Synthesis And Application Of Pyrazole-pyrazoline-based Fluorescent Probes

Fluorescent molecular probes are widely used in clinical medicine,analytical chemistry,biochemical analysis,and environmental fields.Therefore,the research on the design and synthesis of specialized and specialized fluorescent molecular probes has become a frontier topic that has been widely concerned.The pyrazoline fluorescent probe compounds have the advantages of high fluorescence quantum yield,high yellow fluorescence,high efficiency transmission,rigid planar structure,good luminous performance,etc.Based on the above,this paper designed and synthesized a method for detecting metal ions and Pyrazoline novel fluorescent molecular probes with large conjugated system,the specific contents are as follows:In the first chapter,I searched a lot of literature on pyrazoline compounds,introduced some characteristics of pyrazoline and fluorescent probes and their synthesis methods,and made a composition of fluorescent probes,recognition mechanism and energy calculation method.A brief introduction,on this basis,proposed the design of the paper.Chapter 2:Identification and calculation of iron ions based on pyrazole fluorescent probes based on large conjugated systemsFirst,acetophenone and phenylhydrazine were used as raw materials to synthesize acetophenone phenylhydrazone,and acetophenone phenylhydrazone was synthesized with phosphorus oxychloride and DMF to synthesize1,3-biphenyl-1H-pyrazole-4-aldehyde,synthesizing,3-（1,3-biphenyl-1H-pyrazole-4-mine from 1,3-biphenyl-1H-pyrazole-4-aldehyde and acetophenone via aldol condensation reaction）-1-phenyl-acetone,and then hydrazine hydrate under glacial acetic acid reflux conditions through ring closure reaction to obtain the corresponding pyrazoline compound,its structure can be confirmed by ¹H NMR,¹³C NMR and HRMS.Through ultraviolet absorption spectrum and fluorescence spectrum,it can be concluded that probe L has high selectivity and sensitivity in HEPES buffer solution[v（THF）:V（Water）=1:1,0.02m M,p H=7.4].And anti-interference.According to Benesi-Hildebrand calculation and Job’s plot curve,it can be seen that probe L and iron ion are 1:1 coordinated.Through infrared spectroscopy test,it is found that the-OH,C=N,C=O groups of probe M can be matched with Fe³⁺The density of the electron cloud is reduced,and the probe L and Fe³⁺are combined in a 1:1 form.Fe³⁺inhibits the C=N-N isomerization of the probe L,thereby generating quenching of the fluorescence of the probe L itself.Effect,the detection limit of pyrazoline fluorescent probe L and iron ion is 4.9x10^-8M.Complexation constant Ka=5.75x10³M^-1.Chapter 3:Synthesis and Application of Pyrazoline Fluorescent Probes Based on Chalcone StructureUsing o-hydroxyacetophenone and phenylhydrazine as raw materials,synthe size o-hydroxyacetophenone phenylhydrazone,then react o-hydroxyacetophenone phenylhydrazone with phosphorus oxychloride and DMF to synthesize 1-（2-hydr oxy-phenyl）-3-phenyl-1H-pyrazole-4-aldehyde,obtained by condensation of 1-（2-hydroxy-phenyl）-3-phenyl-1H-pyrazole-4-aldehyde with acetophenone by aldol c ondensation Unsaturated ketone,and then ring closure with hydrazine hydrate u nder glacial acetic acid reflux conditions to obtain the corresponding pyrazoline compound,its structure can be determined by ¹H NMR,¹³C NMR and HRMS,calculated by Gaussian in the absence of added ions and added ions The energ ydifference is found that the addition of ions can make its structure more and more stable.The experiment of adding PPi proves that the process of the fluor escent probe M recognizing Fe³⁺is reversible,and the fluorescent color of thea dded iron ion can be seen to change from colorless to colorless under the ultr aviolet lamp.Bright yellow can achieve the effect of naked eye recognition.T he complex ratio of the fluorescent probe M to Fe³⁺is 1:1,the complex const ant K_a=2.6x10⁵M^-1,and the detection limit is 3.9x10^-10M.Chapter 4:Synthesis of pyrazoline fluorescent probes and their application in aqueous solutionsFirst,o-hydroxyacetophenone and phenylhydrazone were used as raw mater ials to synthesize o-hydroxyacetophenone phenylhydrazone,and then reacted wit h phosphoruso xychloride and DMF to synthesize 1-（2-hydroxy-phenyl）-3-phenyl-1H-pyrazole-4-aldehyde,followed by condensation reaction with o-hydroxyacet ophenone aldol to produce ketones,and then pyrazoline compounds are prepare d by cyclization with hydrazine hydrate under acetic acid reflux condition and heating to 120°C.The structure is composed of ¹H NMR and ¹³C NMR And HRMS can be determined,through ultraviolet absorption spectrum and fluoresc ence spectrum,it is found that the addition of other metal ions does not chang e,only the addition of iron ions will change,through Gaussian optimization of structure,calculation of its orbital energy level difference,it is found that the addition of iron ions makes the structure become more The more stable,by ad ding different iron ion concentrations,a linear regression equation is made,wit h 1/F-F₀as the ordinate and(Fe³⁺)^-1M^-1as the abscissa.The equation y=0.00415x+1.53x10^-4,R²=0.989,K_a=3.69x10⁶M^-1,the detection limit is 1.58x10^-10M,ind ic ating that the probe has high selectivity,sensitivity,and low detection limit anti-interference.The complex ratio of probe N and Fe³⁺is 1:1.The process of recognizing Fe³⁺by fluorescent probe N is proved to be reversible by adding PPi.Chapter 5:Synthesis and application of fluorescent probes based on pyrazoloneO-hydroxyacetophenone and phenylhydrazine form o-hydroxyacetophenone phenylhydrazone under the action of absolute ethanol.Phosphorus oxychloride and DMF are mixed and stirred,then o-hydroxyacetophenone phenylhydrazone is added to the mixture of DMF to form unsaturated Aldehyde is then condensed with acetophenone via aldol to form unsaturated ketone.The unsaturated ketone is completely dissolved with glacial acetic acid,transferred to an oil bath and added with80%hydrazine hydrate drop by drop to form a pyrazoline compound.The structure is derived from HRMS,¹H NMR and ¹³C NMR were jointly determined that the Gaussian optimization structure and operation obtained the orbital energy level difference.This result was consistent with the fluorescence spectrum.It was found by infrared testing that certain groups of the pyrazoline compound coordinated with Fe³⁺to reduce the density of the electron cloud The binding ratio of probe O to Fe³⁺is 1:1,and adding anions that recognize ions has no effect on the results.Use 1/F-F₀as the ordinate and(Fe³⁺)^-1M^-1as the abscissa to make a linear regression graph,and get the linear regression equation y=8.6x10^-5x+0.00181,R²=0.9917,K_a=2.1x10⁶M^-1,and the detection limit is 3.9x10^-11M.