Design,Systhesis And Applications Of Coumarin-based Small Molecule Fluorescent Probes

Fluorescence detection stands out from all other technologies due to its high sensitivity,high selectivity,easy operation,rapid response,temporal and spatial resolution and visualization,and it has obtained extensive attention in various fields.In particular,fluorescent probes on small-molecule compounds are developing vigorously in environmental detection,industrial pollutants and biological systems.In this thesis,coumarin is used as the fluorescent matrix,combined with quinoline and tetraphenylethene functional groups,based on the mechanism of aggregation-induced emission（AIE）and twisted intramolecular charge transfer（TICT）,two types fluorescent probe are designed and prepared for a wide range of p H response and detection ofβ-galactosidase sensitively.The specific content are as follows:Chapter 1,the introduction of fluorescent probes and the research progress of coumarin-based fluorescent probes.Chapter 2,based on the mechanism of AIE,a fluorescent probe for p H detection was designed and developed.The probe was obtained by connecting electron donor coumarin groups and electron acceptor quinoline groups through hydrazide bond.In different p H media,the probes exhibit different molecular structures,which lead to changes in the optical signal（wavelength and intensity）to achieve the purpose of responding to the p H of the medium.Different from the p H-responsive fluorescent probes previously reported,the probe can achieve a response to the wide range of p H（2.0-12.0）with different changes in fluorescent signal.In addition,the probe can quickly identify the acidity and alkalinity of media by changing of the colors under a UV_{365 nm} light.Further,the probe can be prepared as a p H-detection paper for the intuitive detection of p H,which provides a theoretical basis and application reference for the development of p H probe with high sensitivity,wide detection range and simple and practical based on the light response mode.Chapter 3,based on the competition between TICT and intramolecular charge transfer（ICT）,a highly sensitive fluorescence-enhanced probe TC-gal for the detection ofβ-galactosidase was designed and developed.The probe consists of twisted group tetraphenylethene,fluorescent reporter group coumarin and recognition group galactose.The experimental results show that the probe TC-gal has highly selective,ultra-highly sensitivety(LOD=8.4×10^-5 U/m L)and strong affinity（Km=18.4μM）forβ-galactosidase.Furthermore,the probe TC-gal has good biocompatibility and can be used to detect endogenousβ-galactosidase in ovarian cancer cells and distinguish senescent cells.The research work provides new ideas for the design and development of probes with high sensitivity and applications in biological fields.Chapter 4,summary and prospect.