A deep-red lysosome-targetable fluorescent probe for detection of hypochlorous acid in pure water and its imaging application in living cells and zebrafish.

[Display omitted] • A deep-red morpholine-functionalized fluorescent probe has been developed. • The crystal structure of the probe is reported. • The probe could monitor ClO− with low detection line (12 nM) in neat aqueous solution. • The probe work with wide pH rang of 1.0–12.0, and the process of quench completed within 10 s. • The probe has been successfully applied to the imaging of ClO− in the lysosomes of living cells and zebrafish. Hypochlorite plays a significant role in physiological processes, particularly regulation of lysosomal functions, and is involved in various diseases. Thus, it is crucial to develop highly sensitive and selective molecule tools to detect HClO in lysosomes. Herein, a novel 2 H -benzo[ h ]chromene-pyridine derivative (1) was synthesized through condensation reaction, which exhibited a notable deep-red emission at 640 nm in pure water. This deep-red emission was specifically quenched by adding ClO−. The response of probe 1 toward ClO− was rapid (within 10 s), sensitive (detection limit of 0.012 μM), and effective over a wide range of pH (1.0–12.0). Due to the existence of morpholine as the lysosome-targeting unit, the probe was successfully utilized to monitor lysosomal ClO−. Moreover, the probe 1 was also applied to detecting ClO− in zebrafish. [ABSTRACT FROM AUTHOR]