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Issue 15, 2017
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Bifunctional colorimetric chemosensing of fluoride and cyanide ions by nickel-POCOP pincer receptors

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Abstract

Three Ni(II)-POCOP pincer complexes [NiCl{C6H2-4-OH-2,6-(OPPh2)2}], 1; [NiCl{C6H2-4-OH-2,6-(OPtBu2)2}], 2 and [NiCl{C6H2-4-OH-2,6-(OPiPr2)2}], 3 were studied as bifunctional molecular sensors for inorganic anions and acetate. In CH3CN, fluoride generates a bathochromic shift with a colorimetric change for 1–3 with a simultaneous fluorescence turn on, this optical effect is based on deprotonation of the para-hydroxy group of the POCOP ligand. On the other hand, in a neutral aqueous solution of 80 vol% CH3CN, additions of cyanide produce a distinct change of color by forming very stable complexes with the nickel-based receptors 1–3 with log Ka in the range of 4.38–5.03 M−1 and pronounced selectivity over other common anions such as iodide, phosphate, and acetate. Additionally, bromide shows a modest spectral change and affinity, but lower than those observed for cyanide. On the basis of 1H NMR experiments, UV-vis titrations, ESI-MS experiments, and the crystal structure of the neutral bromo complex of 1, it is proposed that the colorimetric change involves an exchange of chloride by CN on the Ni(II) atom. The Ni(II)-based sensor 1 allows the fluorescent selective detection of fluoride with a limit of 5.66 μmol L−1 and colorimetric sensing of cyanide in aqueous medium in the micromolar concentration range.

Graphical abstract: Bifunctional colorimetric chemosensing of fluoride and cyanide ions by nickel-POCOP pincer receptors

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Publication details

The article was received on 29 Dec 2016, accepted on 22 Feb 2017 and first published on 23 Feb 2017


Article type: Paper
DOI: 10.1039/C6DT04897H
Citation: Dalton Trans., 2017,46, 4950-4959
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    Bifunctional colorimetric chemosensing of fluoride and cyanide ions by nickel-POCOP pincer receptors

    M. K. Salomón-Flores, I. J. Bazany-Rodríguez, D. Martínez-Otero, M. A. García-Eleno, J. J. Guerra-García, D. Morales-Morales and A. Dorazco-González, Dalton Trans., 2017, 46, 4950
    DOI: 10.1039/C6DT04897H

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