Synthesis Of Coumarin Ratiometric Fluorescent Probes Of OCl~-/CN~-/Cys And Investigation Of Spectral Properties

Ratiometric fluorescent probes have developed rapidly since the80’s because of manyadvantages they have, and the method of measuring technology it adopts overcomes somedefects the previous single-wavelength probes have, such as the data they acquired is thefluorescence intensity of a single wavelength that is influenced easily by external environment(eg. temperature), the sample concentration, the instrument conditions (eg. light scattering,light bleaching, background light) and so on. So we must control strictly the experimentalcondition to get more accurate results. Therefore in my thesis, we design mainly theratiometric fluorescent probes and have a preliminary test in the right environment.Firstly, the paper introducs several mechanism for designing the ratiometric fluorescentprobes, Fluorescence Resonance Energy Transfer (FRET), Intra-molecular Charge Transfer(ICT), Photoinduced Electron Transfer (PET), formation or disappear of Monomer andExcimer, Excited States Intramolecular Proton Transfer (ESIPT) and so on. The probes in mypaper work were designed depending on the ICT mechanism and using coumarin compoundsas chromophores.The first ratiometric fluorescent probe we design is compound1b which detect OCl~-. Theprobes reported before are mainly single-wavelength probes, and our laboratory haddeveloped a ratiometric probe several years ago, but it just works in the pH9.0, notappropriate for application under physiological environment. Now, the compound1b couldplay a role in pH6.0~9.0and its selectivity and competivity effects are very good. Throughseparating the reaction product and characterizing it, we got its structure and knew the probeis reduced to aldehyde. And the effect of ratio imaging in cell is also evident, achieving ouraims. The second probe in my paper has a simple structure, easy acquiration but the effect fordetecting CN~-is very good. Compared to the previous probes, the adrantages are the lowdetection limit, wide dynamic range, rapid response, and the testing process is hardlyinterferenced by other anions; Through the DFT calculation, we got the optimal structure andthe most likely reaction site; then the real-time monitoring by MS,~1HNMR to the testingprocess, we preliminarily discussed the response mechanism and prepared the product toverify our hypothesis. The third probe Ratio-Cys is the first probe which can take a differencecysteine from homocysteine, glutathione. The test mainly sudies the titration, selectivity,competivity and dynamical process. From the secondary dynamics constant, we know thespeed that Ratio-Cys reacting with cysteine is much faster than that of homocysteine andglutathione which even can’t be able to react completely. This may be the root cause of high selectivity. Mass spectrometry monitoring for the reaction process proved that the reactioncomply with the Baldwin rules to get a seven-endo-ring, firstly, then have a addition reaction.According to the Baldwin rule,we also know why the probe can’t react with Hcy, GSHrapidly, completely. The fluorescence emission wavelength of before and after reaction have anotable blue shift and the cells ratio imaging effect is satisfied.