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The sensor MH-4 has a high sensitivity and selectivity to Cu2+ over a wide range of other metal ions in acetonitrile (ACN)/water (v/v 1:1). The fluorescence imaging studies demonstrated the permeability of MH-4 in L929 living cells and the sensing of Cu2+ in the cells. [Display omitted] • A diformyl phenol based optical sensor (MH-4) was developed for the detection of Cu2+. • MH-4 showed high selectivity and sensitivity Cu2+ over other metal ions/anions tested. • MH-4 can detect Cu2+ at nanomolar level. • Mh-4 is suitable for imaging Cu2+ in living cells. Given the critical role of trace copper ion in human health, its sensitive detection in environmental and biological samples is crucial. We, herein, designed and synthesized a diformyl phenol-based turn-off fluorescent sensor ((5-(tert -butyl)-2-hydroxy-1,3-phenylene)bis (methanylylidene)) bis (azanylylidene)) bis(4-hydroxy-2H-chromen-2-one) (MH-4)) for the spectrofluorometric detection of Cu2+ ion, which has sensitive and selective fluorescence quenching over other competitive metal ions. The efficiency and fast response of the sensor were confirmed by UV–Visible, fluorescence spectral changes, which may be due to the formation of coordination bond between MH-4 and Cu2+ ions. The binding stoichiometry of MH-4 with Cu2+ was examined with the help of UV–Vis and fluorescence titrations, and Job's plot, which gives a 1:1 coordination stoichiometry; this is further confirmed through MS studies. The binding constant of the complex was found to be 9.4 x 107 M−1. Then, the absorbance and fluorescence-based detection limits were calculated to define the sensitivity range of the proposed sensor and were found to be 69.30 nM and 37.40 nM, respectively. Finally, a live cell image study of MH-4 in L929 (murine aneuploid fibrosarcoma) cells was also performed to test the cell permeability of MH-4 and its effectiveness for selective detection of Cu2+ in living cells. [ABSTRACT FROM AUTHOR]

A new simple Schiff-base ligand 2-Hydroxy-1-naphthaldehyde-(2-pyridyl) hydrazone (HL) was synthesized and characterized as a fluorescent probe. In aqueous solution containing 10% ethanol (Hexamethylenetetramine-HCl buffer, pH5.3), HL selectively binds Al 3+ to form a 1:1 ligand/metal complex, resulting in a color change from colorless to yellow–green and a significant fluorescence enhancement at 454 nm. The addition of EDTA quenches fluorescence of the HL·Al 3+ complex, indicating that HL serves as a reversible chemosensor for Al 3+ . Under the optimum conditions, the dynamic range of the system was found to be linear up to 4.0 × 10 −6 M Al 3+ ions with a limit of detection of 36.6 nM. The probe is very effective for detection of intracellular Al 3+ through fluorescence microscopic imaging. [ABSTRACT FROM AUTHOR]

A new quinoline functionalized Schiff base ( L ) was synthesized which displayed selective fluorescence response to trivalent metal cations (Al 3+ , Fe 3+ and Cr 3+ ) over a variety of divalent and monovalent metal cations in ∼100% aqueous medium. The specific sensing of trivalent cations by a switch-ON fluorescence response is based on selective acid catalyzed imine bond hydrolysis of L facilitated by the higher valence metal ions in aqueous medium and this mechanism was corroborated by mass spectrometry and density functional theory (DFT) calculations. The developed probe was biocompatible and rendered sensing of trivalent metal ions (Al 3+ , Fe 3+ and Cr 3+ ) in live HeLa cells through imaging. [ABSTRACT FROM AUTHOR]

• Probe FL can display selectivity toward Cu+2 over other ions in DMSO/water (2/8, v/v) and showed an obvious color change. • Probe FL can operate in a wide range of pH. • The living cell image experiments demonstrate probe FL could be used to detect intracellular Cu2+ in living cells. A novel fluorescent and colorimetric probe FL was designed and synthesized for selective Cu2+ detection in aqueous solutions. The detection limit of probe FL for Cu2+ was determined to be 1.09 μM. Furthermore, probe FL was successfully used to recognize Cu2+ in living cells, indicating its high potential in biological imaging applications. [ABSTRACT FROM AUTHOR]