The Synthesis Of Chromone And Quinoline Schiff Bases And Its Application As Probes For Detection Al³⁺,S^2-and Cu²⁺

The research of organic small molecule fluorescent probes is very active in the field of analysis and detection.It is a very meaningful task to design and synthesize highly selective probes which are water-soluble,multifunctional,easy-to-operate and naked-eye recognition for chemical analysis and detection.Combined with the previous research results in our laboratory,the probes were used to detect metal ions and small biological molecules in order to solve some problems of the current fluorescent probes have been synthesized.In this paper,3 kinds of Schiff base fluorescent probes were designed and synthesized using 6-ethoxychromone and2-hydroxyquinoline-3-aldehyde as fluorophores.Their structures were characterized by ¹H NMR,infrared spectroscopy,and mass spectrometry,and their spectral properties were also studied.The main content of the paper is divided into the following four parts:Chapter 1:Introduced the composition,development,detection mechanism,current research statu of fluorescent probes briefly.Chapter 2:An simple Al³⁺receptor,2-hydroxyquinoline-3-aldehyde-（benzoyl）hydrazone（L₁）,has been synthesized by condensing quinoline aldehyde with benzoyl hydrazide.L₁ displayed a highly selective and pronounced fluorescence enhancement for Al³⁺over other common cations in water.The selective recognition of Al³⁺by L₁ should be attributed to the interaction between the ligand and Al³⁺,which inhibits the PET process and forms a turn-ON fluorescent probe.More importantly,the probe L₁ can perform Al³⁺in pure water which provides the possibility to realize the detection of cells and organisms.Chapter 3:Based on the chromone skeleton,a simple and novel probe that is6-ethoxychromone-3-carbaldehyde-（furanyl）hydrazone（L₂）has been synthesized and completely characterized.It exhibited representative turn-on fluorescent properties and obviously colorimetric changes with high selectivity to Al³⁺and Cu²⁺.For Al³⁺,L₂ displayed a turn on green fluorescence in EtOH/H2O（3/2）aqueous media over other common cations.With Cu²⁺,L₂ perceived Cu²⁺through the naked-eye by the color changed-from colorless to yellow.Consequentially,L₂ could be used as a solid probe for both Al³⁺and Cu²⁺.Chapter 4:A chromone derivative（L₃）which could be utilized for reversibly detecting Cu²⁺and S^2-based on fluorescence quenching and displacement in aqueous solution was designed and developed.Upon the addition of Cu²⁺,the strong blue-green fluorescence emission of L₃ was quenched rapidly and then recovered in1 min by successively adding S^2-which could constitute a ON-OFF-ON system.Furthermore,with the alternate addition of Cu²⁺and S^2-,the reversible cycles could be repeated for at least four times,which meant that L₃ could be identified as a renewable dual-functioning probe.What’s more,due to its excellent sensing performances,this probe L₃ could also be used to detect Cu²⁺and S^2-with test strips conveniently.