The Syntheses And Applications Of Small-molecule Fluorescent Probes Based On Coumarin Fluorophore

Fluorescent probes are indispensable tools which can transfer the molecular recognition events into fluorescent signals in modern scientific and medical research areas,such asmolecular biology,biochemistry,materials science,environmental chemistry,clinical diagnostics,and food analysis.The coumarin and its derivatives have been widely used in organic fluorescent materials due to their good fluorescence properties including large Stokes shift,high fluorescence quantum yield,good light stability and other excellent features.The synthesis and application of fluorescent probes comprising coumarin ring as fluorophore has become a research hotspot in recent years.In this thesis,three kinds of coumarin fluorescent probes were designed and synthesized by using coumarin ring as the fluorescent core.1.Two derivatives of 7-hydroxycoumarin amino acid were synthesized and purified.Their structures were confirmed by NMR spectroscopy.Results show that our synthetic and purification method can provide them with high yield and purity.The UV absorption and fluorescent spectra of these two derivatives at different pH value indicate that they have different fluorescent properties compared with7-hydroxycoumarin amino acid.It will extend the range of applications of coumarin typenon-naturalaminoacidsinbiologicalstudiesoncethe aminoacyl-tRNAsynthetase/tRNA pairs for them are successfully evolved.2.Fluorescent probes with aminooxy group?-ONH₂?as the reactive group were designed and synthesized,and their fluorescence properties and applications in the field of sugar labeling were studied.It has been found that these O-substituted hydroxylamine probes show excellent fluorescence properties and can be applied to the derivatization with sugars such as D-glucose,D-mannose,maltose and other practical samples through a reductive oxyamination reaction.High performance liquid chromatography and mass spectrometry are used for the analysis of the derivatization and the results indicate that such O-substituted hydroxylamine probes show excellent sensitivity and selectivity in the detection of carbohydrates.Such probes have promising poteintal to be used in more applications in the field of carbohydrate labeling and analysis.3.Two small fluorescent probes with long aliphatic chain and N-substituted coumaryl hydroxylamines?-NHOH?used as the reactive group were prepared in 8steps with a novel synthetic protocol.Their fluorescence properties and applications in aldehyde labeling were then stuied.It was found that those two long aliphatic chain with hydroxylamine?-NHOH?substituted coumarin fluorescent probes can obviously improve the chromatographic separation and the ionization efficiency in mass spectrometry.At the same time,the derivatization reactions with aldehydes also show that those derivatization can occur under relatively mild conditions and can easily be analyzed and detected.The excellent fluorescent properties of those two fluorescent probes validate the correctness of choosing coumarin as the fluorophore in the derivatization agents.It is expected that such probes will show a bright future in the detection of aldehydes in foodstuffs and saccharides.