Ultrasound‐induced circularly polarized luminescence based on homochiral aggregation of clothespin‐shaped Pt(II) complexes

Ultrasound‐induced circularly polarized luminescence (CPL) was achieved using planar chiral, binuclear clothespin‐shaped trans‐bis(salicylaldiminato)platinum(II) complexes. Solutions of the clothespin‐shaped platinum(II) complexes anti‐1a–c in cyclohexane immediately transformed into stable gels upon brief ultrasound irradiation. The ultrasound gels exhibited intense phosphorescent emissions at room temperature, whereas none of the solution exhibited significant emissions under UV light illumination. Interestingly, gels prepared from optically pure complexes exhibited CPL activity at room temperature with an anisotropy factor of |glum| = 1.5–2.6 × 10−3. The emissive gels were readily converted to the original non‐emissive solution upon heating and cooling to room temperature and could be gelled again by ultrasound irradiation. In addition, chromogenic control from green to red emission can be achieved simply by introducing MeO groups at different positions on the aromatic rings. Ultrasound‐induced circularly polarized luminescence (CPL) has been achieved using clothespin‐shaped Pt complexes. The non‐emissive sol was instantly converted to a CPL‐active gel using an ultrasound stimulus. It can recover to its original sol state by heating, enabling reversible CPL switching. Furthermore, we succeeded in controlling the luminescence color in the gel state by introducing substituents at the appropriate positions.