ABSTRACT A carbazole‐based fluorescent probe, CBI‐S , functionalized with a benzimidazole‐thione unit, was synthesized via Schiff base condensation for the sensitive detection of silver ions (Ag + ). Leveraging its aggregation‐induced emission (AIE) properties, the probe exhibits a robust fluorescence signal in DMF/H 2 O (3:7, v/v) medium. CBI‐S displays an instantaneous fluorescence quenching response toward Ag + with an ultrafast response time (10 s) and a remarkable detection limit of 14 nM. The probe possesses exceptional selectivity and robust anti‐interference capability in the presence of diverse coexisting metal ions, ensuring high reliability in complex environments. Furthermore, CBI‐S demonstrates a wide pH tolerance (3.0–9.0), making it suitable for various practical sensing conditions. Mechanistic investigations, validated by Job's plot and DFT calculations, revealed a 1:2 coordination stoichiometry resulting in the formation of a stable nonfluorescent complex. Finally, CBI‐S was successfully applied for Ag + determination in real water samples (tap, river, and mineral water) with satisfactory recoveries, as well as the development of portable test strips for on‐site visual monitoring. This work provides an efficient and high‐performance platform for the rapid detection of Ag + in environmental matrices.
Chen et al. (2026) studied this question.