Study On Selective Recognition Of Metal Ions By Schiff Base Fluorescent Derivative

Metal ions play important roles in environment and organisms. Thus, the development of the methodfor highly selective, sensitive and rapid detection of metal ions in environmental and physiologic systems issignificant. The fluorescent probes can selectively recognize metal ions and transmit the chemical signals tofluorescent signals which can be detected by analytical instruments. The method has advantages of highselectivity and sensitivity, simplicity and low cost. Therefor, the design and synthesis of sensitive andselective fluorescent probes have attracted increasing interest in the areas of analytical chemistry. Thestructure of Schiff base has many advantages including high fluorescence quantum, easy synthesis andexcellent light stability. Schiff base became excellent fluorophore in molecular design for fluorescencechemosensor. In this paper, three Schiff base fluorescent probes were report. This thesis consists of fivechapters.In chapter1, the application and principle of the fluorescent probes for the detection of metal ionswere summarized.In chapter2, the corresponding of salen-type Schiff base,N,N’-bis（2-hydroxy-1-naphthaldehyde）-l,2-Phenylenediimine （NAPPDIH） towards chromium（III） wasstudied. Cr³⁺could quench the fluorescence of the probe. The NAPPDIH-Cr complex gave65℅fluorescence decreased with8.0×10^-6mol/L Cr³⁺at pH3.5（NH4OAC-HCl） in DMSO/H₂O （v/v,8:2）medium. A good linearity between the decreased fluorescence intensity and the concentration of Cr³⁺from5.0×10^-7to8.0×10^-6mol/L was established with a detection limit of3.7×10^-7mol/L. The method could beused to directly detect trace level Cr³⁺in different water samples.In chapter3, the selective responding of salen-type fluorescent probe,N,N’-bis（2-hydroxy-1-naphthaldehyde）-l,2-Phenylenediimine（NAPPDIH） to Mg²⁺was studied. Thefluorescence and UV-Vis titration experiments indicated that NAPPDIH bound Mg²⁺at the molar ratio of1:1. With the binding of NAPPDIH to Mg²⁺, the fluorescence spectra exhibited a specific enhancement, theUV-Vis absorption exhibited a red shift, and a naked eye color varied from pale yellow to deep yellow. The influence of other metal cations on the fluorescent spectra of NAPPDIH was investigated, the resultsshowed that the fluorescence intensity of NAPPDIH could be greatly increased only by Mg²⁺ions. Besides,a good linearity between the enhanced fluorescence intensity and the concentration of Mg²⁺from3.0×10^-6M to5.0×10^-5M was established. NAPPDIH was predicted as a fluorescent probe to rapidly detectMg²⁺.In chapter4, the selective responding of salen-type fluorescent probe,N,N’-bis（8-hydroxyquinoline-2-carboxaldehyde）-l,2-Phenylenediimine（CARPDIH） to Cu²⁺was studied.The sensor exhibited a good selectivity and sensitivity toward Cu²⁺in V（DMSO）:V（H₂O）=9:1. Thefluorescence and UV-Vis titration experiments indicated that CARPDIH bound Cu²⁺at the molar ratio of1:1. With the binding of CARPDIH with Cu²⁺, a naked eye color varied from colorless to pale green. Theinfluence of various metal ions, such as Ca²⁺, Fe³⁺, Hg⁺, Mn²⁺, Co⁺, Al³⁺, Pb²⁺, Cd²⁺, K⁺, Zn²⁺, Mg²⁺, Cr³⁺,Ni⁺and Na⁺ions on the fluorescence spectra of CARPDIH in the present of Cu²⁺was studied. The resultsshowed that other mental ions exhibited no interference. Besides, a good linearity between the decreasedfluorescence intensity and the concentration of Cu²⁺from3.0×10^-6to2.0×10^-5mol/L was established.CARPDIH was predicted as a fluorescent probe to rapidly detect Cu²⁺.In chapter5, a Schiff base fluorescence probe,N-（（2H-benzodimidazol-2-yl）methylene）benzene-1,2-diamine（BMBD） exhibited pronounced Cu²⁺andFe³⁺-selective fluorogenic behaviors. A distinctive ON-OFF-ON type signaling was observed for Cu²⁺andFe³⁺ions. BMBD showed an IMPLICATION logic behavior toward two chemical inputs of Cu²⁺and Fe³⁺ions.