Synthesis And Properties Of Fluorinated Calix[4]arene Derivatives

Calixarenes are widely used in separation,chromatography,extraction,enzyme simulation,phase transfer catalysis,molecular recognition and pharmaceuticals due to their advantages of adjustable cavity size,easy functionalization,variable conformation and good stability.Traditional calixarenes have been unable to meet people's needs.Calixarene derivatization reactions are gradually developing.Calixarenes are introduced into functional groups to achieve properties that they did not have before,and calixarene derivatives are prepared.In recent years,the research of calixarene derivatization has focused on introducing functional groups into the upper and lower edges of calixarenes and introducing N,S,O atoms into the framework of calixarenes instead of methylene.In this paper,fluorinated calix[4]arene derivatives 1-3 were successfully synthesized.Trifluoromethyl phenyl,4-fluorophenyl and 3,5-bis-trifluoromethyl phenyl were introduced into the upper edge of calixarene.The conjugation unit increased and the conjugation effect enhanced.At the same time,strong electron-withdrawing groups such as fluorine atom and trifluoromethyl were introduced into the upper edge of calixarene.Derivatives 1-3 have applications in the field of ion recognition,and can be used as a new method to detect ions.The main research contents of this paper include the following parts:The intermediate of tetrabromocalix[4]arene was designed and synthesized.The first step is to synthesize p-tert-butylcalix[4]arene;the second step is to synthesize de-tert-butyl calix[4]arene;the third step is to synthesize ethoxycalix[4]arene;and the fourth step is to synthesize tetrabromocalix[4]arene.The structure of tetrabromocalix[4]arene was characterized by MS and¹HNMR.Designed and synthesized fluorinated calix[4]arene derivatives 1-3.Fluorinated calix[4]arene derivatives 1-3 were synthesized by Suzuki coupling reaction based on tetrabromocalix[4]arene and were introduced fluorine groups?-F,-CF₃?into the upper edge of calixarene.The structures of derivatives 1-3 were characterized by ¹HNMR,MS,FT-IR,UV-Vis spectra,fluorescence spectra and X-ray single crystal diffraction.At the same time,the single crystal of compounds 1-2 was obtained.Compounds 1-2 were conical conformation,and the conformational isomer of compound2 was 2',which was partial conical conformation.The ion recognition properties of fluorinated calix[4]arene derivatives 1-3 were studied by ultraviolet absorption spectra and fluorescence emission spectra.When copper ions were added,new absorption peaks appeared at 246 nm,237 nm and 246 nm for compounds 1-3 respectively,and the UV absorption intensity with several fold increase.The fluorescence emission intensity of compounds 1-3 decreased significantly,and the fluorescence quenching phenomenon was obvious.These results indicate that compounds 1-3 have selective recognition for copper ions.The anti-interference ability of fluorinated calix[4]arene derivatives 1-3 was studied by ultraviolet absorption spectra and fluorescence emission spectra.When copper ions coexist with other ions,the ultraviolet absorption spectra of compounds 1-3 are similar to those of compounds1-3 with only copper ions added.The maximum ultraviolet absorption intensity was significantly enhanced,and the existence of copper ion could be judged from the maximum absorption wavelength and absorption intensity.Other ions had no obvious interference effect.When the two ions coexist,the fluorescence emission intensity of compounds 1-3 also decreases significantly,and the quenching degree is similar to that of adding only copper ions.These results indicate that the presence of other metal ions has no significant effect on the recognition of copper ions.