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A novel NIR probe based on oxazolonaphthoimidazo[1,2- a ]pyridine-malononitrile (ONIM) conjugate linked by vinyl linkage was designed and synthesized for the detection of cyanide ion. [Display omitted] • An orange emitting sensor ONIM (712 nm) with D-π-A framework is synthesized. • The ONIM emission is retained in the solid state. • ONIM could sense cyanide ion without interference of other anions. • Sensing mechanism of cyanide sensing was confirmed by 1H NMR and DFT calculations. • Live cell imaging in human breast cancer cell MDA-MB 231 and as solid state sensor was achieved. Cyanide is undoubtedly dangerous and fast acting chemical employed in various industrial applications with toxic side effects, which raises urgent need for its monitoring. In this context, oxazolonaphthoimidazo[1,2- a ]pyridine-malononitrile (ONIM) conjugate linked by vinyl linkage was designed, synthesized and characterised by FT-IR, NMR and mass spectrometry. The developed probe has been evaluated for the colorimetric and fluorometric detection of cyanide ion. An obvious color change with unique rapid " turn-off " fluorometric response was observed within 5 s upon addition of CN– thus reflecting its better acuteness and sensitivity over other competing anions. The developed probe exhibits a detection limit of 9.54 nM which is very low in comparison to maximum permitable amount of cyanide in drinking water (1.9 µM). The probe is stable within the p H range of 2–9 and suitable for the recognition of CN– in the p H range of 7 to 10, specially at neutral p H conditions. The chemodosimetric approach based detection mechanism was authenticated by 1H NMR titration and DFT calculations. The solid state applications were established by utilising ONIM impregnated TLC plates and filter paper in cyanide recognition. The solid state emissive behaviour of ONIM offers on-spot detection of the cyanide anion. Additionally, the practicability of ONIM has been extended in live cell imaging of CN– in human breast cancer cell (MDA-MB-231), which revealed a " turn-off " fluorescence response for the probe in the presence of CN– ion. [ABSTRACT FROM AUTHOR]

A Rhodamine B- quinoline conjugate ( RSQ ) functions as a colorimetric and fluorescence probe for selective recognition of Bi 3+ ion based on CHEF assisted FRET process. RSQ visibly changes its colour and fluorescence profile upon addition of Bi 3+ ion. The distinctive colour change allows facile discrimination of Bi 3+ over other common cations. Lowest concentration of Bi 3+ detected by RSQ is 0.05 μM. RSQ efficiently images intracellular Bi 3+ in live SiHa cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Schiff base molecule (L) having pyrene and coumarin moieties was synthesized. • L is highly selective colorimetric and fluorometric probe for Al(III), Cr(III) and Fe(III) with very low detection limit. • Fluorescence response is an "OFF-ON" mechanism through inhibition of PET and operation CHEF processes. • Cell imaging and cytotoxicity studies performed using MDA-MB-231 and HDF cells indicate that L is biologically safe. A Schiff base (L) containing coumarin and pyrene moieties was synthesized and characterized. It showed excellent selective recognition of M(III) ions (M = Al, Cr and Fe) in presence of monovalent, divalent and other trivalent metal ions. Sensor L itself is non-fluorescent upon excitation with 353 nm light (λ ex = 353) but a very large enhancement in fluorescence intensity was observed during the addition of these three trivalent metal ions into a CH 3 OH/aqueous HEPES buffer (5 mM, pH = 7.4, 6:4, v/v) solution of L. This prominent "OFF-ON" fluorescence switching can be observed with naked eye, in which "OFF" is due to operation of PET process in free L but PET is inhibited upon complexation thereby allowing CHEF (chelation enhanced fluorescence) process to operate. Detection limits of Al3+, Cr3+ and Fe3+ using L have been found to be 0.79 nM, 1.15 μM, and 1.28 μM respectively in the pH range of 6‒10. Additionally, "OFF-ON" fluorescence can be reversed by sequestering M(III) ions using [EDTA]4– solutions. Analysis of mass spectra and Job's plot revealed a binding ratio of 1:1 for all three metal ions with L. The imine nitrogen and carbonyl oxygen atoms of L are involved in binding with Al3+, Cr3+ and Fe3+ ions, as revealed by NMR titration and IR spectroscopic analysis. Results of quantum yield (Φ), time resolved photoluminescence (TRPL) and computational studies (DFT/TDDFT) studies were also reported. Fluorescence intensity of these M(III) bound L complexes is quenched by fluoride ions. From cytotoxicity analysis, 7.5 μM of probe L was selected to analyze its fluorescence attributes in cellular imaging. Using human breast cancer cell line (MDA-MB-231) and primary human dermal fibroblasts (HDF), the potentiality of the probe L was confirmed through fluorescence cell imaging experiments. [ABSTRACT FROM AUTHOR]