The Synthesis Of Oxazole/imidazole-phenazine And Its Research On Ion Recognition Performance

With the continuous development of chemical industry,the accumulation of toxic ions is gradually increased in water system.To identify a specific ion qualitatively and quantitatively in aqueous systems has attracted more attention of scientists.According to the reported literatures of the ion identification,with the experimental equipment continuously updated,the recognition methods have evolved from atomic absorption spectroscopy,inductively coupled plasma mass spectrometry and others to colorimetric and fluorescence identification methods now.Compared with the colorimetric and fluorescent recognition,other methods are highly specialized,difficultly operated and costly,which limited their application in field testing.At the same time,with the rapid development of supramolecular chemistry,researchers have made many great achievements in the field of host-guest recognition.Many recognition agents from heterocyclic compound as a precursor have been widely synthesized.As a typical representative of heterocyclic compounds,phenazine and its derivatives are favored by researchers in recognition due to its stable optical natures,easily to form ?-? stacking and strong fluorescence properties.Based on this,we design and synthesize different recognition objects in this thesis,which can specifically identify a specific kind of ions in aqueous systems.Chapter One: The application of heterocyclic compounds in the recognition of anions and cations.This part mainly introduces the research history and current status of supramolecular chemistry,and focuses on the application of heterocyclic compounds in the recognition of anions and cations.Chapter Two: Study on the UV-vis and Fluorescence Properties of 2-Phenyl-1H-Imidazolophenazine(ZH)in Cation Recognition.We designed and synthesized a new compound(ZH),which phenazine as fluorescent group and imidazole ring as recognition site.The compound formed self-assembly system through ?-? stacking and intermolecular hydrogen bonding in the semi-aqueous system,causing the compound solution had yellow fluorescence.The self-assembly system was broken with the addition of Ag+ to the solution,resulted that the fluorescence quenched and the solution color became light pink.The solution of Na I was added to the solution of ZH + Ag+,the fluorescence was turned on,and then Ag+ was added to the mixture solution,the fluorescence was quenched.This ON-OFF type can be cycled more than four times.The facts indicated that the recognition process was a reversible process and the sensor could be used as a multi-employ identification tool.The test paper of ZH greatly improved the practical application performance of this sensor,which was favorable for the sensor molecule to be widely used.Chapter Three: Two-channel identification of Cyanide ions(CN-)in Phenazine derivatives based on Supramolecular Self-Assembly.This section synthesized imidazo-phenazine derivative(ZH)which could highly selective recognition CN-in aqueous systems.It can be seen from the single crystal structure that the nitrogen atom of the imidazole forms an intermolecular hydrogen bond with the-NH of the imidazole ring in another molecule and the molecules are stacked by ?-? interaction.Intermolecular hydrogen bonds and ?-? stacking were together constituted the self-assembly system of ZH,which made the solution presented yellow color and had strong yellow fluorescence.Upon the addition of CN-,the self-assembly system was destroyed with the deprotonation occurred,which resulted the solution became orange-red color and the fluorescence quenched.We also found that the color and fluorescence was no less with this sensor by the addition of H+ to the solution of ZH-CN-.And then added the CN-to the mixture solution,which caused the color turned into orange-red and the fluorescence was quenched.Meanwhile,this process can be recycled more than five times and almost no loss of fluorescence intensity,which indicated that ZH can be used repeatedly.This test also greatly improved the economy applicability of the sensor molecule.The lower detection limits of UV and fluorescence(5.0 × 10-8 and 7.0×10-8 mol/L,respectively)made ZH a considerable advantage in low-concentration assays.Dropping a variety of common anions to the test papers of ZH,the obvious color and fluorescence contrast greatly improving the field-test application of ZH.Chapter Four: Study on the Fluorescence Properties of 2-Mercaptooxazolophenazine(TZ)Selective Cations.A new fluorescent sensor(TZ)with phenazine group as luminant and thiol as recognition group was synthesized,which could detect Hg2+ transiently in aqueous system.The sensor had two isomers of thionone and thiol.According to the experiment data of the IR spectra and NMR spectra,it can be speculated that the predominant form of solution and solid were thionone and thiol structure respectively.In p H = 7.2 HEPES buffer solution,TZ could occure the deprotonation proess.With the addition of Hg2+ to this solution,it will coordinate with the oxazole nitrogen atom and the thiol group,which caused the fluorescence changed from yellow to light blue.The lower naked eyes minimum detection limit(10-5 mol/L)will greatly improve the application capacity of TZ in the actual detection.At the same time,we also found that TZ could detect Hg2+ in the solution of p H = 2-8.In addition,test strips of TZ had been made that can be used as a simple tool to identify Hg2+,which will be a small breakthrough in field testing.Chapter Five: Study on the Fluorescence Properties of 2-Mercaptoimidazophenazine(CW)Selective Recognition Cations.We synthesized a sensor molecule(CW)containing two binding site(imidazolane and thione group),which could quickly detect Hg2+ in the water-bearing system.In the mixture solution of DMSO and H2O(9:1,v: v,buffered with HEPES solution,p H = 7.2),through the deprotonation and the intramolecular charge transfer(ICT),which induced a nitrogen atom of imidazole ring and sulfur atom are separately with a negative charge,made the sensor became a typical into imidazole-thiol structure.With the addition of Hg2+ to the solution,Hg2+ combined with the nitrogen atom and sulfur atom,which made the fluorescence changed from yellow to pale red.We also found that the naked eyes minimum detection limit was 10-5 mol/L under the 365 nm Uv-lamp,which greatly promote the application of CW.At the same time,a test paper containing the CW has been made to provide portable tools for real-time detection.