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Two novel fluorescent probes ( C1, C2), comprising a coumarin moiety as fluorophore and a pair of dithiocarbamates as recognition sites, were designed and synthesized as fluorescent probes for Ag. The probes exhibited high selectivity for Ag with fluorescence enhancement (FE) in CHCN/4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (1:9, v/v, pH 7.38); the selectivity was not affected by other metal ions. The binding ratio of C2-Ag complex was determined to be 1:1 according to the Job plot and mass spectroscopy (MS) data. The association constant K of Ag with C2 was 1.6 × 10 M. These probes could be applied for monitoring of Ag in aqueous solution in the pH range of 5.0-8.0, with calculated detection limit of 0.27 μM. [ABSTRACT FROM AUTHOR]

A thioether-functionalized probe with a dipodal pyrene-sulfonamide fluorophore (probe 1 ) was synthesized for the selective and sensitive detection of Hg 2+ in aqueous solutions. In addition, a probe with a monopod pyrene-sulfonamide unit was prepared (probe 2) . Among various metal ions, these two probes appeared to selectively bind to Hg 2+ at a 1:1 ratio, with a stronger association of probe 1 than probe 2 , as evidenced by titration experiments. The green emission displayed by probe 1 was completely quenched by the coordination of Hg 2+ to sulfur ( ON-OFF ), presumably via energy transfer from the pyrene fluorophore to the [sulfur-Hg 2+ ] unit. The limit of detection (LOD) was 1 nM (0.22 ppb), one of the lowest values obtained so far. Furthermore, the in situ -prepared [ 1 +Hg 2+ ] complex continued to be utilized to selectively detect dithiouracil (DTU) via an “ OFF-ON” mechanism among diverse biomolecules, along with an LOD of 20 nM. Thus, probe 1 alone or together with Hg 2+ allowed the cascade detection of Hg 2+ and DTU with high selectivity and ultra-sensitivity. The current study indicates that probe 1 not only serves as an ‘INHIBIT and AND’ logic gate, but also works as an “ ON−OFF−ON” molecular switch triggered by the sequential addition of Hg 2+ and DTU. [ABSTRACT FROM AUTHOR]

A novel fluoroionophore compound was synthesized from a boron dipyrromethene (BODIPY) fluorophore and 4′-formylbenzo-15-crown-5 ionophore groups. Photophysical properties of the BODIPY-crown compound were studied with UV-Vis and fluorescence spectroscopy. The effect of metalic cations (Li, Na, K, Mg, Ca, Ba, Al, Fe, Cu, Co, Zn, Ag, Hg, Pb) on the absorption and fluorescence spectra of compound 2 was investigated. Blue shifts were detected in UV-Vis spectra upon addition of some metal ions (Al > Fe > Na). At the same time, the emission intensity of this complex increased due to binding of Na ion to the benzo crown cavity. Additionally, a decrease in the intensity of the 630 nm emission peak and an increase in the intensity of the 570 nm emission peak was observed in the fluorescence emission spectra following addition of Al and Fe ions. [ABSTRACT FROM AUTHOR]

A novel reactive fluorescent dye [2-morpholine-4-(6-chlorine-1,3,5-s-triazine)-amino]fluorescein based on 5-aminofluorescein was synthesized by electrophilic substitution. The photophysical properties, solvent effect, pH value sensitivity, and metal ions responsibility of this new fluorophore were investigated. Compared with 5-aminofluorescein, the novel fluorophore exhibited stronger fluorescence and longer lifetime. The fluorescence property of the new dye was obviously affected by different solvents and pH values, and it showed stronger fluorescence in the protic solvents or an alkaline environment. Moreover, the fluorescent intensity could be enhanced by the formation of complex with metal ions especially with Mg2+. The results show that the fluorescent dye is a promising efficient sensor for solvents, protons, and metal ions. [ABSTRACT FROM AUTHOR]

We report the design and synthesis of a novel styrylbenzothiazolium ( 3 ) derivative developed as a fluorescent and colorimetric chemodosimeter with high selectivity toward Hg 2+ , CN − and OH − ions. An obvious loss of pink color in the presence of Hg 2+ and CN − ions could make it a suitable “naked eye” indicator. We propose a sensing mechanism whereby the benzenoid form is changed to a quinoid form upon Hg 2+ binding in a 1:1 stoichiometric ratio. More significantly, the styrylbenzothiazolium-Hg 2+ and styrylbenzothiazolium-CN − complexes exhibited a dual-channel chromo-fluorogenic response. The sensors exhibit remarkable Hg 2+ -, CN − -, and OH − -selective red fluorescence but remain dark-green in the presence of a wide range of tested metal ions and anions. [ABSTRACT FROM AUTHOR]

A novel fluorescein-rhodamine dyad probe has been synthesized and its chemosensory applications are explored. Anion and cation specific responses of the probe permit ratiometric detection of Hg 2+ and fluoride ions, individually and collectively, with different fluorescence outputs. The presence of other commonly coexistent ions does not affect the Hg 2+ and fluoride ion detection ability of the probe. The probe is highly sensitive to Hg 2+ and fluoride ions and it can detect Hg 2+ and fluoride ions even at ppb level concentrations. The probe is non-toxic under the experimental conditions, cell permeable and useful for the imaging of intracellular Hg 2+ and fluoride ions. [ABSTRACT FROM AUTHOR]

Recently, more and more rhodamine derivatives have been used as fluorophores to construct sensors due to their excellent spectroscopic properties. A rhodamine-based fluorescent and colorimetric Fe3+ chemosensor 3',6'-bis(ethylamino)-2-acetoxyl-2',7'-dimethyl-spiro[1 H-isoindole-1,9'-[9 H]xanthen]-3(2 H)-one ( RAE) was designed and synthesized. Upon the addition of Fe3+, the dramatic enhancement of both fluorescence and absorbance intensity, as well as the color change of the solution, could be observed. The detection limit of RAE for Fe3+ was around 7.98 ppb. Common coexistent metal ions showed little or no interference in the detection of Fe3+. Moreover, the addition of CN− could quench the fluorescence of the acetonitrile solution of RAE and Fe3+, indicating the regeneration of the chemosensor RAE. The robust nature of the sensor was shown by the detection of Fe3+ even after repeated rounds of quenching. As iron is a ubiquitous metal in cells and plays vital roles in many biological processes, this chemosensor could be developed to have applications in biological studies. [ABSTRACT FROM AUTHOR]

A new bipyridyl derivative 1 bearing rhodamine B as visible fluorophore was designed, synthesized and characterized as a fluorescent and colorimetric sensor for metal ions. Interaction with Cu2+, Zn2+, Cd2+, Hg+, and Hg2+ ions was followed by UV/Vis and emission spectroscopy. Upon addition of these metal ions, different colorimetric and fluorescent responses were observed. 'Off-on-off' (Cu2+, Zn2+, and Hg2+) and 'off-on' (Hg+ and Cd2+) systems were obtained. Probe 1 was explored to mimic XOR and OR logic operations for the simultaneous detection of Hg+-Cu2+ and Hg+-Zn2+ pairs, respectively. DFT calculations were also performed to gain insight into the lowest-energy gas-phase conformation of free receptor 1 as well as the atomistic details of the coordination modes of the various metal ions. [ABSTRACT FROM AUTHOR]

Highlights: [•] A PAMAM light-harvesting dendron of second generation, core and peripherally functionalized with Rhodamine 6G and 1,8-naphthalimide fluorophores is synthesized. [•] The yellow-green emitting periphery of the antenna is designed as a PET based fluorescence probe. [•] The system manifests excellent selective response to protons over representative metal ions in aqueous medium. [•] Core emission intensity of the systems is enhanced by over an order of magnitude as a function of pH. [•] The wavelength-shifting bichromophoric system acts as a highly selective ratiometric fluorescent pH probe in complex samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] Designed and synthesized a new dicoumarol-based fluorescent compound. [•] Crystal structure analyses and discussion for the compound. [•] The compound exhibits a highly fluorescence-quenching selectivity for FeIII. [Copyright &y& Elsevier]