Design,synthesis And Detection For Fe²⁺ And Glyphosate Of Fluorescence Probes Based On Oxanthene Structure

In the living system,some metal cations such as Fe²⁺/Fe³⁺,Cu²⁺,Zn²⁺etc are involved in a large number of physiological and pathological processes,which playcrucial role in the human life and health.In order to better understand their functions and influences,further elaborate their production,transportation and downstream functions,the development of detection methods with high selectivity and high sensitivity has become a research hot spot in the field of biological and environmental detection.In addition,the current food safety is also a hot topic of concern to the whole society.In particular,the development of detection technologies for pesticide residues on fruits and vegetables is the focus of current chemical analysis research.As a unique analytical detection technology,Fluorescence analysis method has lots of advantages,such as high sensitivity,high selectivity,non-invasion to biological samples,rapid real-time in-siti detection,and multiple signal output,and so on.Thus fluorescent probes are considered to be an important tool for the study and detection of physiological processes of the active species in living animals and living cells,and also have been widely used in the detection of biologically active molecules,anion and metal cation.However the fluorescent probes used in the relevant direction of pesticide detection are rare.In this thesis,with the core of new organic small molecule fluorphore,To design and synthesize a series of fluorescent probe molecules based on the rhodamine 110structure,Rhodol-HBT structure for the detection of Fe²⁺,Cu²⁺metal ions in the environment and visual inspection of pesticide glyphosate of fruits and vegetables.The main contents of this thesis are as follows:1.Based on the Rhodol-HBT structure,a fluorescence sensor Rh-F with AIE+ESIPT mechanism was designed and studied.Due to the synergy between ESIPT and AIE mechanism,it exhibited excellent photophysical properties.For example,solvatochromism,effective aggregated emission near 525 nm,high sensitivity,high selectivity)and large Stokes shift（>180 nm）.By the simple modification of the formation of the spironolactone ring and the introduction of the trifluoromethyl group,which is simultaneously achieved the ON-OFF"specific fluorescence detection for Fe²⁺in the mixed solution of tetrahydrofuran and water（THF:H₂O=7:3,v/v,pH 7.4）.This work motivated us to easily develop fluorescent sensors for different analytes by modifying the phenolic hydroxyl in the Rhodol ring using the AIE+ESIPT mechanism.The development of the AIE+ESIPT fluorophore will provide a viable design strategy for biosensors and imaging.2.Rhodamine 110 dye as the basic structure,the fluorescent probes R-G were designed and synthesized by bis（2-pyridylmethyl）-amine（BPA）modification to realize the"on-off"specific fluorescence detection and the change of the color of the solution from yellow-green to colorless for Cu²⁺based on BPA metal complexation reaction.Due to glyphosate possess a strong metal complexing ability,the signal probe molecule R-G is released by forming a competitive ligand exchange reaction with the BPA group.Result in the fluorescence is recovered,and the color of the solution is restored to yellow-green;The photophysical properties,selectivity and sensitivity of the aqueous solution（MeOH:H₂O=2:8,v/v,pH 7.4）were investigated respectively.The analysis shows that the compound R-G can be specific to recognize Cu²⁺and glyphosate with detection limits as low as 4.67 nM and 0.320 nM,respectively.Finally,it was made into a test strip to realize the detection of the visible color change of Cu²⁺and glyphosate on the fruits and vegetables in daily life R-G（pink）+Cu²⁺（colorless）+glyphosate（pink）.This work realizes the simple and rapid detection of Cu²⁺in aqueous solution and glyphosate in fruits and vegetables with the naked eye by designing and synthesizing the fluorescent probe R-G,which has certain practical application,and also provides strategy to design the fluorescent sensor for detecting pesticides.