Synthesisand Property Of Fluorescent Chemodosimetric Probes Based On Cyanine Dyes

As with advantages of high selectivity, high sensitivity, real-time monitoring, easy operation and low cost, fluorescent probes have very extensive application in the field of cations and anions monitoring. And because of its unique optical properties, cyanine dyes are widely used in the design of the fluorescent probes, whose structure modification can improve the stability and solubility, which will make it better apply to fluorescent probes.As coumarin has a strong performance in fluorescent intensity, it was combined with3-ethyl-2-methylbenzo[d]thiazol-3-ium to design probe1for cyanide ion detection. With UV-vis absorption spectra and fluorescence emission spectra, we study the selectivity, sensitivity, response time of probe1for cyanide ion detection, and its mechanism has been confirmed by UV-visible absorption spectra, fluorescence emission spectrum and nuclear magnetic resonance spectra. In aqueous system, probe1can realize selective recognition to cyanide ion with the signal of blue shift in absorbance and emission ratio dual fluorescence changes. The stoichiometric ratio of probe1reacting with cyanide ion is1:1.The naphthalene ring was combined with indole to synthetize probe2a because of the conjugate structure of naphthalene ring, which will contribute to the fluorescence properties in probe2a, the naphthalene ring was also combined with3-ethyl-2-methylbenzo[d]thiazol-3-ium to synthetize probe2b. The introduction of new site allyl carbonate will speed up the reaction between probes and palladium, as the rupture fracture of ester bond is much easier than amide bond. The paper performed the spectral properties of probe2a and2b and explored the practical application in the environmental and biological systems, and the results and discussion are as follow,We study the selectivity, sensitivity, response time of probe2a detecting palladium by using fluorescence emission spectra, Probe2a is a fluorescent probe for palladium ions with high selectivity, highly sensitivity. The fluorescent emission spectra underwent a change from weak fluorescent intensity in the range from470nm to520nm to very strong fluorescent intensity at566nm. In ethanol and HEPES buffer solution, the detection limit of probe2a for palladium ion detection reaches2.29×10-7mol/L.We study the ion selectivity, sensitivity, response time of probe2b detecting palladium by using fluorescence emission spectra and UV-vis absorption spectra, and study the mechanism by using UV-vis absorption spectra and MALDI-TOF-MASS. The fluorescence emission spectra of probe2b underwent a change from510nm to566nm, and its fluorescent color changed from green to orange, which is a very good ratio fluorescent probe. In DMSO and HEPES buffer solution, the detection limit of probe2b for palladium ion detection is1.2×10-8mol. L-1, and the response time is only10minutes, the probe2b performs as a palladium sensor with high sensitivity and rapid detection. We using fluorescence emission spectrum to explore the application in biological systems and in environmental system of probe2b and found that probe2b can realize qualitative detection and quantitative detection for palladium ions in environmental and biological systems.