The Synthesis And Spectral Properties Of Heavy Metal Fluorescent Probe Based On Skeleton Of The Indole And Indole Derivatives

With the accelerated process of industrialization of human society,environmental pollution has become an increasingly urgent problem to be solved.Heavy metal ions are one of the main environmental pollution sources with slow degradation and great toxicity.Therefore,the analysis and detection of these ions are the first task in the process of pollution control.The traditional analysis methods of heavy metal ions often invovle expensive analytical instruments and need more complicated procedures,which increases the cost of operation and maintenance.So it is difficult to meet the need of more and more complicated and changeable actual detection.As a new analysis method of heavy metal ion,the organic molecule fluorescence probes have some advantages such as low cost and convenient operation,meanwhile,they show satisfactory repeatability,sensitivity and specificity.In addition,their optical signal can be detected in situ without the influence of electromagnetic field.In recent years,they have been widely used in environmental analysis,clinical diagnosis,clinical diagnosis,cell dyeing,biomolecular labeling and other applications.In this paper,We firstly reviewed the basic theory of fluorescent probes,the design idea,the mechanism of fluorescence control and the research progress of the heavy metal fluorescent probes currenttly.On the basis of extensive investigation,we chose the heterocyclic indoles which are low toxic,cheap and widely existed in the organism as core of the synthetic work.In the experimental part,a series of heavy metal fluorescent probes based on the indole derivatives skeleton have been synthesized and three systems have been carried out as follows:(1)We designed and synthesized a molecular L1 based on the isatin-rhodamine framework.With the indoles as raw material,a high oxidation state derivative was obtained by mild and efficient oxidation under the iodine reagent/DMSO system developed by our group.The rhodamine hydrazide was prepared by the reaction of hydrazine hydrate in alcohols with rhodamine-B.At last the acid catalyzed reaction of the isatins with the rhodamine hydrazine offers the target products.Through a series of fluorescence properties tests,it is found that L1 is a molecular fluorescence probe with specific recognition of mercury ions.(2)We designed and synthesized three types of moleculars L2,L3,L4 based on indole-coumarin skeleton.With salicylaldehyde as raw material,the modified coumarin fluorophore was constructed by the synthetic method of diethyl malonate,then a one pot reaction including constantly acylation and hydrazinylation were conducted and finally,the nitrogen heterocyclic products such as pyrrole,pyridine and indole were coupled with modified coumarin hydrazine in the form of Schiff base.Through a series of fluorescence performance tests,it is found that L2 has better performance than L3 and L4,which is a molecular fluorescence probe with good response to chromium ions.(3)We designed and synthesized a chroamanone skeleton molecule L5,which is structurally reversible and can be decomposed to three isatin molecules.Isatin was transformed to chroamanone firstly by the oxidation through concentrated sulfuric acid/hydrogen peroxide and then condensed with the other molecule of isatin.After the hydrazine reaction,the target product was obtained by condensation with the other molecule of N-benzyl isatin.Through a series of fluorescence performance tests,it is found that L5 is a molecular fluorescence probe with good response to lead ions.