Synthesis And Structure-property Relationship Of Aggregation-induced Emission Probes And Its Application In Cell Imaging And Sensing

Fluorescent probes have obvious advantages in chemical sensing,biosensing and cell imaging while traditional fluorescent dyes suffer from aggregation-caused quenching(ACQ)at high concentrations,which have greatly limited their applications.The concept of aggregation-induced emission(AIE)opens up a new way for the development of new fluorescent probes.The mechanism of AIE phenomenon is mainly based on restriction of intramolecular motion(RIM),fluorescence probes with the effects of restriction of intramolecular motion(RIM)and excited state intramolecular proton transfer(ESIPT)possess many advantages,such as large Stokes shift,simple synthesis and easy modification.In this thesis,we have developed a series of new AIE compounds which combined the effect of RIM and ESIPT and studied their structure-property relationship,moreover,new fluorescent probes were synthesized for heparin detection and organelle-specific photoactivatable imaging.In chapter 1,we summarized recent progress of AIE compounds and probes which based on RIM and ESIPT synergy mechanisms.In chapter 2,we have designed a series of 2-(2-hydroxyphenyl)quinazolin-4(3H)-one(HPQ)derivatives and investigated the relationship of their photophysical properties with the kind and position of substitution.Furthermore,a probe for lysosome specific imaging was designed and synthesized.In chapter 3,an AIE probe was prepared by introducing phosphonium groups and iodine anions based on HPQ skeleton.This probe has been used for sensitive and selective detection of heparin based on a synergistic strategy of AIE and displacement of the fluorescence quencher iodide ion.In chapter 4,we designed an in situ generation strategy for preparation of photoactivatable AIE probes by tandem S–S bond reduction and intramolecular cyclization reaction to in situ quantitatively generate 2-(2-hydroxyphenyl)-benzothiazolines which will undergo the photooxidative dehydrogenation reaction to afford the AIE-active compound 2-(2-hydroxyphenyl)-benzothiazoles.Photoactivatable imaging of lipid droplets(LDs)and lysosomes can be achieved by modifying targeting group.