A highly selective fluorescent probe for Al3+ based on bis(2-hydroxy-1-naphthaldehyde) oxaloyldihydrazone with aggregation-induced emission enhancement and gel properties.

Abstract

An efficient fluorescent probe, bis(2-hydroxy-1-naphthaldehyde) oxaloyldihydrazone (1), has been prepared for the selective sensing of Al3+ over other common metal ions in water-containing media. The 1:1 stoichiometry of 1 and Al3+ was determined from Job's plot and Benesti-Hildebrand plot. The binding constant was observed as 1.6×105M-1, and the limit of detection was found to be 0.36μM, which was far below the drinking water restriction of Al3+ by EPA (the maximum allowable value is 7.4μM). In addition, the inherent AIEE features of 1 were observed upon addition of water to DMSO solution due to the restriction of the intramolecular motion, which makes the molecular conformations rigid and planar. Moreover, 1 could act as a novel gelator to form thermo-reversible supramolecular organogel with significant green emission in DMSO-H2O (v/v, 9:1) solution.