A water-soluble colorimetric and ratiometric fluorescent probe based on phenothiazine for the detection of hypochlorite ion

A new water-soluble colorimetric and ratiometric fluorescent probe for detecting hypochlorite ion (ClO−) based on a phenothiazzine group was designed and synthesized. As ratiometric fluorescent probe, LD-Lyso showed rapid, accuracy, and selective fluorescence sensing effect for ClO− in PBS buffer solution with a large Stokes shift (195 nm), it displayed a significant blue-shift phenomenon and a 25-fold enhancement of the fluorescence intensity ratio (I550/I635) toward ClO−, fluorescence notably changing from red to green, the detection limit as low as 8.74 μM; As colorimetric probe, LD-Lyso also showed a significant shift in absorption band (from 450 to 395 nm) upon treatment with ClO− along with the visible color changed from faint yellow to colorless, the detection limit as low as 0.01 μM. In addition, the detecting mechanism of LD-Lyso towards ClO− via the intramolecular charge transfer (ICT) mechanism was proved by ESI-MS and DFT calculation, and the application as testing strips for detecting ClO− was realized.