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A fluorescent chemodosimeter ( TPAII-2 ) for Hg 2+ was designed with four sulphur atoms in its trigger based on a multisulphite strategy and a control sensor ( TPAII-1 ) was synthesized according to the common design with the deprotection of dithiol. Compared to TPAII-1 , TPAII-2 displayed optimizing selectivity towards Hg 2+ over Ag + , one of the most interference species with strong sulphophile affinity. Further studies indicated the TPAII-2 still maintained the fast detection rate (<2 min) and high sensitivity (detection limited = 15 nM) in HEPES (contain 1% DMSO as cosolvent). As far as we known, sensors based on the deprotection of dithiol were still seldom reported in such solution because of their poor sensing actions in bulk of the aqueous. At last, TPAII-2 was utilized to monitor the Hg 2+ in Hela cells, which evidenced TPAII-2 could maintain the excellent sensing properties in more complex circumstance. More importantly, this recognizing method provided a powerful platform for sensing Hg 2+ in complex systems and highlighted the designing strategy combing the advantages from both coordination-based and reaction-based fluorescent sensors. [ABSTRACT FROM AUTHOR]

Based on fluorescein, a novel water-soluble and reversible fluorescent probe (Flu-Py) was designed and synthesized for the sequentially “ON–OFF–ON” fluorescent detection of Al 3+ and F − in concentration range of 0–10 μmol L −1 and 0–30 μmol L −1 , respectively, with high sensitivity and excellent selectivity. The detection limits for Al 3+ and F − were 0.092 μmol L −1 and 0.112 μmol L −1 , respectively. The binding mode and sensing mechanism of Flu-Py with Al 3+ was verified by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculation. The “ON-OFF–ON” fluorescent property of Flu-Py upon the addition of Al 3+ and F − was utilized for the imaging of living cells. [ABSTRACT FROM AUTHOR]

A Schiff-base compound, 1-(2-hydroxy-5-methylphenylimino)naphthalen-2-ol ( 1b ), has been synthesized and characterized using elemental analysis and different spectroscopic methods. It behaves as highly selective fluorescent chemosensor for Al(III) in 10 mM HEPES buffer in water:methanol (1:9, v/v) (pH 7.2). Fluorescence intensity at 552 nm (excitation at 450 nm) of 1b increases about 200 fold upon addition of 2 equiv. of Al 3+ ion. Quantum yield of 1b increases about 10.8 times upon complex formation with Al 3+ . 1b forms complex with Al 3+ in 1:1 ratio as supported by Job's plot analysis and mass spectroscopic measurement. Chelation enhanced fluorescence of 1b in the presence of aluminum(III) ion is evidenced from large decrease in nonradiative rate constant and high binding constant value. The probe molecule has been applied in living cell imaging study. [ABSTRACT FROM AUTHOR]

A new simple “off–on fluorescence type” chemosensor 1 (2-( N -(2-hydroxyethyl)- N -((pyridin-2-yl)methyl)amino)- N -(quinolin-8-yl)acetamide) has been synthesized for Zn 2+ . The sensor 1 comprises of the quinoline as fluorophore and the 2-((pyridin-2-yl)methylamino)ethanol as both binding site and water-soluble functional group. 1 showed a remarkable fluorescence enhancement in the presence of Zn 2+ in aqueous solution, which was reversible with the addition of ethylenediaminetetraacetic acid (EDTA). The detection limit (0.02 μM) of 1 for Zn 2+ is far lower than World Health Organization guideline (76 μM) in drinking water. Importantly, the chemosensor 1 could be used to detect and quantify Zn 2+ in living cells and water samples. Moreover, the sensing mechanism was supported by theoretical calculations. Therefore, this sensor has the ability to be a practical system for monitoring Zn 2+ concentrations in biological and aqueous samples. [ABSTRACT FROM AUTHOR]