Synthesis And Properties Of Fluorescent Probes Based On Coumarin And Flavonoid Skeleton

Many biological molecules and organelles in cells have extremely important physiological functions,which are very important for their identification and detection.Fluorescent probe detection has the advantages of high sensitivity and good specificity.It is currently widely used in the identification and detection of substances in living systems.Coumarin compounds are a class of natural products with an aromatic odor.Their mother core structure is benzo-?-pyrone,which introduces electron-withdrawing groups and emits strong fluorescence.Flavonoids are widely present in some plants in nature,and the structure is based on benzo-y-pyrone.Many of these derivatives have intramolecular proton transfer effects,which leads to their special fluorescence properties.In this thesis,two types of fluorescent probes were designed and synthesized based on coumarin and flavonoids,which were applied to the detection of intracellular biological sulfhydryl groups and intracellular targeted mitochondria imaging.Coumarin fluorescent probes for detecting intracellular biological sulfhydryl groups:This chapter uses coumarin as the mother nucleus,and designs and synthesizes three kinds of fluorescent probes to detect biological thiols,cysteine(Cys),and isotype hemi Cystine(Hcy)and glutathione(GSH).Probe A uses "dimethylpyranilonitrile" as a derivative.The reason is that the introduction of dimethylpyranmalononitrile at the 3-position of coumarin extended the conjugate system,and the wavelength was red-shifted to 648 nm,which has a good intramolecular charge transfer effect.The probe is compatible with GSH and Cys.Presents a quenching fluorescence response mode.Probe B is a "thiophenol-aldehyde group" as a derivative.Since the thiophenol group is introduced at the coumarin position 4,its water solubility is good,and the reaction of Probe B with GSH and Cys is 470 nm and 540 nm shows strong fluorescence enhancement,which is an enhanced fluorescence response mode.Probe C is a "thiophenol-malononitrile group" derivative.It is based on the derivatization of the aldehyde group at position 3 to a malononitrile group.The change in the reaction site of probe C causes In addition to GSH and Cys responses,it has specific responses to sulfhydryl ion.Flavonoid probes for intracellular mitochondrial targeting:This chapter uses 3-hydroxyflavonoids as the fluorescent mother nucleus and triphenylphosphine as the targeting group to synthesize an example of fluorescence for mitochondrial specific imaging of living cells Probe D.Probe D is a derivative of the "3-hydroxyflavonone-triphenylphosphine" group.The excited intramolecular proton transfer(ESIPT)mechanism of the 3-hydroxyflavonoid moiety gives it excellent fluorescence properties.Fluorescence can change with changes in pH.The triphenylphosphine moiety is lipophilic and can be specifically embedded in the inner membrane of the mitochondria and stably bind to the mitochondrial marker in the cell.Fluorescence spectrum testing and cell fluorescence imaging experiments have shown that the probe is suitable for targeted labeling and fluorescence imaging of mitochondria in cells.