title: A selective redox and chromogenic probe for Hg(II) in aqueous environment based on a ferrocene-azaquinoxaline dyad.
abstract: A new chemosensor molecule 4 based on a ferrocene-azaquinoxaline dyad effectively recognizes Hg(2+) in an aqueous environment as well as Pb(2+) and Zn(2+) metal cations in CH(3)CN solution through three different channels. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red shift (Deltalambda = 112-40 nm) of the low energy band, in their absorption spectra, is produced. These changes in the absorption spectra are accompanied by color changes from orange to deep green, for Hg(2+), and to purple in the cases of Pb(2+) and Zn(2+). Remarkably, the redox and colorimetric responses toward Hg(2+) are preserved in the presence of water (CH(3)CN/H(2)O, 3/7). The emission spectrum of 4 in CH(3)CN (lambda(exc) = 270 nm) undergoes important chelation enhancement of fluorescence (CHEF) in the presence of Hg(2+) (CHEF = 204), Pb(2+) (CHEF = 90), and Zn(2+) (CHEF = 184) metal cations. Along with the spectroscopic data, the combined (1)H NMR data of the complexes and the theoretical calculation suggest the proposed bridging coordination modes.
authors.affiliation: Departamento de Química Orgánica, Facultad de Química, Campus de Espinardo, Universidad de Murcia, E-30100 Murcia, Spain.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Zapata
authors.forename: Antonio
authors.initials: A
authors.lastname: Caballero
authors.forename: Arturo
authors.initials: A
authors.lastname: Espinosa
authors.forename: Alberto
authors.initials: A
authors.lastname: Tárraga
authors.forename: Pedro
authors.initials: P
authors.lastname: Molina
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D001372:Aza Compounds / Q000737:chemistry*; D002863:Chromogenic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D003124:Colorimetry; D005296:Ferrous Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D007854:Lead / Q000737:chemistry; D008628:Mercury / Q000737:chemistry*; D000075163:Metallocenes; D056004:Molecular Dynamics Simulation; D010084:Oxidation-Reduction; D011810:Quinoxalines / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D001372:Aza Compounds; D002863:Chromogenic Compounds; D005296:Ferrous Compounds; D005456:Fluorescent Dyes; D000075163:Metallocenes; D011810:Quinoxalines; D014867:Water; D007854:Lead; D008628:Mercury; D015032:Zinc; C004998:ferrocene