Synthesis And Application Of Symmetric-substituted Anionic Tetraphenylethylene-based Fluorescent Probes

At present,most aggregation-induced luminescence(AIE)probes need to be encapsulated in water-soluble nanoparticles for applications in water due to problems such as strong hydrophobicity and difficulty in ionization.However,for analysis and detection,the analyte is often required Contact with the AIE probe can only be carried out,which greatly limits the scope of use of many AIE probes.Accordingly,the development and efficient use of ionic AIE probes can solve these problems well.In this paper,using the characteristics of AIE luminophore tetrastyrene(TPE)with symmetric reaction sites,symmetrical disubstituted and tetrasubstituted anionic TPE fluorescent probes were prepared respectively.With their good water solubility,the light-type fluorescence response of metal cations,proteins and hydrogen protons in the water environment can be achieved.The main research contents are as follows:1)Using TPE with double reaction sites symmetrical on the same side,through the ring-opening reaction of sultone,a symmetrically disubstituted TPE sodium sulfonate(TPE-diSS)was synthesized.At the same time,according to the existing literature,the symmetric and asymmetric disubstituted TPE sulfonate sodium salt(BSTPE)was synthesized as a reference.The effects of changing the solvent viscosity and increasing the poor solvent on the fluorescence signal of TPE-diSS were studied respectively,and it was confirmed that the TPE-diSS molecule has AIE properties.By comparing the fluorescence response of TPE-diSS and BSTPE to Al3+ and bovine serum albumin(BSA)at the same concentration,it can be found that the symmetric double-substituted TPE-diSS is significantly more sensitive to Al3+than BSTPE,but the detection limit for BSA(550 ng/mL)is not much different from BSTPE.Therefore,TPE-diSS and Al3+ on the same side have a stronger electrostatic attraction and tend to gather light,but the hydrophobic interaction with BSA has not changed significantly.2)Using TPE with symmetrical four reaction sites,a symmetrical four-substituted TPE carboxylic acid sodium salt(Na4TCBPE)was synthesized.The fluorescence behavior of aqueous Na4TCBPE solution was studied by increasing the concentration of Na4TCBPE or the proportion of poor solvent volume.The results showed that Na4TCBPE had significant AIE properties.Since the carboxylic acid is a weak acid,the reversible transition between Na4TCBPE and H4TCBPE can be achieved by changing the pH of the solution,and then the aggregated luminescence generated by the decrease in the solubility of H4TCBPE in water can be used to realize the llght-type response of Na4TCBPE to the solution pH.Further research on the fluorescence emission spectrum of Na4TCBPE solution at different pHs,we can find that when the pH value is 6.8,the fluorescence intensity increases suddenly and has a linear relationship in the range of 6.4-6.8.