Development Of Molecular Fluorescent Probes Based On Naphthalimide And Phenothiazine In ROS And Microenvironment Detection

Organic small molecular fluorescent probe(OSMFP) is a series of sensing materials, which used the fluorescence as signal. Most of OSMFPs show of excellent properties, such as brightness, easy modification, tunable wavelength in UV-Vis-NIR region and good quantum efficiency. Compared to the nanomaterials, OSMFPs always showed low toxicity and fast metabolism in organism. As a result, the OSMFPs act as the important roles in many fields, such as environmental monitoring and in vivo diagnosis.In this thesis, we describe rational design of series of phenothiazine and naphthalimide derivatives as new fluorescent chemosensors with different emission colours. Furthermore, this work discussed the strategy to enhance the aggregated emission by introducing the conjugated segments through single bond. The main contents and results are summarized in the following aspects:In chapter 1, the development and major sensing mechanisms of fluorescent probes are reviewed. Then, the research strategies of this dissertation are proposed.In chapter 2, the research progress of phenothiazine-related aggregate luminescent materials was summarized. Then, a phenothiazine-based OSMFP(QC1) was designed with the center sulfur atom as the recognized unit for HClO. The structure of QC1 was characterized by 1H NMR, 13 C NMR and HRMS. The photophysical properties and aggregated-induced emission properties were studied by absorption and emission spectra. The sensing properties of QC1 in HEPES showed rapid responsibility, high sensitivity and good selectivity for HClO. Finally, the sensing mechanism was determined by NMR and MS titration experiments.In chapter 3, we designed and synthesized a double naphthalimide coupling fluorescent rotor(BNAP). As a typical intramolecular changer transfer(ICT) unit, naphthalimide can output obvious ICT emission by attaching a donor at 4-site of the dye. In this work, we evident that the rotor with two naphthalimide segments linked through a single bond can also process the ICT emission. BNAP showed strong polarity-related spectral variation in common organic solvents and enhanced emission at long wavelength in high viscosity medium. Furthermore, BNAP showed special emission in water different from many naphthalimide derivatives. Some experiments were performed to verify the aggregated induced emission. Finally, a viscometer and viscosity-related thermometer was constructed in this work.In chapter 4, three different naphthalimide aggregation induced luminescence materials NAPB, NAPFB, NAP-TBA were designed and synthesized with different push-pull electronic ability. The three compounds and intermediates were characterized by NMR and MS. We studied the photophysical properties of the dye in solid state and different solution by absorption and steady-state fluorescence spectra. The sensing properties of these compounds in viscosity, pH and other microenvironmental parameters were discussed.In chapter 5, through the same single bond coupling design strategy, used triphenylamine with the giving electronic property as nucleus, by the Suzuki coupling reaction, designed and synthesized bipyridine triphenylamine fluorescent dye with D-?-A structure. Furthermore, strong electron-withdrawing nitro ethylene unit was introduced through the Knoevenagel condensation to synthesize a class of fluorescence probe(DPTPA2) in response to sulfite. The study of the photophysical properties of DPTPA2 indicated that an obvious red fluorescence over 600 nm occurred in aqueous solution and the powder state. The red fluorescence represented that the emission of DPTPA2 red shift a lot than it in common organic solvents, which implied the aggregation luminescence. Based on Synchronous fluorescence spectroscopy, DPTPA2 spectra exhibited high selectivity to sulfite anions in ratiometric mode. Upon addition of the sulfite, the synchronous signal was hypochromatic shifted from 474 nm to 362 nm, indicating the decreasing conjugate system of the probe. We believed that came from the nucleophilic attaching of sulfite to the olefinic bond. To verify this hypothesis, we used dimethylamino analogue of DPTPA2 to react with sodium sulfite and tried to monitor its titration products by NMR and MS tools. Compared with conventional fluorescence method, synchronous fluorescence method has a distinctly separated dual emission bonds, which showed more suitable for constructing the ratio fluorescent probe system.In chapter 6, due to the important role of cysteine in biorganism, we designed and studied the cysteine fluorescent probe(PHS) based on phenazine. the phenazine, an analogue of phenothiazine, was selected as fluorophore, which could avoid the interference from the sulfur atom in phenothiazine to cystine thiol. With similar design of the previous chapter, the cyanoacrylate unit was introduced to phenazine as the recognized site. The strong electron-withdrawing effect of cyano group and carboxyl group can enhance the electropositive of ? carbon atom, which was conducive to the nucleophilic attack efficiency of sulfhydryl compounds. By activating the carboxyl group by NHS-ester, PHS showed increasing ability to capture the amino group. The absorption, emission and excitation spectra were used to explore the specific response of PHS to cysteine in buffer. Furthermore, we verified the sensing mechanism of PHS to cysteine by the NMR and MS titration experiments. Finally, we further applied PHS to imaging the distribution of thiols in Hela cells. The NEM was used to verify the imaging signal from the reaction product of PHS and cysteine, which showed scavenging ability towards the intracellular biothiols.In chapter 7, a series of fluorescent probe molecules based on BODIPY fluorophore were designed, which showed tunable spectral properties from the visible to near infrared region. Firstly, two red compounds BNB-1 and BNB-2 were synthesized with indole precursor instead of one of pyrroles. The relationship between structure, spectral properties and solvent polarity of the compounds were discussed by absorption, fluorescence spectroscopy, fluorescence lifetime spectroscopy and cyclic voltammetry, respectively. Secondly, a near-infrared emission compounds BODIPY-PhOSi was synthesized by introducing p-dimethylaminobenzaldehyde, which can be used as the fluorescent probe for fluoride ions.In chapter 8, summary.