A Naphthalimide-Sulfonylhydrazine Conjugate as a Fluorescent Chemodosimeter for Hypochlorite

Hypochlorite anion (ClO-) is a widely-used disinfectant and a microbicidal agent in the immune system. Accurate detection of ClO- in environmental and biological samples by simply prepared chemosensors/chemodosimeters is important. Herein, we report that a naphthalimide-sulfonylhydrazine conjugate with an imine (C=N) linker, prepared via simple condensation, acts as an effective fluorescent chemodosimeter for ClO-. The molecule exhibits a weak emission, but ClO--selective cleavage of its C=N bond creates a strong green emission. Ab initio calculation showed that the emission enhancement by ClO- originates from the suppression of intramolecular electron transfer from the photoexcited naphthalimide through the C=N linker. This response enables selective and sensitive detection of ClO- at physiological pH range (7-9) and allows fluorometric ClO- imaging in the presence of cells.