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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]

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]