Study On Recognition Of Chiral Carboxylic Acids Based On Small Molecule Fluorescent Probes Containing Tetrahydrothiophene Structure

Chirality is a basic attribute of nature and exists universally in nature.The role of chiral substances in the body of organisms is very important,which is closely related to the biological and chemical reactions in the process of life.Different enantiomers of the same substance have different roles in the body of organisms.The same is true for chiral drugs,where different enantiomers of the same compound have different or sometimes completely opposite properties.In recent years,more and more attention has been paid to the identification of chiral substances.Among these chiral substances,chiral carboxylic acid plays an important role in the development and manufacture of drugs,the synthesis of natural products and asymmetric substances,fine chemical engineering and other aspects of research,and the enantiomer recognition of chiral carboxylic acid is of great significance.Chiral recognition method for fluorescence technology inherent high sensitivity,simple operation method and testing of the advantages of low cost,fluorescent probes are widely used,chiral molecules some stereo specificity of the structure characteristics of fluorescent probe with enantiomers of chiral material selectively,by observing the fluorescence signal to achieve recognition,and easy to synthesis.In this paper,we synthesized a small molecule fluorescent probe（S-S23）containing tetrahydrothiophene structure to recognize the enantiomers of 21 kinds of chiral carboxylic acids.This paper mainly includes the following three aspectsChapter1:three aspects are summarized.The first chapter summarizes the background,significance and main content of this paper.Secondly,the structure recognition mechanism and recognition mechanism of fluorescent probe are reviewed.The third part summarizes the research progress of chiral recognition methods.Chapter 2:In this thesis the structure of the synthesized tetrahydrothiophene 24kinds of small molecular fluorescent probe First use of different substituent of adjacent hydroxy acetophenone and benzaldehyde（or adjacent hydroxy acetophenone with different substituent of benzaldehyde）ethanol solution at room temperature for reaction,synthesis of 24 kinds of adjacent hydroxyl containing different substituent as substrates,chalcone production rate of 37-93%.Then,the synthesized o-hydroxy chalcone was reacted with 2,5-dihydroxy-1,4-dithiane in toluene solution at room temperature,and catalysts C1,C2,and C3 were added to compare the reaction results.The highest yield of probe S（（2R,3S,4S）-4-hydroxy-2-phenyltetrahydrothiophen-3-yl）（2-hydroxyphen-yl）methanone)was 54%by adding catalyst C3.Using nuclear magnetic resonance（NMR）spectroscopy,single crystal diffraction of infrared spectrum technology,and their structures were confirmed,using the same method to C3 as catalyst,and the other contains different substituent of 23 kinds of adjacent hydroxyl as substrates,chalcone preparation tetrahydrothiophene structure of small molecular fluorescent probe,the production rate of 15-80%,through make confirmation on the molecular structure of nuclear magnetic resonance and infrared spectrum.Chapter 3:The third chapter:In this paper,S was used as a fluorescent probe,and the maximum absorption peak of 326 nm was determined as the excitation wavelength of fluorescence by detecting its ultraviolet absorption spectrum.Under this condition,the mixed solutions of S and 21 kinds of chiral carboxylic acid enantiomers（L and D）and S were respectively detected at 1:0.5,1:1,1:2,1:3different molar ratios.By comparing the fluorescence intensity of each carboxylic acid mixture solution with S at the same molar ratio,it was found that blue shift occurred,5（aspartic acid）,6（glutamic acid）,7（glutamine）,8（methionine）,9（tryptophan）,14（3-phenyl lactic acid）,15（mandelic acid）and 16（tartaric acid）enantiomer fluorescence intensity changes significantly,fluorescence intensity ratio（I_L/I_D or I_D/I_L）were 1.18,1.33,1.41,1.21,1.31,1.22,1.24 and 1.26;When the mole ratio of 1:1,3（ser）,4（ala）,5（aspartic acid）,11（proline）,12（complex amino acid）,14（3-phenyl lactic acid）,18（asparagine）and 21（arginine）enantiomer fluorescence intensity changes significantly,fluorescence intensity ratio（I_L/I_D or I_D/I_L）were 1.54,1.94,1.16,1.45,1.19,1.24,1.31 and 1.66;When the mole ratio of 1:2,5（aspartic acid）,6（glutamic acid）,12（complex amino acid）,13（cysteine）,14（3-phenyl lactic acid）,15（mandelic acid）,18（asparagine）,19（l-histidine）and 20（leucine）and 21（arginine）enantiomer fluorescence intensity changes significantly,fluorescence intensity ratio（I_L/I_D or I_D/I_L）were 1.18,1.29,1.19,1.18,1.20,1.13,1.18,1.16,1.18 and 1.49;When the mole ratio of 1:3,3（ser）,4（ala）,5（aspartic acid）,6（glutamic acid）,7（glutamine）,8（h1n1 glycine）,13（cysteine）,16（tartaric acid）,17（malic acid）,18（asparagine）and21（arginine）enantiomer fluorescence intensity changes significantly,fluorescence intensity ratio（I_L/I_D or I_D/I_L）was 1.35,1.15,1.20,1.29,1.17,1.27,1.20,1.22,1.20,1.21 and 1.34.Some chiral carboxylic acids can be identified at different molar ratios.Among them,S to 5（aspartic acid）enantiomers can be recognized at four different molar ratios.When the molar ratio is 1:3,the maximum fluorescence intensity ratio is 1.20.When the molar ratio of S to 4（alanine）enantiomer is 1:1,the recognition effect is the best,and the fluorescence intensity ratio is the maximum 1.94.Based on this finding,when the molar ratio of S₁-S₂₃ is 1:1,the chiral recognition of 4（alanine）enantiomer is performed,and the results show that the recognition effect of S₄ and S₇ is better.The fluorescence intensity ratios（I_D/I_L）were 1.27 and 1.33.