Synthesis And Characterization Of Fluorescent Probes Containing Tetraphenylethylene Unit With Aggregation-induced Emission Effect

In recent years,fluorescent probes had attracted more and more attention from the majority of scientific workers due to their advantages such as high sensitivity,good selectivity,short response time,and so on.At the same time,the development of fluorescent materials with aggregation-induced emission（AIE）effects has opened up new research directions for fluorescent probes,making fluorescent probes with AIE effects widely used in biochemical sensors and cell imaging technologies.In this thesis,five compounds containing tetraphenylethylene（TPE）unit and three water-soluble fluorescent polymers containing TPE unit were synthesized.Based on the characterization and testing of their structures and optical properties,their Cu²⁺response and H₂O₂ response were further evaluated and tested.The main research contents and results of this thesis were as follows:1.First,the compound 1,2-diphenyl-1,2-bis（4’-aminophenyl）ethylene（TPE-NH₂）was synthesized by a McMurry coupling reaction using 4-aminobenzophenone and benzophenone as raw materials;then,7-hydroxy-4-methylcoumarin and hexamine subjected to a Duff reaction to synthesize the compound 8-formyl-7-hydroxy-4-methylcoumarin（M1）;finally,M1 and TPE-NH₂ synthesized the compound CTPE through Maillard reaction.CTPE was characterized and tested,the conclusions were as follows:in THF/H₂O mixed solvents,when the water fraction（f_w）increased from 0%to 70%,the fluorescence intensity of CTPE gradually decreased,and the maximum emission wavelength(λ_em)was 565 nm;when the f_w was higher than 70%,the fluorescence intensity of CTPE increased significantly;when f_w was 99%,the fluorescence intensity increased to maximum,simultaneously,theλ_em was red-shifted from 565 nm to 575 nm.These results showed that CTPE had significant AIE effect.Using CTPE as a fluorescent probe to detect Cu²⁺,the results demonstrated that:in the THF/H₂O（10/90,V/V）mixed solvents,CTPE emited fluorescence due to aggregation before adding Cu²⁺;CTPE complexed with Cu²⁺after adding Cu²⁺which resulted in fluorescence quenching.CTPE had a good transient response to Cu²⁺with a lower detection limit（LOD）of 0.36μM,and little interference from the other metal ions.A possible coordination model for CTPE and Cu²⁺was given.2.The compound 1,2-diphenyl-1,2-bis（4’-aminophenyl）ethylene（TPE-2NH₂）was synthesized by the McMurry coupling reaction using 4-aminobenzophenone as the raw material;and then the PEG-TPE-NH₂ fluorescent polymer containing TPE unit was synthesized by condensation reaction with methoxy polyethylene glycol acetic acid（mPEG-COOH）and TPE-2NH₂;finally the water-soluble fluorescent polymer PEG-CTPE was synthesized by Maillard reaction using PEG-TPE-NH₂ and compound M1 as raw materials.The optical properties of PEG-TPE-NH₂ and PEG-CTPE,and the Cu²⁺response of PEG-CTPE were tested.The conclusions were as follows:in THF/H₂O mixed solvent,when f_w was 100%,PEG-TPE-NH₂ emited strong fluorescence withλ_em of 500 nm;with the decrease of f_w,the fluorescence decreased sharply.In THF/H₂O mixed solvent,when f_w was1%,the fluorescence intensity of PEG-CTPE was maximum,andλ_em was 555 nm;when f_w was less than 80%,the fluorescence intensity of PEG-CTPE at 555 nm gradually decreased with the increase of f_w;when f_w was greater than 80%,the fluorescence intensity of PEG-CTPE gradually increased with the increase of f_w,andλ_em underwent a slight red shift from 555 nm to 560 nm.It was shown that both PEG-TPE-NH₂ and PEG-CTPE had AIE effect.The critical micelle concentration（CMC）of PEG-CTPE was 5.9μM.The fluorescence of PEG-CTPE was quenched immediately after adding Cu²⁺（10μM）,and little interference from the other metal ions,indicating that PEG-CTPE can be used as a fluorescent probe to quickly detect Cu²⁺in water.3.The compound 1,2-diphenyl-1-（4’-bromophenyl）-2-（4’-hydroxyphenyl）ethylene（HO-TPE-Br）was synthesized by McMurry coupling reaction using4-hydroxybenzophenone and 4-bromobenzophenone as raw materials;then HO-TPE-Br subjected to a Miyaura coupling reaction with diboronic acid pinacol ester to synthesize1,2-diphenyl-1-（4’-boronic acid pinacol esterylphenyl）-2-（4’-hydroxyphenyl）ethylene（HO-TPE-BAE）;finally,HO-TPE-BAE and mPEG-COOH were esterified to obtain polymer PEG-TPE-BAE.The maximum absorption wavelengths of HO-TPE-Br,HO-TPE-BAE and PEG-TPE-BAE were 321 nm,320 nm and 284 nm;andλ_em were 485nm,477 nm and 485 nm,respectively.When H₂O₂（100μM）was added to a 20μM PEG-TPE-BAE aqueous solution,the fluorescence intensity gradually decreased and became constant after 70 min,indicating that PEG-TPE-BAE had H₂O₂ response.In this thesis,three fluorescent probes with AIE effect were successfully synthesized,namely CTPE,PEG-CTPE and PEG-TPE-BAE.Among them,CTPE and PEG-CTPE had good selectivity and high sensitivity to Cu²⁺,can be used as fluorescent probes to detect Cu²⁺,which showed broad application prospects in the fields of chemical sensors and ion detection;PEG-TPE-BAE had H₂O₂ response,which provided new ideas for the design and synthesis of H₂O₂ fluorescent probes.