A Sensitive and Reusable Phenothiazine-Benzophenone Based Fluorescence Probe for Detecting Hypochlorite in Environmental and Biological Systems.

This study addresses the critical issue of irreversible oxidation in hypochlorite (ClO⁻) sensing by a phenothiazine-based compound, which typically leads to the probe's degradation and loss of functionality. We introduce a novel fluorescence probe, (2-(5-(10 H-phenothiazin-10-yl)thiophen-2-yl)-1 H-benzo[d]imidazol-6-yl)(phenyl)methanone (PTH-BP), specifically designed to enhance ClO⁻ detection efficiency. PTH-BP exhibits strong aggregation-induced emission (AIE), emitting deep orange fluorescence at 620 nm with a large Stokes shift of 195 nm, and achieves an impressive detection limit of 1 nM in ACN/PBS buffer solutions. Job's plot analysis reveals a 1:1 binding stoichiometry, while fluorescence quenching occurs due to the oxidation of the phenothiazine sulfur to sulfoxide, confirmed by high-resolution mass spectrometry (HRMS). The probe's design improves stability, enabling effective real-time ClO⁻ monitoring and demonstrating reliable performance in electrochemical sensing. Furthermore, PTH-BP shows excellent imaging capabilities in HeLa cells, characterized by low toxicity and good permeability, making it a strong candidate for environmental, biological, and industrial applications. This breakthrough offers a robust and versatile approach to overcoming limitations in phenothiazine-based ClO⁻ sensing.