Synthesis And Properties Of Cu²⁺ Spectral Probes Based On Salicylaldehyde Schiff Base

Copper(Cu²⁺)widely exists in nature,and it is indispensable to the human body in trace amounts.It plays a crucial role in many physiological processes.However,unregulated amount either an excess or deficiency may exacerbate deterioration of the vital organs and trigger the progression of complications endangering human health.Therefore,it is very meaningful to develop a simple,rapid and sensitive detection of Cu²⁺.In view of the advantages of the simple operation,low cost,high selectivity and sensitivity of spectral probes,in this work,we designed and synthesized two types of novel good properities probes based on salicylaldehyde Schiff base for the detection of Cu²⁺,which are hydrazone of Schiff base as colorimetric probes and double Schiff base as fluorescent probe.Their structures were characterized by NMR,FTIR,MS,and optical properties were studied by UV-vis absorption spectroscopy and fluorescence spectroscopy.The simple,quick and sensitive methods were developed for the detecting of Cu²⁺.Moreover,the binding mechanisms of probe with Cu²⁺ were discussed,and then the as-prepared probes were applied for Cu²⁺ detection in drinking water and biological imaging.Chapter 1:We summarized the composition of spectral probe,the classification and properties of salicylaldehyde Schiff base.And we reviewed the recognition mechanism of spectral probes and the research progress of salicylaldehyde Schiff base as spectral probe for the detection of Cu²⁺.Chapter 2:A novel salicylicaldehyde derivative 5-bromosalicylicaldehyde fluorescein hydrazone?BSFH?is synthesized by the condensation reaction of 5-bromosalicylicaldehyde with fluorescein hydrazide.BSFH are characterized by nuclear magnetic resonance?NMR?spectroscopy,mass spectrometry?MS?,elemental analysis.BSFH has almost no absorption in visible region.However,the presence of Cu²⁺ results in a rapid color change of the solution from colorless to yellow along with a very obvious new absorption band appeared at 496 nm in the UV-vis absorption spectra of BSFH.The absorbance of BSFH at 496 nm is increased gradually with the increase of Cu²⁺.Experimental results indicate that the chemical stoichiometric ratio between the BSFH and Cu²⁺ is 1:1,the linear range of detecting Cu²⁺ is 1.0 10 ?mol/L and the detection limit is 0.30 ?mol/L.The relative standard deviation?R.S.D.?is 2.5 %.Other metal ions do not show any interference on the determination of Cu²⁺.BSFH shows highly selective and sensitive to Cu²⁺ in the aqueous solution.Therefore,BSFH can provide a simple,rapid and sensitive method for the detection of Cu²⁺ in the aqueous media.Chapter 3:A new colorimetric probe 5-chlorosalicylaldehyde fluorescein hydrazone?CSFH?is synthesized and characterized by 1HNMR,13 CNMR,MS,elemental analysis and X-ray single crystal diffraction.The absorption and fluorescence spectra of the reaction of CSFH with Cu²⁺ are studied.In the presence of copper???ion,an obvious new absorption band appeares at 495 nm in the absorption spectra of CSFH and a rapid color change of the CSFH solution from colorless to yellow together.This change is attributed to the spirocycle form of CSFH opened via coordination with Cu²⁺ in a 1:1 stoichiometric ratio.The association constant of CSFH and Cu²⁺ is determined as 6.85×105 L/mol.The absorbance intensity and the color of CSFH solution increase gradually with the increase of Cu²⁺ concentration.The as-prepared CSFH is employed as a colorimetric probe for the detection of Cu²⁺ via naked-eye and UV-vis spectrophotometer.Common metal ions do not show any interference on the determination of Cu²⁺.The linear ranges for Cu²⁺ detection are 0.8 14 ?mol/L and 1.0 14 ?mol/L with the detection limits 0.25 ?mol/L and 1.0 ?mol/L of Cu²⁺ using the UV-Vis changes and the visual color changes by the naked eye respectively.The proposed method is successfully applied to the determination of Cu²⁺ in drinking water sample and the recovery is 96 106 %.The relative standard deviation?RSD?is 2.1 %.Chapter 4:A double Schiff base based on salicylaldehyde derivative,2-hydroxynaphthylsalicylaldehyde?CSNH?,is facile synthesized and characterized by NMR,MS,elemental analysis.CSNH is insoluble in water,but is soluble in DMSO.CSNH is nonemissive in DMSO solvent which may be caused by active intramolecular rotations of the phenyl and naphthyl ring at the CSNH end group.However,the strong aggregation-induced emission?AIE?enhancement occurres in H2O/DMSO?dimethyl sulfoxide?mixed,which resulted from a restriction of free intramolecular rotation due to the combined effects of intramolecular hydrogen bond formation,ordered molecular stacking with aggregate formation and the blocking of the nonradiative decay of excited molecules through formation of aggregate.The fluorescence intensity of CSNH in H2O/DMSO?v/v,8:2?is about 90-fold than that in pure DMSO.And the CSNH nanoparticles with a bright yellow fluorescence are formed in H2O/DMSO?v/v,8:2?.The morphology of clavate and size of the CSNH nanoparticles about 50 nm is observed by TEM image.Moreover,CSNH has very litter cytotoxicity to cells and good biocompatibility.CSNH is applied in fluorescence imaging in live Siha cells.Chapter 5:A fluorescent method for the detection of Cu²⁺ based on AIE effect of CSNH in H2O/DMSO?v/v,8:2?mixture solvent is reported.CSNH in H2O/DMSO?v/v,8:2?emits bright yellow fluorescence,but the fluorescent intensity of CSFH solution decreases gradually with the increase of Cu²⁺ concentration,which is due to the solubility of CSNH increased by the combination of Cu²⁺.The chemical stoichiometric ratio between the CSNH and Cu²⁺ was 1:1,and their association constant is 6.31×104 L/mol.The linear range of detecting Cu²⁺ concentration is 5³00 ?mol/L and the detection limit is 1.5 ?mol/L.The relative standard deviation?RSD?is 2.7 %.Common metal ions do not show any interference on the determination of Cu²⁺.CSNH can be a good fluorescent probe for the detection of Cu²⁺ and has been successfully applied for the imaging of Cu²⁺ in living cells.