Synthesis And Properties Of Fluorescent Probes Based On Quinoline

Metal ion pollution has caused great harm to the ecological environment and human health withthe development of industries such as chemical industry,military manufacturing industry,mining and metallurgy.Therefore,how to quickly and effectively identify the presence of metal ions in the environment and target samples has a very practical significance.Even though there are many detection methods nowadays,due to complicated sample processing,real-time detection is not effective,the cost is too high,and the most important thing is that reasonable detection of metal ions in living cells and living body cannot be performed.In this paper,quinoline was used as a fluorophore,and its chemical modification was made to achieve the purpose of specifically identifying metal ions and detecting metal ions in living cells.In this thesis,fluorescent probes based on 8-aminoquinoline fluorophores were designed andsynthesized,and their structures were confirmed by ¹H NMR,¹³C NMR,MS and IR.The binding properties between these probes and common metal ions and anions were studies by fluorescence spectroscopy.In addition,metal complexes as new probes were used to identify citric acid radical in aqueous media.This thesis is divided into five chapters,and the main contents are as follows:?1?The design principle of molecular recognition and fluorescence chemical sensor is reviewed.The research progress of quinoline fluorescence probes to metal ions and anions is introduced.Based on this,the design idea of this thesis is proposed.?2?Four novel fluorescence probes bearing quinolylbenzothiazole platform were synthesized and characterized.The probes displayed excellent selectivity,high sensitive fluorescence response to Fe³⁺ion in H₂O-DMSO buffer solution?1:4,volume ratio,Tris-HCl 0.01 M,pH=7.40?and showed no appreciable change in fluorescence spectrum.The binding stoichiometry between probes L1,L2,L3 or L4 and Fe³⁺were observed to be 1:1 based on fluorescence titration and Job's plot analysis.The detection limits of L1,L2,L3 or L4 for Fe³⁺were found to be 0.155,0.362,0.249,0.517?M,respectively.Further,possible utilization of probes as bio-imaging fluorescence to detect Fe³⁺in living HeLa cells were also investigated by confocal fluorescence microscopy.?3?Anovelquinoline-derivedSchiffbasefluorescentCu²⁺ionprobe2-?2-hydroxybenzylidene?hydrazono)methyl)quinolin-8-ol?L5?was synthesized and characterized by various analytical techniques.On the addition of Cu²⁺ion to the solution of L5,the solution color changed from colorless to yellowish green and fluorescence emission exhibited“turn-on”response.The UV-vis and fluorescence spectroscopic experiments showed that the L5 could serve as a high selectivity and sensitivity probe for the detection of Cu²⁺ion at physiological pH.The stoichiometry of probe L5 and Cu²⁺was found to be 1:1 by fluorescence titration,Job's plot and HRMS analysis.FT-IR and density functional theory?DFT?calculations were also conducted to understand the sensing behavior of probe L5.Furthermore,this fluorescence probe has been successfully applied to detect Cu²⁺ion in living cells.?4?Two novel fluorescent probes?L8?and?L9?were designed and synthesized.Their selectivity for Cu²⁺and Fe³⁺ions was studied in aqueous solutions,and Cu²⁺and Fe³⁺were distinguished by color change.The detection limits of probes L8 and L9 for Cu²⁺ions were 2.14×10^-8 M and 2.70×10^-8 M,respectively.L8-Cu²⁺and L9-Cu²⁺complexes could selectively identify citrate ions.Probes L8 and L9could be used as an"On-Off-On"fluorescence switches.In addition,the fluorescence quenching by Cu²⁺could be completely reversed by adding citrate,and this"on-off"switching process could be repeated several times with almost no fluorescence loss.In addition,the detection of Cu²⁺and citrate anions in live cells using probes L8 and L9 was studied by cell imaging experiments,which indicating that probe L8 have potential applications.