Synthesis And Sensing Propetries Of Reaction-based Organic Fluorescent Sensors

Fluorescent sensors are widely used in environmental, biological, medical, andmany other fields due to their high sensitivity, good selectivity, and the advantages ofreal-time detection. It has become a hot research topic in recent years. Among thefluorescent sensors, reaction-based sensors are designed according to the specialchemical reaction between the sensor and object, with specific selectivity and highersensitivity, are widely applied in detection of various kinds of ions and toxic chemicalsubstances. In this paper, we designed and synthesized four reaction-based fluorescentsensors, and studied their sensing properties and potential applications. The maincontents are as follows:1. Synthsis and application of sensor for cyanide detection based ontriphenylamine-indole derivitivate. A new colorimetric and turn-on fluorescentchemosensor was developed for cyanide anion with high sensitivity and selectivity inthe presence of other anions in an aqueous ethanol solution (40percents of water).The mechanism is based on nucleophilic addition reaction of cyanide anion with theindolium group blocking the intramolecular charge transfer (ICT) band of thetriphenylamine-hemicyanine dye. In addition, cyanide produced both color andfluorescence changes to the solution, and the detection limit was found to be as low as21nM. The sensing mechanism was well rationalized with1H NMR spectra andDFT/TD-DFT calculations. The live cell fluorescent experiments demonstrated thepractical value of the sensor in tracing the CN-in biological systems.2. Synthsis and study on sensing properties of ratiometric probes for detection ofcyanide. With acenaphthene and carbazole derivatives as fluorophore, indoleiodonium salt as the recognition site, we designed and synthesized two ratiometricfluorescence probes for detection of cyanide. Both of Acc and Cac exhibited highselectivity and sensitivity to cyanide detection in aqueous solution and living cells.They could achieve rapid recognition through the color changes observed by naked eye, also, could achieve quantitative analysis by fluorescence spectrum. The detectionlimits were1.3×10-6M and3.38×10-7M, respectively, which were below the WorldHealth Organization (WHO) cyanide standard in drinking water (1.9μM).3. Preparation and spectroscopy study of a triphenylamine derivirative as a probefor hydrazine detection. We prepared DPMP as a new fluorescent sensor for detectionof hydrazine based on the reaction between hydrazine and malononitrile. Hydrazonestructure generated after the reaction between hydrazine and malononitrile group,which changed the arrangement of intramolecular charge. So the color changed fromyellow to colorless, accompanied by the enhancement of fluorescence. This sensordisplayed good selectivity and sensitivity to hydrazine, with a low detection limit(1.53×10-8M). The live cell fluorescent experiments indicated the potentialapplication of the sensor in tracing hydrazine in biological systems.