Preparation And Properties Of Fluorescent Probes Based On Rhodamine/fluorescein Derivatives

In recent years,more and more researchers pay attention to the detection of heavy metals and organic small molecules in organism.Fluorescent probe detection method has the advantages of simple operation,fast detection,less dosage and lower cost compared with the traditional detection methods researched extensive attention.Due to their advantages of high fluorescence quantum yield,good stability,long absorption and emission wavelength elongated to visible region,and fluorescence changes with the "on-off’ ring of the fluorophore,rhodamine/fluorescein probes are favored by researchers.Coumarin derivatives are also one of the most studied fluorophores.Their attractive properties such as high absorbance,high fluorescence quantum yield and large Stokes shift have attracted much attention.In this paper,rhodamine,fluorescein and coumarin were chosen as fluorophores and synthesized a series of probes,and their performances were explored.Ours studies are carried out as follows:1.Rhodamine and fluorescein were chosen as fluorophores,hydrazine hydrate were chosen as bridging chain and benzaldehyde with different substituted sites were chosen as modifying groups,seven kinds of Schiff-base probes with similar structure were synthesized.In those probes,RB-1 and RB-2 could recognize Cu2+ specifically and the color of those probes solution from colorless to red.RB-1 and Cu2+ exhibited a 2:1 ratio,the quantification of Cu2+ by RB-1 in a linear range of 0-8 μM,with a detection limit was esti,mated to be 0.25 μM.RB-2 and Cu2+ exhibited a 1:1 ratio,the quantification of Cu2+ by RB-1 in a linear range of 0-10 μM,with a detection limit was estimated to be 0.15 μM.2.Coumarin was chosen as fluorophores,5-Hydroxymethyl-2-furaldehyde was chosen as a functional group to synthesize coumarin-based Schiff base probe Rc.Rc could recognize Cu2+ specifically,the quantification of Cu2+ by Rc in a linear range of 0-25 μM,with a detection limit was estimated to be 0.24 μM.Moreover,Rc has been successfully applied to detect Cu2+ in real water.3.RB-CR was synthesized with rhodamine and coumarin and the results showed that RB-CR could specifically recognize Cu2+ in buffer with a significant change of color from yellow to bright red.RB-CR and Cu2+ exhibited a 1:1 ratio,the quantification of Cu2+ by RB-CR in a linear range of 0-10 μM,with a detection limit was estimated to be 0.12 μM.4.Rhodamine was chosen as fluorophores,ethylenediamine was chosen as a bridging chain,bromoacetyl bromide was chosen as a recognition group to synthesis rhodamine-base probe Rh-Br for glutathione detection.Rh-Br and glutathione exhibited 1:1 ratio,the quantification of Cu2+ by RB-CR in a linear range of 0-40μM,with a detection limit was estimated to be 1.08 μM.