A far-red ratiometric fluorescent probe for SO2 derivatives based on the ESIPT enhanced FRET platform with improved performance

A ratiometric fluorescent probe (L-HF3) based on an efficient FRET platform constructed by 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) and 3-hydroxyflavone (HF) fluorophores for detection of sulfur dioxide derivatives (HSO 3 − /SO 3 2− ) was developed. The probe featured very large (pseudo) Stokes shifts , good selectivity and high sensitivity, high FRET efficiency and high resolution of the emission bands. The probe was also mitochondria-targeted and could detect exogenous and endogenous bisulfite in living cells.