Design,Preparation And Application Of Schiff Base Fluorescence Probe Molecules

Small molecule fluorescent probes had the advantages of low toxicity,high selectivity,biocompatibility,and visual visibility,and were widely used in detecting trace heavy metals in the environment and organisms.In this thesis,naphthyl imide,chromone and triphenylamine were used as the parent to design small molecule fluorescent probes for Al³⁺,Cd²⁺,Zn²⁺,Cu²⁺and Ag⁺,and their applications in environmental detection and cell imaging were studied.1.A novel Schiff base fluorescent probe NPP derived from naphthalimide and picolinohydrazide derivatives had been rationally designed and prepared for Al³⁺.NPP exhibited prominent sensing behaviors toward Al³⁺including low detection limit（39 n M）,rapid response time（1 minute）,strong complexation ability（4.02×10⁴）,good anti-interference characteristics and a wide working p H range.The binding ratio of NPP-Al³⁺complex was determined to be 1:1 on the basis of Job’s plot analysis.The complexation mechanism of NPP towards Al³⁺was proposed and verified by the density functional theory（DFT）and ¹H NMR titration experiment.Furthermore,this“signal-on”probe NPP has been efficiently applied as a promising indicator for Al³⁺ions in the environmental and biological systems.2.Schiff base fluorescent probe（NTP）was prepared by condensation reaction based on naphthalene imide and thiosemicarbazone unit.NTP achieved precise detection of Cd²⁺,low detection limit（LOD）（14 n M）,fast response time（2 minutes）,strong complexing ability（6.08×10⁴）,and a wide working p H range.Through Job’s plot analysis,it was found that NTP successfully coordinated with metal ions in a 1:1 ratio.At the same time,this probe was also used for intracellular imaging experiments,with low toxicity and good performance.3.Based on triphenylamine and thiazole units,Schiff base fluorescent probe（NSN）.NSN could simultaneously detect Cu²⁺and Ag⁺double ions.Among them,the detection limit（316 n M）,response time（5 minutes）,strong complexing ability（7.72×10⁴）were observed in the NSN-Cu²⁺complex.The detection limit（628 n M）,fast response time（2 minutes）,strong complexing ability（2.57×10⁵）in NSN-Ag⁺complex.The probe also had optical visualization and good anti-interference ability.In addition,using NSN to prepare test paper indicators could conveniently and intuitively detect Cu²⁺and Ag⁺.4.Using chromone-3-formaldehyde and isoquinoline 1-carbohydrazide as raw materials,a fluorescent probe ENO for the detection of Zn²⁺was synthesized by one-step Schiff base reaction.ENO exhibited excellent fluorescent response performances toward Zn²⁺over a wide p H range in Et OH/H₂O media,including a distinguished color change from colorless to gold,a low limit of detection（LOD）value（34 n M）,strong complexation ability（1.36×10⁵）and rapid identification（2 minutes）.The sensing mechanism of ENO toward Zn²⁺was proposed on the basis of the chelation-enhanced fluorescence（CHEF）process,which was further supported by IR studies and the density functional theory（DFT）calculation.In addition,ENO had demonstrated outstanding performance in monitoring trace amounts of Zn²⁺in real water samples,live cells,and on-site detection kits.