α‐Acrylaldehyde 3‐Pyrrolyl BODIPY as a Specific Optical Sensor for Cysteine and Homocysteine

Abstract A new fluorophore, α ‐acrylaldehyde 3‐pyrrolyl BODIPY was synthesized by treating 3‐pyrrolyl BODIPY with a mixture of 3‐(dimethylamino) acrolein and POCl 3 under Vilsmeier–Haack reaction conditions. The X‐ray structure revealed that the fluorophore was almost planar, and the appended pyrrole was in the same plane with a small deviation from the mean plane. We investigated the potential use of α ‐acrylaldehyde 3‐pyrrolyl BODIPY for sensing thiol containing amino acids such as cysteine/homocysteine (Cys/Hcy). Our studies showed that the α ‐acrylaldehyde‐ 3‐pyrrolyl BODIPY was found to be useful for exclusive sensing of Cys/Hcy and to exhibit different optical signaling responses to Cys and Hcy at physiological pH in aq. CH 3 CN (1 : 1 v/v, PBS) medium. The enhancement in optical properties for Cys and quenching in same properties for Hcy was attributed to different binding modes of Cys/Hcy with α ‐acrylaldehyde 3‐pyrrolyl BODIPY.