Novel Fluorescent Schiff-base Probes For Ions And Their Applications In Cellular Imaging

Chapter 1:The principle and influencing factors of molecular fluorescence,the composition,classification and response mechanism of fluorescent sensors are introduced.The classification and development prospect of Schiff base fluorescent probes are briefly outlined.Chapter 2:A novel fluorescent sensor 4'-hydroxy-3'-??4-antipyrineimino?methyl?-4-biphenylcarbonitrile?L?was prepared for the selective detection of Zn²⁺in aqueous ethanol medium and could clearly distinguish Zn²⁺from Cd²⁺.The fluorescence intensity of L at 507 nm was remarkably increased 54-fold after adding Zn²⁺ions.Naked eye color of the solution changed from colorless to pale yellow.Thus,sensor L behaves as a naked eye fluorescent“turn on”detector for Zn²⁺ions and the detection limit is 2.1×10^-7 M.The complex solution of L with Zn²⁺ions exhibited reversibility and the probe could be recycled for further use.The interaction of L with zinc ions was investigated using FTIR,¹H NMR and HRMS spectroscopy.Furthermore,L has been successfully applied for cell imaging studies.Chapter 3:A new and simple Schiff base?L?was synthesized starting from3-?benzothiazol-2-yl?-5-bromo-2-hydroxybenzaldehydeand2-pyridine hydrazide.L acts as an effective fluoromrtric chemosensor for Al³⁺detection in aqueous buffer solution.The detection limit is 31.2 nM,which is hundred fold lower than the WHO guideline?7.41?M?for drinking water.L has the ability to sense Al³⁺ion in human hepatoma carcinoma cells BEL-7402 by fluorescence confocal imaging.Chapter 4:A new Schiff base fluorescent probe L has been synthesized with3-?benzothiazol-2-yl?-5-bromo-2-hydroxybenzaldehydeand tris-?hydroxymethyl?aminoethane.In tris-HCl buffered DMSO-H₂O?1:1,v/v,pH=7.2?solution,L could effectively complex Cu²⁺at a molar ratio of 1:1,leading to a color change from yellow to green and significant fluorescence quenching at 528 nm.In addition,the formed L-Cu²⁺complex can be further used for S^2-detection by metal displacement.Upon addition of S^2-to the solution of L-Cu²⁺,the fluorescence of L was recovered with high selectivity.The detection limits for Cu²⁺and S^2-were 2.32×10^-8 M and 6.57×10^-8 M,respectively.A test strip of probe L has been fabricated and used to detect Cu²⁺.In addition,L can be used to detect endogenous Cu²⁺and S^2-in living cells.