Design, Synthesis And Spectral Properties Of Sensors For Metal Ions Based On Coumarin

Fluorescent probes are capable of reflecting the molecular recognition information byfluorescent signal, which is widely used in the detection of metal ions. Coumarin-basedfluorescent chemosensors have received much interest in recent years by virtue of theirphotophysics and photochemistry properties such as large stokes shift, high quantum yields.A series of fluorescent chemosensors have been described. These coumarin-basedfluorescent probes of metal ions are designed by changing the positions of recognition groupor the connected substituted species on C-3, C-4, C-6, C-7. Their recognition ability wastested by UV-vis and fluorescent spectral.Two amide compounds based on coumarin containing substituents with differentelectron-donating ability at C-7were synthesized and determined by their UV-vis andfluorescence spectra of the response of the compounds with metal ions. C-7substituent’selectron withdrawing or electron donating have a significant impact on the response of metalions. The probe A1was highly sensitive and selective for Mg2+, and A2was for Co2+.Three amides-base-coumarin probes with recognition group on C-7were synthesized andinvestigated by UV-vis and fluorescence spectral behavior in acetonitride with metal ions.We found B2was more sensitive to Cu2+than B1，while B3was to Mn2+. The fluorescencequenching phenomenon was obviously observed as low as87.5%,95.0%resepectively.Four coumarin derivatives (C1-C4) containing azo moiety on C-6were synthesized andtheir UV-vis spectra were studied. We found that they were selective for Fe3+and their UV-vis absorption intensity were increased with maximum absorption wavelength red shift.Based on the above investigation, two coumarin compounds (D1and D2) containing azomoiety on C-7were prepared, and their UV-vis absorption spectrum of the changes of free D1,D2and D1, D2in the presence of metal ions in acetonitrile were determined. That the UV-visabsorption spectrum’s different enhancement indicated the recognition of D2for Fe3+wasmore sensitive than D1.