Bifunctional phenothiazine-Coumarin probe Tz.3: Visual detection of Ag+/ ClO− in aqueous media and selective imaging of hypochlorite in living cells

Excessive exposure of hypochlorite ions (ClO⁻) and silver ions (Ag⁺) lead to significant environmental safety and human health risks. How to quick and accurate detecting of Ag⁺ and ClO⁻ in aquatic environment seems urgent. Continuation of preliminary work, a novel bifunctional fluorescent probe molecule of Tz.3 was designed basing on an electron donor phenothiazine core structure with intramolecular charge transfer (ICT) effect. Experimental results showed that fluorescent probe molecule of Tz.3 can rapidly detect ClO⁻ with LOD = 2.478 nM in less 30 s and no response to Ag⁺ in MeOH/PBS solution. However, under UV lamp irradiation, Tz.3 can respond to Ag⁺ with LOD = 8.628 nM. Furthermore, the sensing mechanism of Tz.3 to ClO⁻ and Ag⁺ ions were elucidated by characterization of the reaction products with UV–vis absorption, fluorescence emission spectroscopy, mass spectrometry, and DFT calculations. Finally, the colorimetric-fluorescent dual-response fluorescent probe molecule of Tz.3 was applied to detect Ag⁺ and ClO⁻ ions in real water samples, and demonstrates significant potential for monitoring exogenous and endogenous ClO⁻ in living cells.