A simple dihydrophenazine-based chemosensor for the detection of sulfite with turn-on fluorescence

A simple novel dihydrophenazine-based chemosensor R has been developed for the detection of SO32- in DMSO-H2O solution with turn-on fluorescence. Upon the addition of sulfite, the ICT (intramolecular charge transfer) system of the probe was destroyed owing to the nucleophilic addition of sulfite to the formyl group of R. Thus a charming orange-red fluorescence centered at 603 nm appeared, which is favorable for potential biosensing. The reaction mechanism was confirmed by MS and H-1 NMR titration. In addition, the detection limit for sulfite was determined as low as 71.4 nM, which is superior to many reported probes. All above results promote the probe as a promising candidate in practical and biological applications.