Study by fluorescence of calix[4]arenes bearing heterocycles with divalent metals: highly selective detection of Pb2+

Abstract

The present work describes a study of complexation efficiency and selectivity of calix[4]arenes bearing benzoimidazolyl, benzothiazolyl, and benzoxazolyl heterocycles (5–7) towards several selected metal ions using fluorescence and UV–Vis spectroscopy. The binding ability of calixarene derivatives 5–7 toward selected divalent metal ions such as Ca, Cd, Pb, Ni, Mg, Mn, Co, Fe and Zn has been investigated by fluorescence spectroscopic techniques. Fluorescent chemosensor ability of three calixarene derivatives was highly selective for Pb (II) in contrast with other divalent metal studied. The highest association constant corresponds to benzoxazolyl calixarene derivative 7, with a Ka of (1.37 ± 0.06) 9 104 mol-1 L and detection limit for lead of 1.14 ± 0.05 mg L-1 in methanol being acceptable for the recognition of this metal at micromolar concentrations.