Visible light excitable 3-formylBODIPYs for selective fluorescent and colorimetric sensing of cysteine

Selective fluorescent and colorimetric sensing of cysteine in methanol-HEPES buffer (45 mM, pH [Formula: see text] 7.2, v/v [Formula: see text] 1/1) solution over various common amino acids and related thiol containing compounds has been achieved based on the cyclization reaction between the formyl group on 3-formylBODIPYs and cysteine/homocystein. Upon addition of cysteine/homocystein, 3-formylBODIPYs exhibited greatly enhanced fluorescence intensity as well as an abvious red-shift of the absorption peak (20–30 nm). The detection limits for cysteine were in the range of 1.18–2.73 [Formula: see text]10[Formula: see text] M. The detection mechanism was studied by nuclear magnetic resonance and theoretical calculation.