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Design, Synthesis and Properties of Copper Ion Probes Based on Coumarin and Rhodamine

Author: ZengYang
Tutor: LiJunBo
School: Wuhan Institute of Technology
Course: Chemical processes
Keywords: coumarin rhodamine copper ion fluorescence probe colorimetric sensor
CLC: O626.2
Type: Master's thesis
Year: 2012
Downloads: 97
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Abstract

Copper ion is one of the indispensable trace elements which maintain thenormal life activities of organisms. Although its content is low, it plays a veryimportant role. When the copper ion concentration is out of the required range,the normal activities of life system would be disrupted and the cells would getpoisoning, which would cause severe copper metabolic disorders. Afterhaving water or food contaminated by copper ion, people will get someincurable diseases due to the high content of copper ion in their body.Therefore, it is particularly important to detect copper ion both in naturalenvironment and organism.In recent years, as commonly used dyes, the rhodamines and coumarinshave aroused wide concern because of its unique photochemistry andphotophysics properties. Rhodamine fluorophore has become a research hotspot with its advantages of good water solubility, long excitation wavelength,non-toxicity and so on. Coumarin compounds have high fluorescencequantum yield, long Stokes shift, good photostability and some otheradvantages. They are often used as separate light-emitting dyes and energytransfer donors as well. Thus, design and synthesis of novel coumarin andrhodamine fluorescent compounds are of significance.In this thesis, a general introduction to the research progress on coumarinand rhodamine-based fluorescent compounds and probes was presented andmany their novel fluorescent functional molecules are researched anddeveloped. The main contributions are listed as follows.A novel reactive coumarin-based fluorescence-enhancement probe wasdesigned and synthesized by modifying the position3and7. The probe Lcould be oxidized to coumarin6by copper ion, which soared the fluorescenceintensity while other metal ions and some common oxides such as H2O2,TBHP, NaClO had little influence. Thus, the oxidation mechanism was primarily studied. Shown through the data of the UV-vis spectrum andfluorescence spectrum, probe L could detect copper ion selectively withoutany interference with other metal ions. Furthermore, the detection limit ofcopper ion was as low as5.82×10-8M.Two molecules of rhodamine hydrazide were linked by2-hydroxy-5-methylisophthalaldehyde. Thus a novel rhodamine-basedcolorimetric probe Q was synthesized. The detection property for copper ionwas studied in Tris-HCl/CH3CN(v: v,1:1) solution and on the prepared testpaper, respectively. The absorption of probe Q at554nm enhanced as theaddition of Cu2+, which represented that the probe could selectively detectCu2+in the solution system and that could be observed by naked eyes. Todevelop the application of probe Q, the preparation of test paper based on theprobe showed that Cu2+could turn the paper into red in aqueous solution. Thenaked eye detection limit was1×10-4M.And then coumarin and rhodamine fluorophores were linked by C=Nbond, so that rhodamine-coumarin derivative probe was designed andsynthesized. Through the IR spectra analysis, the combining way and actionmechanism was studied. As a colorimetric sensor of Cu2+, the prominentadvantage of such a double chromophore probe is that the UV absorptionspectra got a very big change after chelating with Cu2+in mixed acetonitrileand water solution. Two redshift absorption peaks turned up, and one of themis apart from the original absorption peak108nm. The wavelengths of all ofthem are located in the visible range, so it can be distinguished with nakedeyes.As the position3,7and8of coumarin was introduced some otherfunctional groups, a novel fluorescence quenching probe was designed andsynthesized. We studied its selective ability as well as combining method. It isa high selective and sensitive probe of Cu2+with high fluorescence quenchingrate.

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