"Turn-on" fluorescence sensor for Sc3+ based on Schiff-based tetraphenylethylene.

"Turn-on" fluorescent sensors have garnered significant attention for their high signal-to-noise ratio. However, the development of aggregation-induced emission (AIE) probes for Sc3+ detection remains limited, with only a few examples reported to date. In this work, we rationally designed and synthesized a novel tetraphenylethylene (TPE) derivative functionalized with Schiff-base-bridged isophthalhydrazide, achieving a satisfactory yield of 85%. The probe exhibits prominent AIE characteristics and demonstrates exceptional selectivity toward Sc3+ over a wide range of competing metal ions, including representative lanthanides, in THF/H2O (5 : 95, v/v) mixed medium, accompanied by a significant fluorescence "turn-on" response upon Sc3+ binding. The detection limit was determined to be 3.57 × 10-8 M. A comprehensive mechanistic investigation, including fluorescence titration, FT-IR, 1H NMR, and mass spectrometry, unequivocally established a 1 : 1 binding stoichiometry between the probe and Sc3+. Furthermore, the practical applicability of this sensor was successfully validated through test strip experiments and simulated water sample analyses, highlighting its potential for environmental monitoring and Sc3+ detection in aqueous-organic mixed media.