title: Bifunctional colorimetric chemosensing of fluoride and cyanide ions by nickel-POCOP pincer receptors.
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 Kain the range of 4.38-5.03 M-1and 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 of1H 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-1and colorimetric sensing of cyanide in aqueous medium in the micromolar concentration range.
authors.affiliation: Centro Conjunto de Investigación en Química Sustentable, UAEM-UNAM, C. P. 50200, Toluca, Estado de México, México, Instituto de Química, Universidad Nacional Autónoma de México.
authors.forename: María K
authors.initials: MK
authors.lastname: Salomón-Flores
authors.forename: Iván J
authors.initials: IJ
authors.lastname: Bazany-Rodríguez
authors.forename: Diego
authors.initials: D
authors.lastname: Martínez-Otero
authors.forename: Marco A
authors.initials: MA
authors.lastname: García-Eleno
authors.forename: Jorge J
authors.initials: JJ
authors.lastname: Guerra-García
authors.forename: David
authors.initials: D
authors.lastname: Morales-Morales
authors.forename: Alejandro
authors.initials: A
authors.lastname: Dorazco-González