A naphthol-based highly selective fluorescence turn-on and reversible sensor for Al(III) ion

A naphthol derivative (E)-1-((2-(benzo[d]thiazol-2-yl)hydrazono)methyl)naphthalen-2-ol (NABT) exhibits an off-on-type fluorescent chemosensing for the detection of Al3+ ions, due to chelation-enhanced fluorescence (CHEF). The fluorescence intensity at 515 nm (excitation at 420 nm) of NABT increases about 42-fold upon addition of 20 equivalent Al3+. Moreover, the binding details of NABT with Al3+ were determined by H-1 NMR and ESI-MS studies. The NABT interacts with Al3+ in a tridentate mode to form [Al(NABT)(DMSO)], [Al(NABT)Cl(DMSO)], [Al(NABT)(DMSO)(2)] and [Al(NABT)(2)] complexes. The addition of EDTA to NABT-Al3+ complex quenches the fluorescent intensity, indicating that NABT could serve as a reversible chemosensor. (C) 2018 Elsevier B.V. All rights reserved.