Fluorogenic Thorium Sensors Based on 2,6-Pyridinedicarboxylic Acid-Substituted Tetraphenylethenes with Aggregation-Induced Emission Characteristics

A novel fluorescent sensor based on tetraphenylethene (TPE) modified with 2,6-pyridinedicarboxylic acid (PDA) that shows aggregation-induced emission (AIE) characteristics for thorium recognition with remarkable fluoresence enhancement response has been synthesized. This sensor is capable of visually distinguishing Th4+ among lanthanides, transition metals, and alkali metals under UV light. Th4+ can be detected by the naked eye at ppb levels owing to the AIE phenomenon. The sensor showed high selectivity for Th4+ compared to all other metals tested, and this recognition displayed good anti-interference qualities. This study represents the first application of a AIE fluorescence sensor in actinide metal recognition and it has potential applications in environmental systems for thorium ion detection.