A new multifunctional benzimidazole tagged coumarin as ratiometric fluorophore for the detection of Cd2+/F- ions and imaging in live cells.

A novel multifunctional ratiometric fluorescent probe has been designed and synthesized for the selective recognition of Cd2+/F- ions. The probe (3)-((2)-(1H-benzoimidazole-2-yl)-phenylimino) methyl-4-chloro-methyl-2H-chromen-2-ene (BIMC) displays excellent ratiometric responses towards Cd2+/F- ions over the tested cations/anions. The lowest detection limits observed for Cd2+ and F- are 1.5 × 10-10 mol/l and 1.2 × 10-10 mol/l respectively. Job's plot and Electro spray Ionization mass spectral (ESI-MS) studies confirms 1:1 binding stoichiometry of BIMC with Cd2+/F- ions, which is further evidenced by 1H NMR titration studies. The reversibility studies of BIMC with Cd2+ have been investigated using ethylenediaminetetraacetic acid (EDTA). Upon binding to Cd2+/F- ions, the probe features strong ratiometric response in both UV-Visible and fluorescence spectra due to the inhibition of intramolecular charge transfer (ICT). Furthermore, the mechanism of ICT has been rationalized via solvatochromism and DFT calculations.

Charge transfer based "turn-on" chemosensor for Zn²âº ion recognition using new triaryl pyrazoline derivative.

The fluoroionophore PY serves as a selective and fluorimetric chemosensor for Zn(2+) based on charge transfer (CT). A mechanism for the binding mode was proposed based on fluorescence changes, NMR experiments and theoretical calculations. The 1:1 stoichiometry between Zn(2+) and the sensor was deduced from Job's plot. The addition of EDTA quenches the fluorescence of PY.Zn(2+) complex offers PY as a reversible chemosensor.

Novel indole based dual responsive "turn-on" chemosensor for fluoride ion detection.

An efficient new dual channel chemosensor 2,3-bis((E)-(1H-indole-3-yl)methyleneamino)maleonitrile (DN) which exhibits selective sensing of F(-) ions in DMSO, was synthesized by a facile one step condensation reaction of indole-3-carboxaldehyde with diaminomaleonitrile. The probe DN was characterized by elemental analysis, (1)H, (13)C-NMR, ESI-MS and IR spectral techniques. Upon addition of F(-), DN induces remarkable changes in both absorption and fluorescence spectra on the basis of charge transfer mechanism. The receptor DN serves for highly selective, sensitive detection of F(-) without the interference of other relevant anions. The Job's plot analysis indicates the binding stoichiometry to be 1:1 (host/guest).

Aminobenzohydrazide based colorimetric and 'turn-on' fluorescence chemosensor for selective recognition of fluoride.

Chemosensors based on aminobenzohydrazide Schiff bases bearing pyrene/anthracene as fluorophores have been designed and synthesized for F(-) ion recognition. The addition of fluoride ions to the receptors causes a dramatically observable colour change from pale yellow to brown/red. (1)H NMR studies confirm that the F(-) ion facilitates its recognition by forming hydrogen bond with hydrogens of amide and amine groups. Moreover these sensors have also been successfully applied to detection of fluoride ion in commercial tooth paste solution.

Triazole based ratiometric fluorescent probe for Zn2+ and its application in bioimaging.

An efficient fluorescent chemosensor 4-((2-hydroxynaphthalen-1-yl)methyleneamino)-3-phenyl-1H-1,2,4-triazole-5(4H)-thione, based on triazole has been designed by condensing 2-hydroxy-1-napthaldehyde with amine, appended to 1,2,4-triazole unit. The probe displays excellent selectivity and sensitivity in both absorbance and fluorescence detection of Zn2+ over other essential metal ions. The nature of fluorescence behavior of receptor upon addition of Zn2+ has been obtained from Density Functional Theory calculations. Imaging experiment indicates that probe works effectively for intracellular Zn2+ imaging with good cell permeability and biocompatibility.