A red fluorescent turn-on chemosensor for Al3+ based on a dimethoxy triphenylamine benzothiadiazole derivative with aggregation-induced emission

Abstract

Aluminum is a known neurotoxin to organisms and believed to cause Alzheimer's disease, osteomalacia, and breast cancer. Therefore, effective tools for Al³⁺ recognition are in great demand. In this study, a new, sensitive, and highly selective red turn-on chemosensor (TB-COOH) for Al³⁺ was prepared by combining the dimethoxy triarylamine benzothiadiazole motif and carboxyl group, where the benzothiadiazole derivative functioned as an aggregation-induced emission (AIE) moiety and the carboxyl motif functioned as the recognition site for Al³⁺. This chemosensor showed significant fluorescence enhancement upon selective addition of Al³⁺ and a relatively low detection limit (1.5 × 10⁻⁷ M). The fluorescence turn-on mechanism was ascribed to the aggregation of TB-COOH after complexation with Al³⁺, which was confirmed by ¹H NMR and FT-IR spectroscopies and scanning electronic microscopy. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al³⁺ in living HeLa cells were successfully achieved.