Synthesis And Application Of Small-Molecule Fluorescent Probes

When the concentrations of these trace ions are abnormal,it often causes some damage to the environment or organisms.Therefore,how to accurately detect these trace ions in real time has become an important topic.Fluorescent probe is an effective and novel method because of the advantages of good selectivity,high sensitivity,simple operation,low cost,etc.Besides they have been widely used in chemistry,biology,medicine and environmental chemistry.In this disseration,we used three common chromophores:fluorescein,rhodamine and coumarin to synthesize fluorescent probes for ClO^-,S^2-,Cu²⁺,and Ag⁺.Their structure were characterized by ¹NMR.The fluorescence properties of the probes were tested by UV absorption and fluorescence emission spectra and the optical parameters were calculated based on the experimental data.?1?We synthesized a Schiff base fluorescent probe FL from fluorescein hydrazide and salicylaldehyde.The probe was used to design to detect ClO^-.When the probe FL reacts with ClO^-,we found that the fluorescence enhancement occurs.From the drawn Job's plot working curve,it was found that the probe FL and ClO^-were combined in a 1:1 ratio.Through the titration experiments of probes FL and ClO^-,the detection limit was calculated as 2.417?M,and the complexation constant was4.973×10⁷.In addition,the experiment of pH effect shows that the probe FL has good adaptability for pH.?2?By reacting between the salicylaldehyde and the rhodamine B acylhydrazone and then complexing with Cu?NO₃?₂,a quenching-type fluorescent probe Rh which has a special response to S^2-was obtained.The probe itself shows strong red fluorescence;however the fluorescence gets weakened or even disappeared after reacting with S^2-.Moreover,the probe is a good naked eye probe by the changes of its color.By the molar ratio method,we determined that the probes Rh and S^2-were reacted in a ratio of 1:1.According to the data of titration experiments,the detection limit of probe Rh for S^2-is 2.053?M,and the quenching constant is 0.049981.Moreover,the probe Rh has good adaptability for pH.?3?A probe Cn is obtained by reacting coumarin-3-carboxylic acid with2-amino-7-methyl-1,8-naphthyridine which using the coumarin as chromophore.The probe has different degrees of response to Cu²⁺and Ag⁺.In response to Cu²⁺,the fluorescence properties of the system are affected by different anions.Specifically,a new characteristic emission peak appears near 590 nm after the probe Cn reacted with CuCl₂;on the other hand the fluorescence intensity mainly reduced at 490 nm after the probe Cn reacted with Cu?NO₃?₂.In addition,the red-shift of the characteristic emission peak was observed after the probe Cn reacted with AgNO₃.The pH gradient experiment showed that the probe has good stability for pH.