Synthesis of calix[6]arene and transduction of its furfural derivative as sensor for Hg(II) ions

Abstract

The new approach has been developed for the synthesis of p-tert-butylcalix[6]arene using toluene as a solvent. The synthesized p-tert-butylcalix[6]arene has been functionalized with 5-methylfurfural (PTC6AF) as a specific receptor for the Hg(II) metal ion. This study investigated the impact of the selective mercury receptor and sensor. It is observed that modifications of the nature of the wide rim substituent alter the efficiency of sensation toward metal cations. Hence, this makes the synthesized receptor PTC6AF very selective toward the Hg(II) metal ion among K(I), Be(II), Mg(II), Ca(II), Sr(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), Sb(III), Eu(III), Gd(III), Th(IV), W(VI) and U(VI) ions used as their chlorides. This type of functionalization of the p-tert-butylcalix[6]arene by furfural led to a receptor with a wide scope when investigated by UV–visible and fluorescence spectroscopy for selective binding of Hg(II). The binding properties of the receptor and Hg(II) were further studied using cyclic voltammetry and mass spectrometry. The receptor-Hg(II) stoichiometry and association affinity are established by a Benesi-Hildebrand plot and the method of continuous variation (Job’s plot) with an association affinity K = 3.382 × 106 M−1.