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A simple and efficient anionic chromogenic chemosensor based on 2,4-dinitrodiphenylamine in dimethyl sulfoxide and in dimethyl sulfoxide-water mixtures.
Marini, Vanderléia Gava; Zimmermann, Lizandra Maria; Machado, Vanderlei Gageiro.
Afiliação
  • Marini VG; Departamento de Química, Universidade Regional de Blumenau, FURB, CP 1507, Blumenau, SC 89010-971, Brazil.
Spectrochim Acta A Mol Biomol Spectrosc ; 75(2): 799-806, 2010 Feb.
Article em En | MEDLINE | ID: mdl-20042363
Solutions of 2,4-dinitrodiphenylamine (1) in dimethylsulfoxide (DMSO) are colorless but upon deprotonation they become red. Addition of various anionic species (HSO(4)(-), H(2)PO(4)(-), NO(3)(-), CN(-), CH(3)COO(-), F(-), Cl(-), Br(-), and I(-)) to solutions of 1 revealed that only CN(-), F(-), CH(3)COO(-), and H(2)PO(4)(-) led to the appearance of the red color in solution. The presence of increasing amounts of water in solutions containing 1 made it progressively selective toward CN(-) and the system with the addition of 4.3% (v/v) of water was highly selective for CN(-) among all anions studied. The experimental data collected indicated that proton transfer from 1 to the anion occurs, and a model was used to explain the experimental results, which considers two 1:anion stoichiometries, 1:1 and 1:2. For the latter, the data suggest that the anion forms firstly a hydrogen-bonded complex with a second anion equivalent necessary for the abstraction of the proton, with the formation of a [HA(2)](-) complex. The study performed here demonstrates the important role of the environment of the anion and 1 for the efficiency of the chromogenic chemosensor. Besides the different affinities of each anion for water, the solvation of both the anion and 1 is responsible for reducing the interaction between these species. In small amounts, water or hydrogen-bonded DMSO-water complexes are able to stabilize the conjugated base of 1 through hydrogen bonding, making 1 more acidic, which explains the change from 1:1 and 1:2 toward 1:1 1:anion stoichiometry upon addition of water. In addition, water is able to solvate the anion and also 1, which hinders the formation of 1:1 hydrogen-bonded 1:anion complexes prior to the abstraction of the proton.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Água / Técnicas Biossensoriais / Dimetil Sulfóxido / Compostos Cromogênicos / Ânions Idioma: En Revista: Spectrochim Acta A Mol Biomol Spectrosc Assunto da revista: BIOLOGIA MOLECULAR Ano de publicação: 2010 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Água / Técnicas Biossensoriais / Dimetil Sulfóxido / Compostos Cromogênicos / Ânions Idioma: En Revista: Spectrochim Acta A Mol Biomol Spectrosc Assunto da revista: BIOLOGIA MOLECULAR Ano de publicação: 2010 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido