Design,Synthesis And Recognition Of Perfluorinated Contaminants Of Dipyrrorole Schiff Base Derivatives

Perfluorinated compounds(（Perfluorinated compounds,PFCs）have many properties such as hydrophobic,oleophobic,good surface activity and strong acid and alkali resistance due to their unique structure.Therefore,it is widely used in chromium plating,fire foam,surfactant（insecticide,cosmetics,etc.）,polymer additives,food packaging and textile production and many other industrial production and living consumption fields.Because of its special properties,it is difficult to be degraded and is widely distributed with water and atmosphere,and eventually enters the human body through the food chain,producing different toxicity to different organs and systems of the human body.In order to prevent further distribution of pollutants,there are a variety of sample pretreatment technologies and detection methods,but the detection technology is mostly based on mass spectrometer and chromatographic instrument,which is not convenient and has limitations in practical operation,so a simple and sensitive fluorescent probe to identify and detect pollutants is necessary.13 intermediates and 6 target compounds were designed and synthesized from propionaldehyde,1-nitropropane,methyl formate and glycine ethyl ester hydrochloride.The probes were characterized by ¹H-NMR,¹³C-NMR,UV-vis and HR-MS,and the recognition performance of these probes to perfluorocarboxylic acid was studied by UV-visible absorption spectroscopy and fluorescence spectroscopy.In addition,the stoichiometric ratio of probes to perfluorocarboxylic acid was measured by ultraviolet titration experiment and Job’s curve.The anti-interference of the probe was tested by UV-visible absorption spectrometry and fluorescence spectrometry.The UV-vis absorption spectras showed that the maximum absorption peaks of the six probs were redshifted after the addition of perfluorocarboxylic acids.Fluorescence spectras showed that the intensity of their emission peaks decreased significantly after the addition of perfluorocarboxylic acids,and there were visible fluorescence changes in acetonitrile solution.The binding ratio of the probesⅠ-1、Ⅰ-2、Ⅰ-3、Ⅰ-4 with perfluorocarboxylic acid were 1:4;1:3;1:3;1:2 by ultraviolet titration experiments and Job’s curves and the binding mechanism of probeⅠ-1 to perfluorocarboxylic acid was also speculated.It was found that probeⅠ-3 had the best anti-interference by the anti-interference study of probesⅠ-1,Ⅰ-3andⅠ-4.In this paper,a series of probes with pyridine or phenyl-bridged bispyrrole as the skeleton were synthesized for the first time,which were accompanied by visible fluorescence color changes while recognizing perfluorocarboxylic acids.It was found that when there are more than 4 interacting fluorocarbon chains,there is a stacking phenomenon between them.This study provides a new idea for the development of methods and techniques for rapid and accurate detection of PFCs in the future.