Synthesis And Spectral Properties Of Novel Fluorophore Based On "AIE + ESIPT" And Its Application In Biothiol Imaging

Fluorophores based on the "AIE + ESIPT" mechanism have some merits,such as no self-quenching at high concentrations,large Stokes shift and high signal-to-noise ratio,hence they show great advantages and application prospects in chemical sensing,biosensing and imaging.In this dissertation,synthesis and spectral properties of novel fluorophore based on "AIE + ESIPT" and its application in biothiol imaging were studied,which were discribed in three chapters as followed.Chapter 1,we illustrated the luminescent mechanisms of aggregation-induced emission(AIE)and excited-state intramolecular proton transfer(ESIPT)at first,as well as their representative compounds.Then,from the viewpoint of structural feature,we have divided the fluorophores based on the "AIE + ESIPT" mechanism into two main types:(1)the AIE unit is equal to the ESIPT unit;(2)The independent AIE and ESIPT units are ligated via covalent bonds.They were discussed in detail.In Chapter 2,inspired by previous studies,we designed and synthesized the third class of "AIE + ESIPT" fluorophore TPE-HBT by intersecting AIE unit(TPE)and ESIPT units(HBT),at the same time,we also synthesized controls of TPE-1,TPE-2 and HBT.Through the analysis the fluorescence spectrums of TPE-HBT in different test conditions and fluorescence spectrums of TPE-1,TPE-2 and HBT,we proved that there exist ESIPT and AIE mechanisms in TPE-HBT,we also found that the two kinds of mechanisms have a synergistic effect in TPE-HBT molecule.In addition,the TPE-HBT has superior performance,its Stokes shift is more than 200 nm,the solid-state absolute fluorescence quantum yield is as high as 0.97.The photostability of TPE-HBT is good,and the cytotoxicity is low.In Chapter 3,considering the good photophysical properties of TPE-HBT,we have developed a new fluorescent probe TPE-3 by modifying the hydroxyl in TPE-HBT,which can detect of biothiols(Cys,Hcy,GSH,H2S).The selective and competitive experiments showed that TPE-3 has a specific recognition effect and good anti-interference ability to biothiols.In addition,the response rate of TPE-3 to biothiols is fast,and the maximum response intensity can be reached within 15 min.The detection limits of TPE-3 for Cys,Hcy,GSH and H2S are 72 nM,90 nM,81 nM and 82 nM,respectively.The cytotoxicity of the TPE-3 is low,and we applied it to the fluorescence imaging of biothiols in HeLa and HuH-7 cells,indicating its potential application value.