1,7‐Dithienyl and 3,5‐Di‐tert‐Butyl Substituted aza‐BODIPY with the Large Stokes Shift

To break through the limited structure of aryl substituted aza‐BODIPY at 3,5‐positions, we herein, prepared the novel aza‐BODIPY with the –tBu groups in 3,5‐positions ( tBu‐azaBDP ). tBu‐azaBDP possesses excellent optical properties, especially having the large Stokes shift. The –tBu substitution promotes the nonradiative transition process and has potential to enhance photothermal conversion. Due to the advantage of large Stokes shift to avoid spectral overlap and reduce the background interference, S‐tBu‐azaBDP as a fluorescent probe was found to be highly selective and sensitive to Hg 2+ .