Synthesis And Properties Of Coumarin Hybrid Fluorescent Probes

Fluorescent dyes and probes are a major bridge in exploring the microscopic world for human.Fluorescent dyes,with their good chemical and optical stability,strong environmental resistance,and good biological adaptability,are now widely used in medicine,materials,and chemical analysis,among other fields.Among them,dyes with aggregation-induced fluorescence properties play an important role in safety identification,forensic science,and criminal investigation.Fluorescent probes,on the other hand,have specific recognition capabilities and play an important role in detecting environmental safety issues related to food and water sources.In this paper,we first designed and synthesized a novel coumarin probe CP2 for the specific recognition of H₂S,followed by designing two new coumarin derivative dyes D-2 and H-2 with pH sensitivity,as well as a coumarin solid dye L-2 with aggregation-induced luminescence properties.The main content is as follows:Firstly,we designed a fluorescent probe based on the coumarinβ-diketone structure with diethylamino group.The use of coumarin as the fluorescence unit was considered due to its good biological adaptability and environmental tolerance.We selected the 2,4-dinitrophenylsulfanyl group as the recognition group because the phenylsulfanyl group is easily attacked by HS^-nucleophiles,which can restore the fluorescence of the fluorescent unit.Then,photophysical testing and live cell fluorescence imaging were performed,demonstrating that the probe can specifically recognize H₂S and detect H₂S in water samples with high sensitivity,as well as effectively detecting endogenous and exogenous H₂S in live cells.Secondly,we synthesized two new fluorescent dyes,both of which have a coumarin core and a 3-position imidazole ring electron-withdrawing group,with different electron-donating substituents at the 7-position.Both dyes showed high fluorescence quantum yield and large Stokes shift in photophysical testing,with high quantum yield in ultra-pure water.The good photophysical properties and the trend of fluorescence changes with environmental pH make the two new dyes have the potential to become pH fluorescent indicators.Finally,by using 4-hydroxybenzaldehyde as the starting material,a new coumarin-β-diketone dye was synthesized through Claisen condensation and substitution reactions.This dye has the property of aggregation-induced fluorescence.The dye was dispersed in montmorillonite to make fingerprint powder,and the performance of the fingerprint powder was tested under different materials and backgrounds.Clear secondary and tertiary nodes and ridge features in the imaging results demonstrated that the new dye has great potential as a fluorescent fingerprint powder and is expected to be applied in specific fields in the future.