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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]

A supramolecular ligand for the specific detection of Cd 2+ ions, [pyridine-2,6-diylbis (methyleneimino-2,1-phenylene)]bis(phenyl methanone) ( L ) was synthesized, and characterized by various spectral techniques and single crystal X-ray crystallography. The L exhibits “turn-on” fluorescence and excellent selectivity towards Cd 2+ ions in acetonitrile/HEPES buffer medium (1:5 v/v). The lowest quantum yield and shorter emission lifetime of L (Φ = 0.0293, τ = 9.98 ns) was corroborated by the operation of PET process. This PET is quenched during the complex formation between L and Cd 2+ leads to high quantum yield and longer emission lifetime (Φ = 0.1770, τ = 13.46 ns). The L forms 1:1 complex with Cd 2+ is confirmed by Job’s plot and ESI-Mass techniques. The binding of L with Cd 2+ was studied by UV–vis and NMR. The reversible of L.Cd 2+ with EDTA establishes the reuse of L. The lower detection limit of L was found to be 10.21 nM. The impact of fluorescence with respect to pH, time, temperature and solvent concentrations was investigated to find its practical applications. The sensor was applied for the determination of Cd 2+ ions in water samples. DFT studies explain the binding mechanism between the L and Cd 2+ . The cell imaging studies established that L has been used to detect the intracellular Cd 2+ ions in HeLa cells. [ABSTRACT FROM AUTHOR]

An efficient fluorescein based probe (H 2 L) for the dual sensing of Al 3+ and Cu 2 + has been synthesized and characterized. H 2 L was highly selective toward these two ions with different fluorescence signals and binding modes in two different media. In EtOH-H 2 O (3:2, v/v; pH 4.0), H 2 L selectively binds Al 3+ to form a 1:1 ligand/metal complex, giving rise to a visible pale pink-to-yellow color change and fluorescence enhancement at 440 nm, while in CH 3 CN-H 2 O (2:3, v/v; pH 7.2), H 2 L and Cu 2+ form a 1:2 ratio complex, resulting in a color change from pink to orange-yellow and a significant fluorescence enhancement at 520 nm. The binding modes were confirmed by fluorescence, absorption, IR, ESI-MS and 1 H NMR titrations. The detection limits were calculated to be 7.32 × 10 −8 M and 1.47 × 10 −8 M for Al 3+ and Cu 2+ , respectively. Cell imaging studies demonstrate that this sensor is capable of sensing Al 3+ and Cu 2+ in living cells. [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 novel aggregation-induced emission (AIE) active linear conjugated bis-Schiff base compound, ( E )- N , N ′-bis(4-( Z )-2-(4-butoxyphenyl)-1-cyanovinylphenyl)-1,4-benzenebismethaneimine ( 4 ) containing α-cyanostilbene unit was designed, synthesized and characterized. The distinct change of color and/or fluorescence emission of 4 + Hg 2+ in tetrahydrofuran (THF) and THF/water solution provided a simple and easy discrimination way for Hg 2+ by “naked eye” or using a UV lamp. The aggregating patterns of 4 were applied to explain the mechanism of sensing. The as-synthesized sample showed comparatively high selectivity and sensitivity to Hg 2+ through fluorescence “turn-on” response with a low detection limit (3.4 × 10 −9 M in THF, 2.4 × 10 −7 M in THF/water). The results implied that the as-made sample could effectively act as Hg 2+ sensor not only in THF and THF/water but in living cells. [ABSTRACT FROM AUTHOR]

Many rhodamine B probes for metal ions and anions showing “orange” fluorescent have attracted a tremendous amount of attention. Herein a rhodamine B-based fluorescent probe 1 showing “green” fluorescence emission in the presence of Hg 2+ was first reported. Self-assembled aggregation was proved to be the crucial factor for the green emitting fluorescence by means of resonance light scattering spectra, fluorescence spectra, ESI mass spectral analysis and SEM image. The probe 1 was developed as a excellent Hg(II)-selective green fluorescence agent in ethanol/HEPES buffer media (v/v = 3:7, pH 7.3) with a detection limit of 0.09 μM. Meanwhile, the green fluorescence of 1 -Hg 2+ can be quenched severely by Cys but not for GSH, S 2− , SO 4 2− , SO 3 2− , CN − , CO 3 2− and HCY. The sequential switching effect for Hg 2+ and then Cys has been achieved in aqueous media and bioimaging with satisfactory results. [ABSTRACT FROM AUTHOR]

A chemosensor 3-[(2-hydroxybenzylidene)-amino]-1H-pyridin-2-one (HL) for multi-ions was synthesized and characterized by single-crystal X-ray diffraction. HL is a turn-on fluorescence chemosensor for Al 3+ , F − , and CN − ions in DMSO. F − and CN − anions could be further distinguished by the ratiometric absorption spectrometry method. Job plot and 1 H NMR data showed that the binding stoichiometries of HL with Al 3+ , F − , or CN − all were 1:1. Further observations of 1 H NMR titration and ESI-MS showed that the possible fluorescent species of Al 3+ with HL was [AlL(OH)(DMSO) 2 ] + in DMSO. The spectroscopic observations of the Al(III) complex showed that the two oxygen atoms and one imine nitrogen atom of HL were coordinated to the Al(III) ion. While the crystal structure of the Ni(II)-L complex confirmed the tridentate coordination mode of HL in the complexes. The experimental results revealed that HL and F − ion formed hydrogen bond in DMSO, while CN − attacked the carbon atom at –C N of HL to undergo a nucleophilic addition. The theoretical calculations confirmed that HL showed very weak fluorescence because of the excited-state intramolecular proton transfer (ESIPT). The turn-on sensing of HL to Al 3+ , F − , and CN − ions arose from the inhibition of ESIPT. MTT tests showed that HL was low toxic to cells. Also, HL could probe intracellular Al 3+ and F − ions by bioimaging. [ABSTRACT FROM AUTHOR]

A novel 4-amino-1,8-naphthalimide-based fluorescent Cd 2+ sensor with phenyliminoethoxy-ethoxyoxyacetic acid as receptor, was developed and applied successfully to image Cd 2+ in living cells. It demonstrates high selectivity and sensitivity for sensing Cd 2+ with about 24-fold enhancement in aqueous solution. Particularly, it is high selectivity against Zn 2+ . [ABSTRACT FROM AUTHOR]

Two new quinoline hydrazones were synthesized, characterized and investigated as reversible ratiometric fluorescence pH sensors in the acidic pH region. The sensors were designed by the formation of simple donor-acceptor couple of quinoline aldehyde and phenyl hydrazine where protonation of quinoline-N triggered the pH sensing. No significant interference on emission behavior was observed in the presence of various metal ions. The sensors were used to visualize HeLa cells both at acidic and neutral pH with different emission. The MTT assay revealed negligible toxicity for both the hydrazones. The spectral properties, especially the large Stokes shift and the geometry of the molecules at the ground and excited states had been rationalized through DFT and TDDFT studies. [ABSTRACT FROM AUTHOR]

Abstract: A new coumarin derivative (MS1) containing an imine moiety and a hydroxyl moiety exhibits an enhanced fluorescence in the presence of Hg2+ ions. Other metal ions Al3+, Ca2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+ produced only minor changes in the fluorescence values of MS1. The binding ratio of MS1–Hg2+ complexes was determined from the Job plot to be 1:1. The binding constant (K a) of Hg2+ binding to MS1 was found to be 6.85×103 M−1. The maximum fluorescence enhancement caused by Hg2+ binding to MS1 was observed in the pH range of 6.5–9.0. Confocal fluorescence microscopy imaging using RAW 264.7 cells showed that MS1 could be used as an effective fluorescent probe for detecting Hg2+ in living cells. [Copyright &y& Elsevier]

Abstract: A naphthalimide-based water soluble Zn2+ sensor bearing polyamino carboxylate as a metal chelating moiety was synthesized and its application for the selective detection of Zn2+ ion in 100% aqueous solution is demonstrated. The newly developed fluorescent sensor exhibits selective binding affinity towards Zn2+ and pH insensitivity in biologically relevant range. Confocal fluorescent microscopy images indicate that this probe works effectively for intracellular Zn2+ imaging with high cell permeability. [Copyright &y& Elsevier]