| Chapter 1:The design principle of fluorescent sensors based on the photoinduced electron transfer (PET) is introduced. And the latest research progress in recent years on the development of PET fluorescent sensors for determination of cations is reviewed.Chapter 2:A new acridine fluoroionophore AI containing two water soluble iminodiacetic acid groups was synthesized according to the PET format. And its fluorescent sensing behavior towards metal ions was investigated. When Zn2+ ion was added to the aqueous solution of AI at neutral pH, the fluorescence intensity of the band was enhanced at 454nm. The selective switch-on fluorescence response of AI to Zn2+ makes it suitable for determination of Zn2+ in aqueous solution. The detection limit is 5.4×10-/M.Chapter 3:A new acridine fluoroionophore containing two diethanolamine ligands,4,5-Bis(N,N-di (2-hydroxyethyl)iminomethyl) acridine(BHIA), was designed and synthesized based on the fluorophore-spacer-receptor format. And its fluorescent sensing behavior toward metal ions was investigated in buffered aqueous media. The presence of Cd2+ induces the formation of a 1:1 ligand/metal complex at neutral pH, which exhibits enhanced emission at 454 nm. The fluorescence intensity is linear with the Cd2+concentration in the range of 1.0×10-6 to 3.0×10-5 M (R= 0.9967). The effect of foreign ions on the intensity of BHIA showed a low interference response towards other metal ions. The selective switch-on fluorescence response of BHIA to Cd2+ makes it suitable for determination of Cd2+ in aqueous solution. The detection limit is 1.3×10-7 M. Moreover, the results indicated that BHIA was a reversible chemosensor for Cd2+, which makes it attractive for sensing applications. Chapter 4:Using N-methylpiprazine as well as mercaptoacetic acid as ligands, two new acridine fluoroionophores were synthesized and characterized. |
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