A highly selective fluorescent sensor based on calix[4]arene appended benzothiazole units for Cu2+, S2- and HSO4- ions in aqueous solution

A novel calix[4]arene receptor containing benzothiazole units in 1,3-alternate conformation (L) was synthesized and characterized by H-1, C-13, APT, COSY NMR, FTIR, elemental analysis, and UV-vis spectral data. The cation and anion binding properties of L were investigated in the presence of various cations and anions. L showed "on-off' type fluorescence response towards Cu2+ with high selectivity in aqueous solution (CH3CN/H2O, 4/1, v/v). Once binding with Cu2+, L-Cu2+ complex displayed high selectivity for sulfide. Among the various anions, only sulfide anion induced the revival of fluorescence of L, resulting in "off-on" type sensing of sulfide anion. Furthermore, L served exclusive response towards HSO4- ion via hydrolysis process with 10-fold fluorescence enhancement at 542 nm. (C) 2016 Elsevier B.V. All rights reserved.