Fluorescent Probes Based On Heptamethine Cyanine Derivatives:Design,Synthesis And Their Application For Anions Detection

Cyanide is a chemical raw material widely used in many fields and is extremely important in industry and agricuture.However,cyanide anion（CN^-）is toxic.With the exposure to industrial wastes containing CN^-,the environment and human health are heavily threatened.Hypochlorous acid is widely used as a disinfectant,antibacterial agent and bleaching agent in daily life.At the same time,hypochlorous acid is also an important reactive oxygen species（ROS）,which plays an important role in various physiological and pathological processes.However,excessive hypochlorous acid is harmful to the human body and can cause a variety of diseases.It is important to rapidly and effectively detect of CN^–and ClO^–.In this dissertation,three kinds of fluorescent probes based on heptamethine cyanine derivatives were designed and synthesized,which were utilized to recognize cyanide ions and hypochlorous acid quickly and efficiently.The detailed discription are as following:（1）Design and synthesis of carbazole-heptamethine cyanine based fluorescent probe Cz-Cy7 and its application in CN^–and ClO^–detection.Cz-Cy7 was synthesised by the Suzuki coupling reaction between parent dye M1 and 9-Phenylcarbazole-3-boronic acid,and the molecular structure was fully elucidated by ¹H NMR,¹³C NMR and MALDI-TOF mass spectroscopy.The detection performance of Cz-Cy7 towards CN^–and ClO^–was investigated by UV-Vis and fluorescence spectroscopy.The results showed that with the addition of CN^–,the absorbance and fluorescence emission intensity of the probe Cz-Cy7 gradually decreased accompanied by a new absorption peak appeared in the short-wave region,and the color of the solution changed from green to yellow.Common anions caused no significant interference with the CN^–detection and the minimum detection limit was founded to be 0.13μM;Moreover,the absorbance and emission intensity of the probe Cz-Cy7 gradually decreased with the addition of ClO^–,and the color of the solution changed from green to colorless.Other active oxygen species lead to negligible interference with the ClO^–detection,and the detection limit was calculated to be 0.05μM.Additionally,the probe was successfully applied to detect CN^–and ClO^–on test strips.（2）Design and synthesis of a novel fluorescent probe Cz-S-Cy7 based on N-phenyl-3-carbazole-heptamethine cyanine conjugate and of its application in CN^–and ClO^–detection.Cz-S-Cy7 was prepared by the Suzuki coupling reaction between sulfonic group substituted cyanine M2 and 9-Phenylcarbazole-3-boronic acid,and the molecular structure was fully verified by ¹H NMR,¹³C NMR and MALDI-TOF mass spectroscopy.The detection performance of Cz-S-Cy7 towards CN^–and ClO^–was investigated by UV-Vis and fluorescence spectroscopy.The results exhibited that the absorbance and fluorescence emission intensity of the probe Cz-S-Cy7 in DMF/H₂O gradually decreased with the occurance of a new absorption peak in the short-wave region,and the color of the solution changed from green to bright yellow.Common anions caused no obvious interference with the CN^–detection and the minimal detection limit was down to 0.09μM;Similarly,the absorbance and emission intensity of the probe Cz-S-Cy7 in CH3CN/H2O gradually decreased and the color of the solution changed from green to colorless upon addition of NaClO.Other active oxygen species did not significantly interfere the detection of ClO^–and the minimal detection limit was lowed to 0.014μM.Additionally,the probe was successfully applied to detect CN^–and ClO^–in real water samples and on test strips.Compared with Cz-Cy7,the probe Cz-S-Cy7 displayed better performance on the detection of CN^–and ClO^–owing to its better water solubiliy.（3）Design and synthesis of water-soluble heptamethinecyanine fluorescent probe Cy7 and its HClO detection performance.The probe Cy7 with four solfonic groups was synthesized using 4-Hydrazinobenzenesulfonic acid,methyl isobutylketone,1,3-Propanesultone and cyclohexanone as reactants,and the molecular structure was fully verified by ¹H NMR、¹³C NMR and MALDI-TOF mass spectroscopy.The detection performance of Cy7 towards ClO^–was investigated by UV-Vis and fluorescence spectroscopy.The results showed that with the addition of NaClO,the absorbance and emission intensity of Cy7 decreased gradually and the common reactive oxygen species did not cause significantly interference.A good linear relationship between fluorescence intensity of Cy7 and the concentration of NaClO was observed.The minimal detection limit was 0.04μM according to the equation of LOD=3σ/S.The reaction mechanism of Cy7 towards hypochlorous acid was confirmed by MALDI-TOF mass spectrometry.It was also found that the probe Cy7 has great potential for portable and rapid detection of hypochlorous acid on real water samples and filter paper.