Synthesis Of Coumarin Dyes And Its Application In Fluorescent Probes

Fluorescence detection has been widely used in medicine,life sciences and environmental sciences for its good selective and highly sensitive detection.As a classic fluorophore,coumarin has the characteristics of good photostability and high fluorescent quantum yield,and is widely used in the design of fluorescent probes.In this thesis,two new coumarin-based fluorescent probes for the detection of Hg²⁺and NO₂^-respectively,have been rationally designed and developed,as well as the development of novel indole-coumarin fluorescent dyes.1.A new coumarin-based fluorescent probe MS6 for the ratiometric detection of Hg²⁺have been designed and developed.Started from m-diethylaminophenol,the probe is obtained in a high yield by a five-step reaction such as condensation,chloro-formylation,coupling,sulfur acetal protection and reduction.The experimental results showed that the introduction of NH₂ in the probe can effectively promote the reaction rate of Hg²⁺desulfurization acetal reaction and improve the sensitivity of the probe to mercury ions.We believe that the probe MS6 may have good potential application in biological analysis and environmental detection.2.A new coumarin-based fluorescent probe NS1 for the detection of NO₂^-have been designed and developed.The probe is obtained in a higher yield by a three-step reaction of chlorination,coupling and reduction with 4-hydroxy-7-dimethyl-aminocoumarin as a starting material.Under the acidic condition of pH=2,the amino group on the probe reacts with NO₂^-to form a diazonium salt and then undergoes intramolecular electrophilic substitution reaction to form a large conjugated ring-closing structure,thereby realizing the ratiometric response.The probe NS1 has good selectivity to NO₂^-and has a fast response.In addition,the test strip of the load probe can easily and sensitively detect NO₂^-in the aqueous solution.3.A series of novel coumarin-indole dyes have been designed and developed.Eight coumarin-indole derivatives 4a-4h with different substituents were synthesized by one-step reaction from salicylaldehyde derivatives and indole derivatives,and5a-5h were obtained by followed one-step methylation reaction.The spectral properties of 16 compounds in ethanol,dimethyl sulfoxide,dichloromethane and acetonitrile were tested and the effects of substituent effects were discussed.The results show that these new indole-coumarin fluorescent dyes possess easy to obtain?one-step reaction?,large molar extinction coefficient,high fluorescence quantum yield,and large fluorescence emission wavelength.It indicates that these kind of indole-coumarin dyes have good potential application in the field of fluorescent probe.