A ratiometric fluorescent probe for SO2 derivatives based on a new coumarin-hemicyanine dye in living cells.

[Display omitted] • A new dye was synthesized and the spectral properties were studied. • The dye showed good spectral properties and was used to detect SO 2 derivatives. • The reactivity of the probe could be regulated by the thiomorpholine group. A new coumarin-hemicyanine dye was synthesized and used as a ratiometric fluorescent probe for SO 2 derivatives (HSO 3 -/SO 3 2-). The probe showed deep-red fluorescence, ratiometric response, good selectivity, low detection limit and well-separated emission bands. Moreover, the probe was mitochondria-targeted, and was applied to image SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]