RESUMO

Films of three polymers, based on ethyl(hydroxyethyl)cellulose functionalized with protonated perichromic dyes, were used for anion sensing. The polymer functionalized with protonated Brooker's merocyanine acts as a chromogenic/fluorogenic system for the selective detection of cyanide in water. An increase of >28 times was verified for the fluorescence lifetime of the sensing units in the polymer in comparison with protonated Brooker's merocyanine in water. Moreover, an increase in the pKa values was verified for the sensing units in the polymers. Data suggest that the hydrocarbonic polymeric chains provide an adequate microenvironment to protect the sensing unit from bulk water. The other polymer, functionalized with an iminophenol, also showed high selectivity for cyanide (detection limit=9.36×10-6molL-1 and quantification limit=3.12×10-5molL-1). The polymer functionalized with azophenol units is unable for the detection of cyanide, due to the low pKa value verified for its chromogenic units.