Synthesis And Properties Study Of Copper(Ⅱ) Probes Based On Schiff Base Derivative

Schiff bases are widely used in various fields because of its special compounds containing a C=N bond.In the medicine,Schiff bases have significant efficacy on the antivirus,sterilization and antitumor,thus they have been used in clinical application.The Schiff base compounds are also been used in corrosion resistance and catalysis field.Especially in the analytical chemistry,the Schiff bases can coordinate with metal ions to form coordination complex because of the structural characteristic of the conjugated C=N bond.Fluorescence detection is one of the most common methods according to the change of original structure by chemical analysis method.Thus,Schiff bases compounds are always used to be the fluorescence probe to detect ions in the organism and environment.Fluorescent molecular probes are widely used in modern science such as medicine,environmental science and bioscience because of the high-speed,high sensibility,high sensitivity even naked eye recognition.Therefore,it is significant and meaningful to design and synthesis of the probe based on Schiff base.In this paper,five probes based on Schiff base were designed and synthesized using 4-nitrobenzene-1,2-diamine,2-hydroxy-1-naphthaldehyde,9-ethyl-9Hcarbazole-3-carbaldehyde,2-oxo-2H-chromene-7-carbaldehyde and 6-bromo-1H,3Hbenzo[de]isochromene-1,3-dione as the raw materials.The structures of the probes were characterized by 1H NMR,13 C NMR,HRMS and IR.Among of them,the probes C₁、C₂、C₃ were synthesized for the first time.Subsequently,the probes were applied to the detection of the ions.All of the five probes C₁-C₅ can recognize Cu²⁺,and the probes C₁、C₃、C₄ and C₅ exhibit highly selective and sensitive recognition towards Cu²⁺ by ultraviolet-visible absorption spectra and fluorescence spectra.Moreover,the probe C₅ can be used for the naked-eye recognition for Cu²⁺.The pH detection of probes C₄ and C₅ was conducted.The results showed that they have the ability to resist acid and alkali,which provided an opportunity for the detection of ions in the complex environment.Further study indicated that the probes C₁-C₅ can detect Cu²⁺ without suffering any interference from other metal ions.The analysis of the Benesi-Hildebrand equation indicated that the formation of the 1:1 complex of between the probes and Cu²⁺.The association constant Ka=5.47×106M-1 and the lowest detectable limit of 1.43×10-4mol/L for probe C₁.The association constant Ka=2.27×106M-1 and the lowest detectable limit of 7.74×10-4mol/L for probe C₂.The association constant Ka=1.64×106M-1 and the lowest detectable limit of 4.78×10-4mol/L mol/L for probe C₃.The association constant Ka=2.73×105M-1 and the lowest detectable limit of 5.98×10-6mol/L for probe C₄.The association constant Ka=6.31×105M-1 and the lowest detectable limit of 4.02×10-6mol/L for probe C₅.