1,7‐Di‐tert‐butyl‐Substituted aza‐BODIPYs by Low‐Barrier Rotation to Enhance a Photothermal‐Photodynamic Effect

Abstract 1,7‐Di‐ tert ‐butyl‐substituted aza‐BODIPYs ( tBu‐azaBDP ) were successfully obtained for the first time. The structures of tBu‐azaBDP and Ph‐azaBDP were confirmed by X‐ray crystal analysis, and tBu‐azaBDP 2 is more twisted than Ph‐azaBDP 5. tBu‐azaBDP s have significant photo‐stability and enhanced water solubility. tBu‐azaBDP s possess excellent optical properties, such as high molar extinction coefficients, broad full width half maxima, and large Stokes shifts, which is comparable to those of the parent dye Ph‐azaBDP . Although the low‐barrier rotation of the distal ‐tBu groups in tBu‐azaBDP s results in low quantum yield, photothermal conversion efficiency and singlet oxygen generation ability of tBu‐azaBDP s are more effective than those of Ph‐azaBDP , which is highly desirable for a photothermal‐photodynamic therapy agent.