorescence detection of diethyl chlorophosphate(DCP)and ethanol is comprehensively summarized.Several kinds of fluorescent sensing materials are designed and synthesized based on the intramolecular charge transfer process.This dissertation also takes a deep research on fluorescent probe molecule’s design,synthesis,characterization and sensing performance.The main research contents are as follows:1.In the aspect of DCP detection,Me4 BOPHY was used as the backbone,and diethylamine was introduced into the α-position as a functional unit and electron donor for detecting organophosphorus reagents.Two probes were synthesized based on intramolecular charge transfer(ICT)design.Me4BOPHY-1 and Me4BOPHY-2 for detection of liquid phase DCP.After the action of Me4BOPHY-1 and DCP,the fluorescence was enhanced,the color changed from red to yellow-green,and the detection limit was as low as 40 nM.After the action of Me4BOPHY-2 and DCP,the fluorescence is enhanced,the color changes from blue to red,and the detection limit is as low as 16 nM.Both probe molecules enable dual channel detection of DCP.The mechanism of action is that the diethylamine group is conjugated to Me4 BOPHY,and a strong charge transfer(ICT)is formed in the molecule,so that the fluorescence intensity of the whole molecule is weakened.The nucleophilic addition reaction of DCP with the nitrogen atom on the diethylamine group produces an ammonium salt,which forms a hydrochloride salt under the action of a small amount of water molecules in the solution.The intramolecular ICT process is blocked,resulting in its fluorescent color change and color change.2.In the detection of ethanol vapor,a fluorescent probe Me4BOPHY-3 was synthesized by modifying the electron-donating triphenylamine functional group at the α-position of the acceptor Me4 BOPHY.In saturated ethanol vapor,the quenching rate of Me4BOPHY-3 reached 80% in 100 s,and in 300 s,the fluorescence quenching rate finally reached 91%.The response of the probe molecule to the ethanol vapor exhibits a visually visible change in color from red to blue.The detection limit is as low as 17.8 ppm.The sensing film made of the fluorescent probe molecule has good sensing effect and selectivity for ethanol vapor,and can realize color and fluorescence dual channel detection for ethanol gas.It is speculated that the detection mechanism is: Hydrogen bonding between the ethanol molecule and the F atom on Me4BOPHY-3 allows the acceptor to exhibit a larger “push-pull” electron capability,resulting in a relatively large fluorescence quenching.At the same time,the ethanol molecule can interact with the triphenylamine unit,resulting in a change in the absorption peak and a change in the aggregation state of the probe molecule,which in turn leads to a color change after the probe molecule interacts with the ethanol.In summary,this paper uses Me4 BOPHY as the framework,based on the intramolecular charge transfer process design and synthesis of three fluorescent molecular probes,to achieve efficient and sensitive detection of liquid phase DCP and ethanol vapor.It is of great significance for the design and synthesis of fluorescent probes in the long wavelength range. |
