| The advantages of molecular fluorescent probes for sensing can be summarized as followings: high sensitivity of detection, observation in situ, good selectivity, low cost, easy operation and so on, and they have been widely used for cation, anion, amino acid, nucleic acid and protein detection. The phenoxazinium and benzo[a]phenoxazinium dyes were reported as bio-activites drugs and have excellent photophysics and photochemistry properties, such as high molar extinction coefficient, long wavelength excitation and emission, water solubility, low toxicity, good membrane permeability. Therefore, phenoxazinium and benzo[a]phenoxazinium dyes are suitable structures for molecular fluorescent probe.In this dissertation, there fluorescence molecular probes (probe 5, 9, 14), owning phenoxazinium or benzo[a]phenoxazinium skeleton, were synthesized. They are long-wave emission and fully water-soluble fluorescent sensors with good membrane permeability for the selective detection of mercury(Ⅱ) ion, copper(Ⅱ) ion and zinc(Ⅱ) ion respectively.Probe 5 (3-(10-Aza-1,4-dioxa-7,13-dithiacyclopentadec-10-yl)-7-(diethylamino)ph -enolxazin-5-ium chloride) is a phenoxazinium-based chemosensor bearing an anilino thiaazacrown for detection of mercury(Ⅱ) ion. The best excitation wavelength is 590 nm, and the maximum emission wavelength is in the near infrared region (695 nm). It is a selective ratiometric (UV-vis spectrum) and tun-off (fluorescence) probes for detection of Hg2+ in pure water without any organic co-solvent. The detection limit is 50×10-6 M in water.Probe 9 (3-(Diethylamino)-7-di(2-picolyl)amino)phenolxazin-5-ium chloride) is a phenoxazinium-based chemosensor bearing an di(2-picolyl) amine unit for detection of copper(Ⅱ) ion. The best excitation wavelength is 560 nm, and the maximum emission wavelength is in the near infrared region (673 nm). It is a selective tun-off fluorescence probes for detection of copper(Ⅱ) ion in pure water without any organic co-solvent, and the corresponding quenching mechanism was elucidated by ab initio calculations. The detection limit is 5×10-6 M in water. The application of 9 to cultured cells was checked and the results suggested that 9 has good membrane permeability and can be used to monitor changes in intracellular copper(Ⅱ) ion.Probe 14 (5-((2-(bis(2-picolyl)amino)ethyl)amino)-9-(ethylamino)-10- methylbenzo [a] phenoxazin-7-ium chloride) is a benzo[a]phenoxazinium-based chemosensor bearing N,N-di-(2-picolyl)-ethylenediamine unit for detection of zinc(Ⅱ) ion. The best excitation wavelength is 579 nm, the maximum emission wavelength is in the near infrared region (653 nm). It is a selective fluorescence enhance probes for detection of zinc(Ⅱ) ion in PBS buffer at pH 7.4 without any organic co-solvent. Probe 10 can work without interference in pH ranged between 6.5 and 7.7 with a detection limit of 1.5×10-6 M in PBS buffer at pH 7.4. The application of 10 to cultured cells was checked and the results suggested that 10 has good membrane permeability and can be used to monitor changes in intracellular zinc(Ⅱ) ion. At the same time, the MTT test indicated the probe 10 have no obvious cytotoxicity in the concentration between 10×10-6 M and 30×10-6 M. |
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