Study by fluorescence of calix[4]arenes bearing heterocycles with anions: highly selective detection of iodide

Abstract

The present work describes a study of complexation efficiency of calix[4]arenes bearing benzoimidazolyl, benzothiazolyl, and benzoxazolyl heterocycles (5–7) towards several anions. The binding ability of calixarene derivatives 5–7 towards selected anions of different molecular geometries such as: F−, HSO4−, I−, N3−, NO3−, NO2−, SCN−, ClO4−, Br−, CN−, Cl−, CH3COO− CF3SO3− in methanol, has been investigated by fluorescence spectroscopic techniques, all anions were used as tetrabutylammonium salts to avoid possible complexation of cationic species by the derivative calix[4]arenes. Fluorescent chemosensor ability of these three calixarene derivatives was highly selective for iodide in contrast with other anions studied. The best chemosensor found, corresponds to compound 7, with an association constant of 2.01 × 104 mol−1 L and a detection limits of 0.22 ppm for iodide.