The Synthesis And Application Research Of Fluorescent Probes With Large Stokes Shifts

Fluorescence imaging technology has aroused the widely attention of researchers due to its good repeatability and real-time imaging,etc.And organic small molecule fluorescent probe have become an important tool for fluorescence imaging because of its speed,high selectivity,good biocompatibility,and so on.Organic small molecule fluorescent probes which have been reported still need to improve in photophysical or photochemical propertie.So,it is necessary to construct a novel fluorescent probe with excellent photophysical and photochemical properties.Stokes shift is an important photophysical parameter of fluorescent dyes.Large Stokes shifts not only reduce the effect of excitation light on fluorescence measurements,but also avoid the self-quenching character,which are beneficial to improve the sensitivity of fluorescent probe and the reliability of the detection.The Stokes shifts of most organic small molecule fluorescent probes which have been reported are from 20 nm to 70 nm,and it greatly limits the imaging application of cells and living organisms.In this paper,in allusion to this problem,we have constructed three novel organic small molecule fluorescent probes with large Stokes shifts,and examined its various applications.Detailed research contents are as follows:In the second chapter,a novel fluorescent probe KZTZ was synthesized by introducing ?,?-unsaturated ketone onto carbazole.The recognition is based on the additive reaction of sulfhydryl toward the ?,?-unsaturated ketone,and the homocysteine and cysteine can be identified by naked eyes under day light or a 365 nm UV light.The probe showed a large Stokes shift(128 nm)upon recognition,and the probe was used for fluorescence imaging and quantitative detection of homocysteine in PC12 cells.In the third chapter,based on the work of the second chapter,we introduced the concept of aggregation-induced emission and excited-state intramolecular proton transfer properties,and synthesized a novel fluorescent probe SATZ by reaction of salicylaldehyde azine and 2,4-dinitrobenzenesulfonyl chloride.The recognition is based on the nucleophilic substitution reaction,and the cysteine and homocysteine can be identified by naked eyes under day light or a 365 nm UV light.Because of the excited-state intramolecular proton transfer properties of salicylaldehyde azine,the probe showed a large Stokes shift(148 nm)when detecting cysteine and homocysteine.Due to the good aggregation-induced emission properties of salicylaldehyde azine and the good sensing performance of the probe,the probe was used for fluorescence imaging of cysteine in PC12 cells.In addition,the probe was also used to make portable kit which could rapid and quantitative detection of cysteine and homocysteine in microsamples.In the fourth chapter,the dual-function fluorescent probe FSQTZ for the detection of water content and hypochlorite was synthesized by introducing aldehyde group onto phenothiazine.The probe showed strong fluorescence in organic solvent,and the increase of water content could cause its fluorescence quenching and fluorescence red shift.The probe was especially responsive to water in acetone(LOD = 0.014 wt %),so it could be employed to estimate tiny amounts of water in commercial products.The increase of hypochlorite could cause its fluorescence increasing and fluorescence blue shift in aqueous solution,and possessed the advantages of a remarkable large Stokes shift(168 nm),a rapid response time(within 10 s)and a wide pH range of response.In addition,the probe was also used for fluorescence imaging of exogenous hypochlorite in PC12 cells.