Synthesis of anionic chemodosimeters based on silylated pyridinium N-phenolate betaine dyes

Three novel silylated pyridinium N-phenolate betaine dyes were synthesized and characterized. These compounds were used in acetonitrile as anionic chemodosimeters for the colorimetric detection of F- and CN-. In addition, the system was made highly selective to CN- in relation to other anions in acetonitrile/water mixtures. The nucleophilic attack of the anion on the silicon center of the chemodosimeters, through a nucleophilic substitution at silicon (S(N)2@Si), immediately breaks the Si-O bond, with the formation of their corresponding colored pyridinium N-phenolate betaine dyes as the leaving groups. Thus, this process is effective for the detection of F- and CN-, which are strongly nucleophilic analytes in anhydrous acetonitrile. Fluoride is strongly hydrated when water is present in the medium, this being the reason for the pronounced reduction in the selectivity of this anion in comparison with CN-. (C) 2015 Elsevier Ltd. All rights reserved.