Preparation Of Water-soluble Perylene Diimide Dyes And Its Application Research In F^-,S^2- Fluorescence Detection

As common anions,fluoride and sulfide ions not only exist widely in the environment,but also participate in a variety of physiological activities in organisms.Within a certain concentration range,they are beneficial to the human body,and after a certain concentration,it will threaten human health and even cause death.Therefore,efficient detection of fluoride and sulfide ions is of great significance for ensuring environmental safety and human health.Compared with traditional detection methods,fluorescence analysis has the advantages of fast,sensitive and convenient,and has gradually become a hot spot for analysis in recent years.At present,most fluorescence detection methods for anions have the disadvantages of complicated preparation of fluorescent materials,high temperature synthesis,poor specificity,and detection in organic/mixed solvents.In response to the above problems,we use perylene diimide derivatives as the chromophore,which have the advantages of easy modification,high molar extinction coefficient and fluorescence quantum yield,excellent chemical and photothermal stability.After being modified with suitable metal ion ligands,perylene diimide derivatives and specific metal ions formed water-soluble supramolecular aggregates,which served as fluorescent probes sensing system.The"Metal replacement method"was used to achieve rapid and accurate detection of fluoride and sulfide ions in aqueous solutions.This method takes advantage of the high affinity between metal ions and anions.Metal ions were used as specific recognition sites,and perylene diimide derivatives were used as chromophores,thereby avoiding the complicated design and synthesis of recognition sites.The specific content is as follows:（1）Utilize the strong binding ability between aluminum ion and fluoride ion and the good coordination ability of carboxyl group on glutamic acid.The perylene diimide derivative（PDI-Glu）functionalized with glutamic acid was synthesized through the"one-step method",which gave the perylene diimide the ability to coordinate with metal ions,and increase the water solubility of perylene diimide with excellent optical properties.After complexing with aluminum ions,PDI-Glu/Al³⁺supramolecular aggregates were formed as an"turn on"fluorescent probe for the detection of fluoride ions.The sensing performance and mechanism of the PDI-Glu/Al³⁺probes were studied by absorption and emission spectroscopy.The presence of fluoride ions would trigger the de-aggregation of PDI-Glu/Al³⁺aggregates and lead to a significant increase in the fluorescence intensity of PDI-Glu/Al³⁺.The detection limit is 0.24μmol/L,the linear range is 0.4 to 42μmol/L,the visual detection limit is 8μmol/L,and the system showed good specificity.It has been verified that this experiment can detect fluoride ions in toothpaste and tap water samples with excellent precision and recovery.（2）For the detection of sulfide ions,the histidine modified perylene diimide derivative（PDI-His）was synthesized by taking advantage of histidine’s excellent water solubility and good metal ion coordination ability.A water-soluble PDI-His/Cd²⁺supramolecular aggregate was prepared by coordinating with cadmium ions.Thus,a fluorescence-enhanced probe of sulfide ions was obtained.The analysis of the mechanism shows that the presence of sulfide ions would induce the de-aggregation of supramolecular aggregates,and the re-dissociation of PDI-His monomer would lead to a significant increase in fluorescence intensity.The probe has the characteristics of simple synthesis,convenient preparation and high detection sensitivity,and can be used to specifically identify sulfide ions.The detection limit is0.41μmol/L,and the linear range is 5-40μmol/L.Finally,sulfide ions were identified in actual samples of spinach,cabbage,chrysanthemum and MSG.The accuracy of this method was verified by iodometry.