Study On Fluorescence Enhancement Hypochlorite And Cyanide Probes

This thesis is mainly devoted to the fluorescence probes for cyanide and hypochlorite ions.The physiological role of cyanide and hypochlorite ions in human cells and the significance of detecting these two ions are firstly analyzed.It also briefly explains the advantages of "turn-on" recognition and outlines the different sensing mechanisms in recent years and the current status of detection for cyanide and hypochlorite ions.Three kinds of fluorescent probes with good recognition properties and biocompatibility were designed and synthesized.Their photophysical properties and recognition properties were studied.The recognition mechanism and biological imaging in living cells were explored.(1)Pyridine salt derivatives 1-4(2)Schiff’s base derivatives 5-8(3)Fluorescein derivatives 9 and 10In the pyridine salt derivatives,the obtained compound 1 was characterized by 1H NMR,13C NMR and high resolution mass spectrometry.After titration experiments and selective experiments,it was found that compound 1 has a specific recognition effect on cyanide ion,and cyanide ions can be identified in a colorimetric ratio way under the solvent environment of VTHF/VPBS=4/1.In addition,compound 1 can recognize endogenous cyanide in cassava cells and PC12 cells.Compounds 3 and 4 can recognize cyanide anions in pure organic solvents,but the probes have better recognition properties for bisulfite.Then the recognition properties of compounds 3 and 4 for bisulfite were investigated,and the reason why compound 4 was more sensitive than compound 3 was studied.The mechanism of compound 3 for bisulfite is Mechanel addition mechanism,which is reasonably deduced by mass spectrometry.A total of four molecules of compounds 5-8 were obtained in the Schiff base derivatives system,and the detection properties of the probes for hypochlorite ions were investigated.The theoretical calculation indicates that the dihedral angle between the pyrene group part and the terminal pyridine ring in compound 5 is 54.92°.The main plane of the molecule is severely distorted,which limits the transfer of charge within the molecule,so the fluorescence intensity is very poor.After response to hypochlorite ions,the pyrenecarboxylic acid is generated with the blue fluorescence enhancement.In addition,compound 5 can recognize exogenous hypochlorite ions in A549 cells by bioimaging experiments.Compound 6 can response to hypochlorite ions in the form of colorimetric ratio,and the recognizing property of compound 7 is similar to that of compound 5 because of their similar structures.Compound 8 has the excited state intramolecular proton transfer(ESIPT)property and photo-induced electron transfer(PET)effects.In the PBS/DMSO resolution,as the increasing addition of PBS component,the phenol imine tautomer is transformed into a ketoamine tautomer,and the fluorescence intensity of the two interconversion forms is very weak due to the PET effect.Compound 8 can also recognize hypochlorite ions by absorption titration spectroscopy.In addition,compound 8 can recognize aluminum ions in the form of fluorescence enhancement.The mass spectrometry data after the addition of aluminum ions indicate that two molecules of probe coordinate with one aluminum ion to form a stable complex.Two fluorescent probe molecules compounds 9 and 10 were obtained.Through the fluorescence titration of the recognition of hypochlorite by compounds 9 and 10,it can be found that the recognition methods of compounds 9 and 10 are completely different.Compound 9 can recognize hupochlorite in the form of fluorescence quenching,but the recogniton properties of compound 10 is opposited to compound 9,so the in-depth study of the recognition mechanism of the two compounds is carried.The identification mechanism of the compounds reveals that the presence of the hydroxyl group is crucial.The hypochlorite ion partially oxidizes the hydrazide of compound 10 to form the diimide intermediate,and a hydrolysis process further undergoes a hydrolysis process,producing a strong green fluorescent fluorescein and 8-hydroxyjulonidine-9-formaldehyde.On the other hand,compound 9 can not be ring-opened by the induction of hypochlorite ions.Since compound 9 does not have a"proton storage unit",protons cannot be transferred freely,compound 9 will not become the form of a diimide intermediate.Therefore,the next hydrolysis process cannot be carried out.After that,a bioimaging experiment was conducted on the compounds.The experiment showed that compound 9 could be targeted to lysosomes and could recognize exogenous hypochlorite ions and compound 10 could be recognized by PMA and LPS in RAW 246.7 cells.Besides,compound 10 can also track the endogenous hypochlorite ions generated in zebrafish due to tissue damage.Furthermore,as the excellent properties of compound 10,an imaging experiment in vivo on mice model was carried out,and the experiment show that the fluorescent signal of 10 in the subcutaneous tissue of the mouse can be successfully detected.