Study On Fluorescent Probes Based-on Coumarin For Transion Metal Ions

Accurate quantitative analyzing and detecting in situ transition metal ions is of greatsignificance for medicine, chemistry and environmental science. fluorescent probe detectionhave some outstanding advantages such as single molecule observation in situ, highsensitivity, good selectivity, not destructive and noninvasive detecting sample, etc. Coumarincompounds as fluorescent materials have many advantages such as adjustable photophysicaland photochemical properties, high fluorescence quantum yield, large Stokes shift, and highstability against light, etc. Therefore, fluorescent probe based on coumarin dyes are a majorresearch hotspot.In this paper, the design and synthesis of coumarin fluorescent molecular probes areL1-3, Their structure are identified by1HNMR and MS; In different buffer solution,recognition effect of L1-3are investigated for metal ions such as (K+, Na+, Ca2+, Mg2+, Cd2+,Ag+, Fe3+, Pb2+, Hg2+, Cr3+, Co2+, Ni2+, Cu2+, Zn2+);In Tris-HCl neutral solution（0.02M,C2H5OH/water=8/2, v/v, pH7.2）, L1only has a sensitive recognition for Cu2+.Upon theaddition of Cu2+,absorption spectrum have a148nm red-shift, the solution turns pink color,fluorescence spectroscopy quench, quenching rate is95%; In DMSO solution, the bindingstoichiometry is1:1between L2and Zn2+，L2has an effective identification for Zn2+. Uponthe addition of Zn2+, absorption spectrum have a14nm red-shift, fluorescence spectroscopyhas a18nm blue-shift and the fluorescence has a3.5-fold intensity enhancement; In HEPSneutral solution（0.02M, DMSO/water=8/2,v/v,pH7.2）, L3has an effective identification forCu2+. Upon the addition of Cu2+, there are a86nm red-shift in absorption spectra, thefluorescence quench，quenching rate is93%and the solution color change from pale green topink; In HEPS neutral solution（0.02M, CH3CN/water=7/3,v/v,pH7.2）, upon the addition ofHg2+, there are a19nm blue-shift in the absorption spectra, fluorescence spectroscopy has a6nm blue-shift and a1.7-fold intensity enhancement and the solution color change from palegreen to yellow-brown.