A new benzeneacetic acid derivative-based sensor for assessing thorium (IV) in aqueous solution based on aggregation caused quenching (ACQ) and aggregation induced emission (AIE)

Abstract

Herein a new benzeneacetic acid derivative-based luminescence sensor (2-[(2,6-dichlorophenyl)amino] benzeneacetic acid, monopotassium salt) (BA) for assessing Thorium (IV) [Th4+] in aqueous solution is introduced. In the presence of various metal ions, the BA sensor exhibits good selectivity for Th4+ ions that ranged from 0.01 µM to 0.2 µM, with a detection limit of 0.0104 µM in EtOH:H2O (v/v = 3:7) solution. The stoichiometry and the binding ability of BA ligand with Th4+ ions were studied by Job's, Hill's and modified Benesi–Hildebrand plots. The binding mode of BA ligand with Th4+ ions is 2:1. Interaction properties and the fluorescent mechanism between the BA ligand and Th4+ ions were investigated by 1HNMR, MS, FTIR and density functional theory (DFT). Furthermore, this study showed that combining the photophysical effects of aggregation caused quenching (ACQ) and aggregation induced emission (AIE) might give the benefits of reduced noise and increased signal when developing a simple luminescent sensor in aqueous environment.