A water-soluble fluorescent pH probe based on perylene dyes and its application to cell imaging.

A fluorescent pH probe, N,N'-bi( l-phenylalanine amine)-perylene-3,4;9,10-dicarboxylic diimide (PDCDA) was synthesized and used for pH sensing in living cells. A significant fluorescence intensity change was observed over a pH range from 7.0 to 4.0. Electrostatic potential maps (MEP) suggested that the electronic repulsion between PDCDAs was increased by the high negative electrostatic potential which resulted in a high water solubility of PDCDA. PDCDA was successfully applied as a high-performance fluorochrome for living HeLa cell imaging. The results demonstrate that the probe PDCDA is a good candidate for monitoring pH fluctuations in living cells with good water solubility, low cytotoxicity, high fluorescence quantum yield and photostability.

Real roles of perylene diimides for improving photocatalytic activity.

Three novel visible-light-driven composite photocatalysts: five-membered O-heterocyclic annulated perylene diimide doped TiO2 (PDI-1/TiO2), 1-phenol-N,N'-dicyclohexyl perylene-3,4,9,10-tetracarboxylic diimide doped TiO2 (PDI-2/TiO2), and N,N'-dicyclohexyl perylene diimide doped TiO2 (PDI-3/TiO2), were synthesized using a hydrothermal synthesis method. The effects of introducing PDIs with different structures into TiO2 were evaluated by assaying the photodegradation rate of Methylene Blue (MB). The photoactivities of the PDI-1/TiO2 and PDI-2/TiO2 catalysts were better than that of PDI-3/TiO2. This is because the large surface area of PDI-1 nanorods and PDI-2 nanobelts extended the 1D charge carrier channel, which facilitated electron transfer to the TiO2 surface and improved the photocatalytic activity of the composites. The PDI-1/TiO2 composite showed the highest photoactivity, and the activity remained at 86.4% after four reuse cycles. The extended π-π stacking of self-assembled PDI-1 and the strong interactions between self-assembled PDI-1 and TiO2 played significant roles in accelerating charge transfer and decreasing recombination of photogenerated electron-hole pairs. The steric hindrance of the phenoxy substituent at the bay position of PDI-2 prevented the PDI-2 nucleus from contacting TiO2 and weakened the interaction between PDI-2 and TiO2, which further resulted in the low photoactivity of PDI-2/TiO2. This work provides a practical way to improve the performances of traditional organic and inorganic composite photocatalysts.

Rapid and sensitive spectrofluorimetric determination of trace amount of Cr(III) with o-vanillin-8-aminoquinoline.

A novel fluorescent reagent o-vanillin-8-aminoquinoline(OVAQ) was synthesized, and its infrared spectrum, elemental analysis and acid-base dissociation constants were obtained. The fluorescent reaction of this reagent with Cr(III) was studied. In acetonitrile-water (1:1, (v/v)) medium of pH 6.00, Cr(III) could react with fluorescent reagent OVAQ (lambda(ex/em)=280/314nm) to form a 1:1 non-fluorescent complex. The linear range of the spectrofluorimetric method proposed was from 8.2 to 130mugl(-1), and the detection limit was 2.5mugl(-1). The interferences of 25 foreign ions were also studied. This method could be easily performed and was successfully applied to the determination of Cr(III) and total chromium in domestic and industrial waste water samples.