Synthesis of a new colorimetric receptor based on calix[4]pyrrole binding oxime for selective recognition of fluoride ions

摘要

A colorimetric anion sensor a-meso-heptaethylcalix[4]pyrrole-meso-3-aminophenyl-p-nitrobenzaldoxime was synthesised and characterised by various spectroscopic techniques. Anion-binding studies were carried out using UV–vis, and ~1H NMR titrations, revealing that the receptor exhibits selective recognition towards F~- over other anions. The selectivity for F~- among the halides is attributed mainly to the hydrogen bond interaction of the receptor with F~-. Receptor showed colour change from colourless to yellow in the presence of tetrabutylammonium fluoride with 1:2 stoichiometry. Cyclic voltammetry studies, carried out in CH_3CN, provided evidence of an anion-dependent electrochemical response with F~- ion. This response was particularly dramatic in the case of receptor after the addition of ~1 equiv. of F~- ion.