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The introduction of into a bis-rhodamine spirolactam system afforded a new fluorescent sensor for Cu2+ ions, SRR, which contained a new tridentate sulfur ligand. SRR showed excellent specificity for Cu2+ ions over other cations (including Cu+, Hg2+, and Fe3+), very high sensitivity (10 n M), and a rapid response time (3 min). The detection mechanism was investigated by 1H NMR, 13C NMR, 31P NMR, and ESR spectroscopy, MS, and Gaussian calculations. Coordination of a Cu2+ ion to the tridentate sulfur ligand, which promotes ring-opening of the rhodamine groups, followed by a spontaneous (Cu2+ into Cu+), has been proposed as the sensing mechanism. [ABSTRACT FROM AUTHOR]

Fluorescence resonance energy transfer (FRET) has beenwidely usedas a spectroscopic technique in various areas such as structural elucidationof biological molecules and their interactions, in vitro assays, invivo monitoring in cellular research, nucleic acid analysis, signaltransduction, light harvesting, and metallic nanomaterials. Meanwhile,based on the mechanism of FRET, a series of FRET nanomaterials systemshave been recently developed as novel chemical sensors and biosensors.Compared with those based on small molecules traditional FRET systems,the surface chemistry of nanomaterial has encouraged the developmentof multiple probes based on linked recognition molecules such as peptides,nucleic acids, or small-molecule ligands. This critical review highlightsthe design and the applications of sensitive and selective ratiometricnanoprobes based on FRET. We focus on the benefits and limitationsof nano-FRET systems and their applications as chemical sensors andbiosensors. [ABSTRACT FROM AUTHOR]

The introduction of Lawesson's reagent into a bis-rhodamine spirolactam system afforded a new fluorescent sensor for Cu(2+) ions, SRR, which contained a new tridentate sulfur ligand. SRR showed excellent specificity for Cu(2+) ions over other cations (including Cu(+), Hg(2+), and Fe(3+)), very high sensitivity (10 nM), and a rapid response time (3 min). The detection mechanism was investigated by (1)H NMR, (13)C NMR, (31)P NMR, and ESR spectroscopy, MS, and Gaussian calculations. Coordination of a Cu(2+) ion to the tridentate sulfur ligand, which promotes ring-opening of the rhodamine groups, followed by a spontaneous reduction reaction (Cu(2+) into Cu(+)), has been proposed as the sensing mechanism., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Born to dye: Five fluorescein analogues were synthesised (see scheme). One analogue was found to emit in the NIR region with a high quantum yield, excellent photostability and good permeability. Three derivatives were found to specifically stain mitochondria and one dye responds to thiols with a strong turn-on NIR fluorescence signal and colorimetric change, in vitro and in vivo., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)