Novel Colorimetric And Fluorescent Probes For The Detection Of CN~-

Chapter 1:The composition and design principles of fluorescent probe are introduced.And the research progress in recent years on the development of fluorescence sensors for CN^-recognition is reviewed.Chapter 2:A novel Schiff Base probe L₁ for the dual sensing of Zn²⁺and CN^-has been synthesized and characterized.In EtOH-H₂O?3:2,v/v;HEPES,pH7.4?,L₁ selectively binds Zn²⁺to form a 1:1 ligand/metal complex.Addition of Zn²⁺to the solution of L₁ resulted in a blue shift???=15 nm?with a pronounced fluorescence enhancement at 468 nm,while there was no enhancement in presence of other metal ions,especially Cd²⁺.The limit of detection was measured to be 3.65×10^-8 M.Cell imaging studies demonstrate that this sensor is capable of sensing Zn²⁺in living cells.In DMSO-H₂O?3:7 v/v?medium,addition of cyanide ion to L₁ lead to deprotonation of the phenol hydrogen,resulting in a color change from colorless to pale yellow and a significant fluorescence enhancement at 510 nm.The probe exhibits high selectivity and sensitivity for CN^-ion and the detection limit were found to be 5.75×10^-7M.Finally,the use of a test strip of probe L₁to detect cyanide was reported.Chapter 3:Anintramolecularchargetransfer?ICT?and aggregation-induced emission?AIE?based chemodosimeter?L₂?derived from naphthopyran and malononitrile was developed for the selective sensing of CN^-in buffered aqueous medium.Sensor L₂ demonstrated the presence of CN^-by both fluorescence quenching and an instantaneous color change of solution from orange to colorless.The proposed mechanism is the addition of CN^-on the?-position of the dicyano-vinyl group of L₂,and consequently breaking the conjugation,which ultimately affect the ICT.The sensor exhibits high selectivity and sensitivity for CN^-ion and the detection limit were found to be 4.27×10^-7 M.Finally,the use of a test strip of probe L₂ to detect cyanide was reported.Chapter 4:A naphthopyran derivatives?L₃?has been developed as a novel colorimetric and ratiometric fluorescent sensor for cyanide detection in aqueous solution.Upon addition of cyanide,L₃ displayed a fluorescence ratiometric response with a blue shift???=171 nm?and a remarkable color change from purple to colorless within 90 s.The detection of cyanide was performed via the nucleophilic addition of cyanide anion to the benzindole group of the sensor,which resulted in the block of the intramolecular charge transfer?ICT?.Furthermore,competitive anions did not showed any significant changes both in color and emission intensity ratio(I₅₂₅/I₆₈₀),indicating the high selectivity of the sensor to CN^-.The sensor displayed high sensitivity to CN^-and the detection limit was calculated to be 7.56×10^-7 M,which is much lower than the WHO cyanide standard in drinking water?1.9?M?.