Synthesis And Properties Of New Long-wavelength Fluorescent Probes

Long-wavelength (near infrared or similar to near infrared) fluorescent probes, not only have stronger organization permeability and smaller fluorescent interference, but also have less light damage to biological tissue, thus, they are widely used in vivo imaging. In recent years, more and more chemists are being attracted to exploiting long-wavelength fluorescent probes.In this dissertation,2-(7-(diethylamino coumarin)-7-diethylamino-l-benzopyrylium-4-)3,5-bis(trifluoromethyl) benzenethiol (1), N,N-diethylrhodol-Benzothiazole salt (3) and2-(7-diethylamino-4-boronobenzylidene-1,2,3,4-tetrahydroanthracen-xanthen-10-) benzoic acid (4) were designed and synthesized based on the index compound2-(7-(diethylamino coumarin)-7-diethylamino-l-benzopyrylium-4-) benzoic acid (CB), N,N-diethylrhodol (DER) and2-(7-diethylamino-1,2,3,4-tetrahydroanthracen-xanthen-10-) benzoic acid (G), respective-ly. Among these probes, probe1was used to detect cysteine/homocysteine (Cys/Hcy), probe3was used to detect sulfite (SO32-) and probe4was used to detect D-Fructose. Meanwhile, the performances of these probes were analyzed systematically. Then, probe1and3were applied in the fluorescent imaging analysis of human liver cancer cells (HepG2).The main contents are as following:1. NCL (Native chemical ligation) was introduced into dye molecules of Spirocyclization of xanthene which have infrared emission performance, and probe1which was used to detect Cys/Hcy selectively in human body, was constructed successfully. When NCL occurred between probe1and Cys/Hcy at room temperature, amide compound was generated. Then spirocyclization reaction occured in molecules of this amide compound, thus, the large π-conjugation system in the molecules was broken. In this process, blue shifts were observed on both absorption and fluorescence spectra. Fluorescent ratiometric detection of Cys/Hcy was realized base on the above. What’s more, probe1was successfully used in the fluorescent imaging analysis of HepG2.2. Nucleophilic Addition reaction was introduced into dye molecules of DER-benzothiazole class, and probe3was successfully constructed to selectively detect SO32-in human body. At room temperature, adduct3-SO32-was generated from nucleophilic addition reaction between probe3and SO32-, thus, the large-conjugation system in the molecules was broken. In this process, blue shifts were observed on both absorption and fluorescence spectra. Under the same condition, reaction system was not affected by other anions and sulfhydryl compounds, such as glutathione (GSH) and Cys. Therefore, fluorescent ratiometric detection of SO32-could be accomplished through above procedures. Further, probe3was applied in the fluorescent imaging analysis of HepG2successfully.3. probe4was synthesized from the aldol condensation reaction of compound G and2-formylphenylboronic acid. This probe consists of boron (electron withdrawing) and xanthene (electron donating), and has ICT process which results in weak fluorescence. After accession of D-Fructose, the six-member cyclic ester was created from reaction of boron hydroxyl in probe4and cis dihydroxy in D-Fructose, which interrupted ICT process and resulted in strong fluorescence. It was rather different from other saccharides, such glucose, mannose and galactose.