Fluorescent Recognition For Copper Ions Based On Coumarin Pyirdiniuar

Copper ion is not only important metal pollutant but also the basic element of living tissue,the qualitative and quantitative detection of copper ion is of important practical significancefor life science and environmental protection. Although the research about supramolecularchemistry is very active that based on copper ion fluorescence molecular probe, there is acertain research space for probe of new structure that is suitable for aqueous system and couldlead to probe fluorescence enhancement. Coumarin fluorophore has many advantages becauseof benzene and pyrone structure such as high yield of fluorescent quantum, large Stokes shift,adjustable physical and chemical properties and excellent light stability. It is often used todesign metal ion fluorescence molecular probe. Therefore, research about fluorescentmolecular probes with the structure of pyridine salt based on Coumarin fluorophore hasattracted much attention.In this paper, a series of pyridine salt coumarin fluorescent probes (S-2, S-4, S-6, S-8, S-10)have been designed and synthesized. Their structures were identified by1H-NMR and MS. InTris-HCl solution (0.02M, CH3OH/water=8/2, v/v, pH7.2), the series probes examine therecognition effect for metal ions (K+, Na+, Ca2+, Mg2+,Cd2+, Ag+, Fe3+, Pb2+, Cr3+, Hg2+,Co2+,Ni2+, Cu2+, Zn2+). The results showed that series probes exhibited Cu2+-only sensitiveamong metal ions. The addition of Cu2+led to26~28nm blue-shift in absorbance maximum,an obvious color change from yellow to pale green,17~20nm blue-shift in fluorescencemaximum and2.2~8.3-fold fluorescence enhancement especially for S-6. Due to the changingof alkyl chain of series probes, lead to recognition effect for Cu2+is different.The series probes examine the recognition effect for copper ions in Tris-HCl solution (0.02M, THF/water=8/2, v/v, pH7.2) and in adding cationic surfactants to this system. Theresearch result has showed that fluorescence ranged from quenching to strengthen andmultiples increased gradually in different systems without surfactant. Indicates that alkylchain length and the fluorescence intensity improved synchronously; In addition, thefluorescence intensity increased before reduced with the alkyl chain length increased inadding cationic surfactants system. Because probes alkyl chain length has an influence in itsexisting way in cationic surfactants micelle, and then affect the recognition performance.