A colorimetric and ratiometric fluorescent probe for sulfite based on an intramolecular cleavage mechanism

A colorimetric and ratiometric fluorescent sulfite probe, the levulinate of 4-hydroxynaphthalimide, was successfully synthesized from 4-hydroxy-naphthalimide and levulinic acid. Through sulfite-mediated intramolecular cleavage, the probe was converted into 4-hydroxynaphthalimide, which when excited at 450 nm, displayed a large Stokes shift due to the intramolecular charge transfer process. The probe exhibited high selectivity and sensitivity towards sulfite over other typical anionic species (F-, Cl-, Br-, I-, HPO42-, SO42 -, NO3-, AcO-, ClO4-, HCO3-) in HEPES-buffered solution (25 mM, pH 7.4, 50% acetonitrile, v/v). Copyright (C) 2013 John Wiley & Sons, Ltd.