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A novel dual site controlled probe has been developed on the basis of rhodamine and biphenylcarbonitrile unit. The probe showed not only rapid fluorescence response to pH, but also good colorimetric recognition performance for copper ions in the HEPES buffer solution (pH 7.0). The optimal geometric configuration of the probe RhB-H with different structures and the [RhB-H-Cu 2+ ] complex were calculated at B3LYP level by DFT method. On this basis, the response mechanism of pH was analysed combining with the 1 H NMR titration experiment. Moreover, the cytotoxicity studies indicated that the probe had good biocompatibility and low toxicity. Then the probe was also successfully applied on real-time monitoring of the intracellular pH changes by exhibiting different fluorescence and emission intensity. These results demonstrated that the probe could be usefully involved in biological and biomedical research. [ABSTRACT FROM AUTHOR]

A rhodamine-based fluorescent chemdosimeter SHR for Cu 2+ has been developed based on the spirocyclic ring-opening mechanism. SHR is colorless and nonfluorescent due to intramolecular spirocyclization. Upon incubation with Cu 2+ in aqueous media, a highly efficient ring opening of SHR occurs via Cu 2+ -promoted phenylhydrazine oxidation, causing a dual chromogenic and fluorogenic response. The fluorescent intensity at 580 nm increases linearly with Cu 2+ concentration and as low as 10 nM of Cu 2+ can be readily detected. The proposed chemodosimeter shows high selectivity toward Cu 2+ over other metal ions and proves to be able to image Cu 2+ levels in live cells. [ABSTRACT FROM AUTHOR]

Based on fluorescent resonance energy transfer (FRET), we developed a ratiometric fluorescent probe 1 for sensing Cu 2+ . As expected, probe 1 exhibited high selectivity and excellent sensitivity in both absorbance and fluorescence detection of Cu 2+ in aqueous solution. A significant color change from pale yellow to pink could be observed, enabling naked-eye detection of Cu 2+ . Furthermore, fluorescence imaging experiment of Cu 2+ in living MGC-803 cells demonstrated its value of practical applications in biological systems. [ABSTRACT FROM AUTHOR]

Abstract: Three new rhodamine Schiff base sensors 1a–1c have been designed and synthesized as highly sensitive and selective “off-on” chemosensors for Cu2+ detection via the rhodamine ring-opening approach. The sensors display remarkably Cu2+-selective orange fluorescence and pink color switch over a wide range of tested metal ions. Fluorescent imaging of Cu2+ in living cells is also successfully demonstrated. [Copyright &y& Elsevier]