Abstract

NICOLETI, Celso R.; MARINI, Vanderléia G.; ZIMMERMANN, Lizandra M.  and  MACHADO, Vanderlei G.. Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol. J. Braz. Chem. Soc. [online]. 2012, vol.23, n.8, pp. 1488-1500.  Epub Aug 07, 2012. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532012005000007.

4-(4-Nitrobenzylideneamine)phenol was used in two strategies allowing the highly selective detection of F^- and CN^-. Firstly, the compound in acetonitrile acts as a chromogenic chemosensor based on the idea that more basic anions cause its deprotonation (colorless solution), generating a colored solution containing phenolate. The discrimination of CN^- over F^- was obtained by adding 1.4% water to acetonitrile: water preferentially solvates F^-, leaving the CN^- free to deprotonate the compound. Another strategy involved an assay comprised of the competition between phenolate dye and the analyte for calix[4]pyrrole in acetonitrile, a receptor highly selective for F^-. Phenolate and calix[4]pyrrole form a hydrogen-bonded complex, which changes the color of the medium. On the addition of various anions, only F^- was able to restore the original color corresponding to phenolate in solution due to the fact that the anion dislodges phenolate from the complexation site.

Keywords : anionic chromogenic chemosensor; displacement assay; naked-eye detection; anion sensing; calix[4]pyrrole.