The Synthesis And Application Of Novel Rhodamine B-based Metal Ion Fluorescent Probe

Among so many detection methods, the method of fluorescent molecular probe has attracted muchattention due to its advantages of good selectivity, high sensitivity,“off-on” switch ability, etc. Therhodamine B derivatives are a kind of excellent fluorescent chemosensors due to its prominentphotophysical properties, such as long absorption and emission wavelength, high fluorescence quantum,excellent rigid planar structure, favorable solubility in water, low toxicity, and their maximum emissionwavelengths are in the visible light region. This dissertation described the design and synthesis of5rhodamine amide derivatives, the recognition performance, response mechanism and actual application inaqueous solution were investigated.1. A rhodamine B derivatives fluorescent probe P1was designed and synthesized, and the absorptionand fluorescence spectrum of P1with metal ions was investigated. The results showed that, upon additionof Cu²⁺, the P1exhibited fluorescence enhancements, and the obvious color change of solution wasappeared. Optimal pH and response time of P1with Cu²⁺was determined by researching conditionexperiment. With the optimum condition described, the response was linearly proportional to theconcentration of Cu²⁺in the range5.0×10^-6mol/L^-5.5×10^-5mol/L with a detection limit of4.9×10^-7mol/L.According to the method of Job’s plot, determined the complexing ratio was1:1of Cu²⁺and P1, and apossible coordination mode for P1with Cu²⁺was proposed.2. Two Pd²⁺fluorescent probe RD and RA were designed and synthesized, the qualitative andquantitative detection in media aqueous were investigated, respectively. The results showed that, the probesboth of RD and RA can be used as a fluorescence enhanced Pd²⁺fluorescence probe, and have the singleselectivity and low detection limit. The response mechanism was discussed by the analysis of Job’s plot andmass spectroscopy. Probe RD and RA were preliminarily applied in the determination of Pd²⁺inpalladium-containing catalyst, river water and tap water samples. And, RA cans intracellular Pd²⁺imagingin Arabidopsis guard cells.3. A rhodamine B-based fluorescent probe RF was designed and synthesized, RF showed highselective recognition toward Cr³⁺over other examined metal ions in Tris-HCl (1.0×10^-2mol/L, pH=7.2) aqueous buffer solution. Quantitative results showed that the response was linearly proportional to theconcentration of Cr³⁺in the range0-1.0×10^-5mol/L with a detection limit of2.3×10-8mol/L. Highlyselective and sensitive detection method for Cr³⁺was successfully applied to water samples analysis andintracellular Cr³⁺imaging in Arabidopsis guard and PC12cells.4. A rhodamine B-based fluorescent probe RP was designed and synthesized as a highly selective andsensitive probe for Hg²⁺in Tris-HCl （1.0×10-2mol/L, pH=7.2） aqueous buffer solution. Quantitativeresults showed that the response was linearly proportional to the concentration of Hg²⁺in the range0-1.0×10^-6mol/L with a detection limit of1.2×10-8mol/L. The response mechanism was discussed by theexperiments of reversibility and IR spectra. Because of the fluorescent probe for Hg²⁺has been manyreported, the performance of the proposed probe RP was compared with some reported probes based onrhodamine B structural motif for Hg²⁺determination. RP was successfully applied to water samplesanalysis and intracellular Hg²⁺imaging in PC12cells.