Study On Synthesis And Application Of Quinoline Based Fluorescence Sensor

Supramolecular chemistry is in full swing,and fluorescent chemosensors in which are acclaimed among researchers and occupy a very important position in new materials and new energy sources.The detection conditions have been converted from organic solvents to aqueous media and the detection range is also from the environment to the organism.Quinoline and its derivatives have been applied to the study of fluorescent chemosensors due to their dual functions of fluorescence and detection.After chemical modification and combining with metal ions,it could exhibit significant UV and fluorescence changes,even to the naked eye.Due to its flexible synthesis and strong coordination with metal ions,Schiff base structure is introduced into quinoline derivatives to play a better role in selective recognition.In this paper,a series of fluorescent chemosensors,L1,L2,L3,L4,L5 and L6 were designed based on quinoline and their selective detection ability was investigated,respectively.The mechanism of action was inferred through a series of analysis methods.The main contents of this paper are as follows:1.Briefly introduced the development of supramolecular chemistry,the composition of fluorescent chemosensors,the recognition mechanism and its representative research,and the research advances of various fluorescent chemosensors of quinoline,according to which the design ideas were provided for this topic.2.The colorimetric fluorescent chemosensors L1,L2 and L3 were synthesized based on8-aminoquinoline,and they all selectively recognize metal ions in an aqueous medium.L1 could specifically recognize Zn²⁺?yellow fluorescence,DL:0.01?M?and Al³⁺?blue Color fluorescence,DL:0.02?M?in EtOH-H₂O solution?v/v=4/1,0.01 M,Tris-HCl buffer,pH=7.30?.When Al³⁺was present in the L1-Zn²⁺system,the fluorescence emitted steering resultin from Al³⁺could displace Zn²⁺to form L1-Al³⁺.The complex L1-Al³⁺could further recognize F^-selectivity and detection limit reached 0.09?M,which realized Zn²⁺Al³⁺and F^-detection in PC12 cells in vitro.L2 had similar property for Zn²⁺?DL:0.04?M?and Al³⁺?DL:0.14?M?in MeOH-H₂O solution?4/1,v/v?.However,complex L2-Zn²⁺and L2-Al³⁺can further detect PPi or F^-,showing a"closed"fluorescence response.In addition,the sensor L2 was capable of detecting Zn²⁺,Al³⁺,PPi and F^-in PC12 cells and achieved remarkable results.L3 selectively detected Zn²⁺?DL:0.03?M?and H₂PO₄^-?DL:0.08?M?in EtOH-H₂O?v/v=4/1,0.01 M,Tris-HCl buffer,pH=7.30?solution.It also exhibited an"off-on-off"fluorescence response accompanied by a visible color change.The addition of H₂PO₄^-to the complex L3-Zn²⁺captured Zn²⁺such that free L3 molecules was released.Fluorescence imaging of live PC12 cells demonstrated that L3 could detect Zn²⁺and H₂PO₄^-in PC12 cells.3.A visible light-excited colorimetric fluorescent chemosensor L4 was designed by using8-aminoquinoline as the precursor.In MeOH-H₂O?v/v=8/1,0.01M,HEPES buffer,pH=7.3?solution,the"off-on-off"relay recognition characteristic(?_ex:460 nm)of Al³⁺and F^-was found by fluorescence test.The detection limits for Al³⁺and F^-were calculated to be 0.10?M and 0.50?M,respectively.Based on Job's plot,¹H NMR titration and DFT calculation to infer the complexation mode between L4 and Al³⁺,and realized the application of Al³⁺recognition in PC12 cells in vitro.4.Two novel fluorescent sensors L5 and L6 were synthesized based on 8-hydroxyquinoline.In the fluorescence analysis experiments,they all produced color change that could be recognized by the“naked eye”for Al³⁺and had obvious fluorescence enhancement responses(?_ex:405 nm and 455 nm,respectively)with detection limits of 0.01?M and 0.04?M,separately.At the same time,both L5-Al³⁺and L6-Al³⁺could recognize the relay of F^-,the system were quenched by fluorescence.The whole showed an"off-on-off"fluorescence response.The detection limits were0.16?M and 0.04?M,respectively.Eventually sensors L5 and L6 both achieved intracellular detection for Al³⁺ and F^-.