Study On Multiple Recognition Site Fluorescent Probe To Selective Recognize For Biological Thiols

This thesis mainly expounded the physiological function in human cells of three kinds of biological thiols including cysteine?Cys?,homocysteine?Hcy?and glutathione?GSH?and the significance of detecting of these biological thiols.This thesis also summarizes the research progress of chemosensors for biological thiols in recent years.Four categories materials with good fluorescence properties and biocompatibility were designed and synthesized.Photophysical properties and corresponding identification properties of four categories compounds were investigated.The recognition mechanism and biological imaging of the compounds in living cells were also studied.?1?Schiff base compounds 1,2 and 1-Cu²⁺?2?Benzothiazole/pyridine iodide compounds 3-5?3?Spiropyran compounds 6-8?4?Chalcone compounds 9 and 10Two Schiff base compounds 1,2 and copper ions complexes 1-Cu²⁺were synthesized,characterized by nuclear magnetic resonance?NMR?H spectra,C spectra and high resolution mass spectra.Titration experiment indicates that compound 1 has specific recognition effect to GSH in pure PBS buffer solution.Compound 2 without hydroxyl group can not response to the biological thiols,which also verify that the hydroxyl is necessary for the recognition for biological thiols.Compound 1 can also cooperate with copper ions in acetonitrile and then lead to fluorescence quenching and the formation of a new absorption peak.Complex 1-Cu²⁺can recognize Cys by the displacement mechanism,and result in absorption peak and fluorescence recovery.Probe 1 and 1-Cu²⁺have been used to identify biological thiols in living cells.Compound 1 possesses multiple identification sites including hydroxyl group,oxygen and nitrogen atoms cooperating with copper ions,then this compound can selectively recognize these three biological thiols.Three benzothiazole/pyridine iodized salt compounds 3-5 were synthesized in the ienzothiazole/pyridine iodized salt compounds system.The photophysical properties and identification properties for biological thiols of these compounds were investigated.Both of GSH and Hcy can give rise to the absorption and fluorescence change of compound 3 and this compound can distinguish them from Cys.After the addition of Cys,to compounds 4 and 5,fluorescence intensity decreases and fluorescence peak is red-shifted.Selectivity experiment indicates that compound 5 has good selectivity,which can specifically recognize GSH by absorption spectra and can identify Cys and GSH by fluorescence spectra.And then three biological thiols can be selectively recognized by compound 5 using absorption and fluorescence spectra.Three compounds have long fluorescence band,and color and fluorescence change before and after biological thiols added is obvious.Compounds 3-5 are a kind of fluorescence enhanced biological thiols probes.The response mechanism is Michael reaction between carbon-carbon double bond and biological thiols,which induces the decrease of molecular conjugation and then lead to fluorescence decrease.In the pyrene-spiropyran system,three compounds 6-8 were synthesized and the photophysical properties of the compounds were investigated.The results indicate that both GSH and Hcy can give rise to similar absorption change of compound 6,but it is more sensitive to GSH by fluorescence spectrum.Compound 7 has good absorption and fluorescence response to GSH,while compound 8 is more sensitive to Hcy.Three compounds have good selectivity.Cyanide ion can rise similar response characteristics to biological thiols,thus we concluded that the recognition mechanism of them is same.Michael addition reaction takes place in the double bond.This kind of compounds have high sensitivity and obvious fluorescence enhancement effect.In the derivative chalcone system,two compounds 9 and 10 were synthesized.The photophysical properties and aggregation-induced emission?AIE?properties of compound 9 were analyzed.Identification properties of compounds 9 and 10 to biological thiols in PBS buffer solution were investigated.Compounds 9 has good absorption and fluorescence response to GSH and ultra low detection limit.Compound 10 also has response to GSH,but the recognition effect is weaker than that of compound 9.Compound 9 has specificity for the identification of GSH,and can be used between pH 6-10.The recognition mechanism is also Michael addition between GSH and carbon-carbon double bond in conjugated bridge.And compound 9 was also successfully used to biological imaging in living cells.