Breaking Classic Heavy-Atom Effect to Achieve Heavy-Atom-Induced Dramatic Emission Enhancement of Silole-Based AIEgens with Through-Bond and Through-Space Conjugation

Classic heavy-atom effect is well known on traditional luminophores, but its usability for newly developed AIEgens with through-bond and through-space conjugation leaves a question open. Herein, an interesting heavy-atom-induced emission enhancement against classic heavy-atom effect is reported by examining unique photophysical behaviors of aggregation-induced emission (AIE)-active silole compounds both experimentally and theoretically. It is revealed that heavy atoms exert an insignificant impact on the fluorescence of AIEgens due to their through-space conjugation nature, and weak intermolecular interactions and heavy-atom-caused vibration restriction collaboratively contribute to the emission enhancement of these AIEgens via restricting intramolecular motions. The breaking of classic heavy-atom effect on silole-based AIEgens not only proves its usability scope only on through-bond conjugated dyes, it also provides an effective and simple strategy to dramatically improve the emission efficiency of AIEgens.