Design,Synthesis And Metal Ions Recognition Of Coumarin Fluorescent Probes

Metal ions is widespread in the natural environment and the organism.They play an important role in the biological system.So rapid detection and separation for metal ions,such as environmental protection and biological aspects are of great significance.Fluorescent probe has become a powerful means to detect metal ions because of its easy synthesis,rapid response,high sensitivity,good selectivity and many other excellent properties.Coumarin as a classic fluorescent groups,has many advantages,such as high rate of fluorescence quantum yield,a large Stokes shift,moderate fluorescence emission and absorption wavelength,light stability,low toxicity.In this paper,we designed and synthesized six novel coumarin-base fluorescent receptor,and studied their recognition properties for metal ions by UV-vis absorption spectroscopy,fluorescence spectroscopy and colorimetric.The main contents are as follows.1.7-diethylamine coumarin acyl hydrazone Schiff base(A1,A2,A3).amine Schiff base(B1,B3)and 2-(2'-amino phenyl)benzene and imidazole derivatives(B2)receptor molecules were synthesizeed.Their structure were characterized by 1H NMR.13C NMR,IR,MS,HRMS and X-ray diffraction.2.Receptor A1,A2,A3 were studied by UV-vis,fluorescence spectroscopy and colorimetric for their recognition behavior for metal ions Receptor A1 in visible light showed a very strong fluorescence,which deriving from Cu2+ fluorescence quenching in aqueous identification.For receptor A2 and A3,after the recognition for Cu2+,fluorescence enhancement were more than 39-fold and 33-fold respectively.At the same time,color recognition of receptor A1 and A3 were obvious.A 1:1 stoichiometry of receptor A1,A2,A3 towards Cu2+ were determined by Job's plot,the minimum detection limit of Cu2+ could arrive to 0.81~3.45 ?g/L.Receptor A1 and A3 could be restored by EDTA ater the recoggnition,which achieved the detection of Cu2+ "ON-OFF-ON" and could be repeated use3.Receptor B1,B2 were studied by UV-vis absorption,fluorescence spectroscopy and colorimetric for their recognition behavior for Cu2+.Receptor B1 identified Cu2+ in aqueous after the intensity dropped to the original 1/1000,accompanied by light yellow to pink color change and strong anti-jamming capability.For Receptor B2,after the recognition for Cu2+,the fluorescence enhancement was more than 13-fold,from colorless to light yellow.Receptor B3 can be used to detect Fe3+ in ethanol:water(3:2,v:v),and the fluorescence enhancement was more than 77-fold.A 1:1 stoichiometry of receptor B2,B1 towards Cu2+ were determined by Job's plot,the minimum detection limit was 0.63?1.92 ?g/L.Receptor B3 with Fe3+ is formed a I:1 complex,the minimum detection was 1.94 ?g/L.