Synthesis And Application Of "AIE+ESIPT" Tetraphenylethene Molecules With Salicylaldehyde Structure

The discovery of aggregation-induced luminescence（AIE）compounds effectively overcomes the concentration quenching effect（ACQ）caused by traditional fluorescent molecules,and brings new opportunities for the application and development of fluorescent materials.In addition,AIE fluorescent materials show excellent photophysical properties such as high signal-to-noise ratio and good optical stability.Tetraphene（TPE）,a classical molecule with AIE properties,has the advantages of simple synthesis,high fluorescence quantum yield and easy modification.Compounds with excited state intramolecular proton transfer（ESIPT）properties,due to the presence of alcohol-keto tautomerism,tend to produce large stokes shift,which can reduce the interference caused by spontaneous fluorescence,and help to improve the sensitivity of the molecule.ESIPT process fundamentally reduces the photochemical reaction of excited molecules and enhances their photochemical stability.In addition,the ESIPT process is very suitable for designing fluorescent probe molecules because of its double-release properties.Considering the advantages of the properties of AIE and ESIPT,this paper uses tetraphene（TPE）,benzimidazole（HBI）,benzothiazole（HBT）and benzooxazole（HBO）as the basic structural units,using Suzuki coupling reaction and aldehyde condensation reaction,three series of bioluminescent materials with dual mechanism of“AIE+ESIPT”have been designed and synthesized.The structure of the synthesized product was determined by ¹H NMR,¹³C NMR,mass spectrometry and x-ray single crystal diffraction analysis,and the optical properties of the final product in different states and the application of ion detection were further studied.The main research contents are as follows:1.Three ion probes BTY-TPE,BOY-TPE and HBIY-TPE with"AIE+ESIPT"properties were designed and synthesized.Its structure was demonstrated by NMR,mass spectrometry and crystal analysis.Interestingly,portable test paper based on BTY-TPE can be used in the cyclic detection of HCl and NH₃gas.In addition,BOY-TPE and HBIY-TPE can be used as a single probe for the detection of Cl O^–ion,which has a broad prospect for the detection of Cl O–in vivo.2.Probe 2 based on NBD substituted imidazole amino group was successfully synthesized as a fluorescent“off–on”chemical dosimeter of H₂S,and its detection was limited to the range of micromoles.Probe 2 was released by Probe 1 of the sulfur interpretation of NBD amine.After adding Zn²⁺,Probe 1 could regenerate Probe 2.In addition,the Probe 2-based test strip can sensitively detect the release level of H₂S in pork samples,so as to monitor the freshness of pork.Preliminary testing of actual water samples and cell imaging studies indicate that Probe 1 and Probe 2 have great potential for detecting H₂S and Zn²⁺in vitro and in vivo.3.The“AIE+ESIPT”fluorescent enhanced type Probe 3 based on acrylyl chloride for Cys detection was successfully synthesized,which has low detection limit and short detection time.It has important application value in the biomedical field for Cys monitoring,and provides reference for the subsequent design of fluorescent probes for Cys detection.