The Synthesis Of Squaraine Dyes And Investigation Of Metal Ions Detection

This topic uses squaraine as the basic raw material,aniline derivatives and indole derivatives as nucleophiles.The corresponding squaraine dyes are obtained through dehydration and condensation reactions,and the corresponding squaraine dyes are obtained by nuclear magnetic resonance(¹H NMR and ¹³C NMR),Fourier Infrared(FT-IR)and other methods were used to characterize its molecular structure,and then the synthesized squaraine cyanine was used as a chemical sensor to identify the performance of metal ions.The detection effect of 2-(benzylthio)aniline squaraine(BAS)on metal ions was analyzed by UV absorption spectroscopy.The results show that 2-(benzylthio)aniline squaraine can efficiently and selectively detect metals.The ions Cu²⁺and Hg²⁺were used to study the complex ratio between 2-(benzylthio)aniline squaraine and metal ions using Job's plot working curve.In addition,because 2-(benzylthio)aniline squaraine has obvious color changes before and after chelation with Cu²⁺and Hg²⁺,Cu²⁺and Hg²⁺can be detected by naked eyes.In order to identify other heavy metal ions in the environment,a monosubstituted squaraine(BIO)was designed and synthesized.The analysis of ultraviolet-visible absorption spectrum and fluorescence emission spectrum shows that BIO can effectively detect metal ions Fe³⁺and Cu²⁺.Then,according to the Job's plot work curve,the complex ratio of BIO to Fe³⁺and Cu²⁺was analyzed.The complex ratios of BIO-Fe³⁺and BIO-Cu²⁺were both 1:1.Because BIO has obvious color changes before and after recognition of Fe³⁺and Cu²⁺,Fe³⁺and Cu²⁺can be detected intuitively with the naked eye.In addition,according to the changes in the ultraviolet absorption spectrum of Fe³⁺and Cu²⁺before and after BIO recognizes it,it is designed as a molecular logic gate circuit capable of storing and erasing.An asymmetric squaraine(BIOT)was synthesized on the basis of monosubstituted squaraine.UV-visible absorption spectroscopy analysis shows that BIOT can effectively detect metal ions Fe³⁺and Cu²⁺.In order to study the sensitivity and timeliness of BIOT,the detection limit experiment and kinetic experiment were designed and operated.At the same time,the probe can respectively recognize the metal ions Fe³⁺and Cu²⁺in the mixed solution of ethanol and water,and the solution has obvious color changes before and after the recognition,and can directly detect the presence of Fe³⁺and Cu²⁺with the naked eye.According to this phenomenon,it is made into test strips,which makes the detection process more convenient and environmentally friendly.In order to further improve the selectivity of the probe to identify metal ions,the introduction of phenolic resin and squaraine dye dehydration condensation to form a squaraine resin polymer.Therefore,the compound contains a large steric hindrance,so it can improve the selectivity of recognizing metal ions.According to the actual theory,a new type of carboxyindole squaraine resin(HOC)was successfully synthesized.The UV-visible absorption spectrum can be analyzed to show that HOC can effectively identify Fe³⁺and Cu²⁺.In order to explore the sensitivity of the probe,a detection limit experiment was designed.The detection limit of HOC-Fe³⁺is 8.87×10^-7M,and the detection limit of HOC-Cu²⁺is3.13×10^-6 M.At the same time,it is found that HOC has strong timeliness in identifying metal ions through kinetic experiments.In order to understand the ability of various squaraine dyes to recognize the corresponding ions,the anti-interference ability and the interaction mechanism with metal ions,ion titration experiments,response time experiments,detection limit experiments,ion competition experiments,infrared Detection experiments,test paper experiments,etc.were implemented to further study the recognition effect of each squaraine dye to recognize the corresponding metal ion.