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• Development of a novel red-emitting fluorescent probe (HSA) for the detection of Cys. • The probe can high sensitivity detect Cys with a low LOD. • Successfully verified the experimental results by the theoretical calculation study. • The probe can be used for exogenous Cys monitoring and endogenous Cys cell imaging experiments. Herein, we synthesized a red-emitting fluorescence turn-on probe (HSA) for specific detection of cysteine (Cys) over other biothiols (glutathione (GSH) and homocysteine (Hcy)). The acrylate group was chosen as the recognition site for specific discrimination of Cys. Absorption and emission spectra display a high selectivity towards Cys over GSH/Hcy, organic small-molecule interfering substances and anions, with a high sensitivity towards Cys (0.12 μM) in 1% ethanol-containing PBS buffer solution (25 mM, pH = 7.4). Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were conducted to clarify the luminescence mechanism of the probe. Furthermore, the probe was successfully applied to the determination of free Cys in human serum and the fluorescence imaging of endogenous Cys in living cells. [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]

A novel p -dimethylaminobenzamide-based Schiff base derivative DTBL was synthesized via a simple reaction and utilized as a “turn-on” fluorescent indicator for copper ion (Cu 2+ ). It showed extraordinary high selectivity toward Cu 2+ in MeCN–H 2 O (v/v = 3:2, pH = 5) HOAc-NaOAc buffer solution, and the fluorescence intensity change were noticeable for the Cu 2+ detection even in the presence of different kinds of foreign ions and compounds at very high concentrations. The 2:1 stoichiometry of DTBL-Cu 2+ complex was calculated from Job’s plot based on fluorescence titrations. The good linear relationship easily exhibited a dynamic response range for Cu 2+ from 0 to 3.4 μM and the detection limit (0.32 nM) of DTBL for Cu 2+ was far lower than the maximum allowable level of the WHO limit (30 μM) for drinking water. Moreover, the adaptability of DTBL for biological applications was also demonstrated by fluorescence imaging of intracellular Cu 2+ in living cells. The results indicate that DTBL should be available for the research on the biological and environmental applications associated with Cu 2+ . [ABSTRACT FROM AUTHOR]

A rhodamine derivative ZP1 , appended with two 1,2,3-triazole moieties via a diaminopropyl linker, is a chromogenic and fluorogenic sensor for Zn 2+ . In the presence of Zn 2+ , a colorless solution of ZP1 becomes pink with a maximum absorption of 555 nm and a large fluorescence enhancement (140-fold) at 579 nm (Φ = 0.12). ZP1 is highly selective with Zn 2+ , among other metal ions including Cd 2+ , with a binding constant ( K a ) of 7.4 × 10 3 M −1 and a detection limit of 1 μM (65 ppb). Similar rhodamine derivatives with a shorter linker or with a single triazolyl group cannot function as a Zn 2+ chemosensor. ZP1 is membrane-permeable and could react with intracellular Zn 2+ in cultured HeLa cells. [ABSTRACT FROM AUTHOR]

A new turn-on fluorescent quinolone tetrazole based chemosensor (QT-1) is designed and synthesized which shows high sensitivity and selectivity for Zn 2+ ions in aqueous acetonitrile solution. QT-1 probe easily distinguishes Zn 2+ ions from Cd 2+ ions. Job's plot analysis suggested that the binding of QT-1 and Zn 2+ ions is probably a 1:1 stoichiometry. Thus QT-1 can be employed for fluorescent imaging of Zn 2+ ions in living cells. [ABSTRACT FROM AUTHOR]