Construction And Investigation Of Fluorescent Probes For Selective Detection Of Biothiol And Sulfur Dioxide Derivative Using Coumarin As Fluorophore

GSH plays a key role in maintaining the redox homeostasis and cellular functions;Sulfur dioxide,a traditional air pollutant,influences the growth and development of plants by affecting the photosynthesis.However,moderate sulfur dioxide derivatives were in widespread use for many years as a general food additive,which was often intake by body.Therefore,it is of growing importance to develop a good method to detect GSH and sulfur dioxide derivative quantitatively,qualitatively and selectively.Coumarin widely exists in higher plants,which has received great attention due to their good properties such as large fluorescence quantum yields and easy modification.Based on the advantage of fluorescence analysis,two fluorescent probes were constructed for selective detection of GSH and sulfur dioxide derivatives by using coumarin as fluorophore.The main contents are as follows:(1)The fluorescent probe for selective detection of GSH was constructed and investigated by using coumarin as fluorophore.According to the reported literature,we synthesize a probe A for selective detection of GSH.There are electron-donating N,N-diethylamino group and electron-withdrawing group of aldehyde and halogen chloride of probe A,from the molecular structure,we find probe A exists both intramolecular charge transfer(ICT)process and the heavy atom effect,so,we can observe an emission band at 550 nm.However,with the addition of GSH,nucleophilic group of amino would attacke aldehyde of probe A and generate a thio-containing product,then,—SH of thio-containing product would attacke—Cl by the reaction of nucleophilic substitution.The above reactions not only interrupted the intramolecular charge transfer but also destroyed the heavy atom effect of chlorine atom of probe A,which resulted in a blue-shifted from 550 nm to 500 nm.Simultaneously,the fluorescence intensity at 500 nm shows a good linear relationship with the concentration of GSH(0-10 ?M),The detection limit was calculated to be 68.7 nM.(2)A colorimetric and fluorogenic probe for selective detection of bisulfite was constructed using benzopyrylium as the recognition unit.The benzopyrylium unit is easily attacked by nucleophiles to interrupt the ?-conjugation system of the dye,which resulted in remarkable influence in the optical spectra.Because benzopyrylium unit is easily attacked by nucleophiles,we constructe a colorimetric and fluorogenic probe B,which is essentially non-fluorescent due to an efficient PET process.However,with the addition of bisulfite,nucleophilic bisulfite would attack the benzopyrylium moiety and interrupt the ?-conjugation of B to inactivate the electron deficient oxonium ion,and thus the driving force for PET would be considerably diminished,thereby it is easily observed a new emission band at 510 nm.Meanwhile,a significant color change from blue to yellow was observed.It is worth to note that probe B could detect bisulfite rapidly within 30 s.Additionally,the fluorescence intensity at 510 nm is linear with bisulfite concentration in the range of 0.2-7.5 ?M with a detection limit of 42 nM.Simultaneously,we successfully applied the probe B for bisulfite detection in sugar solutions and biological samples.