Chiral Reticular Self-Assembly of Achiral AIEgen into Optically Pure Metal-Organic Frameworks (MOFs) with Dual Mechano-Switchable Circularly Polarized Luminescence.

Circularly polarized luminescence (CPL) is attractive in understanding the excited-state chirality and developing advanced materials. Herein, we propose a chiral reticular self-assembly strategy to unite achiral AIEgens, chirality donors, and metal ions to fabricate optically pure AIEgen metal-organic frameworks (MOFs) as efficient CPL materials. We have found that CPL activity of the single-crystal AIEgen MOF was generated by the framework-enabled strong emission from AIEgens and through-space chirality transfer from chirality donors to achiral AIEgens via metal-ion bridges. For the first time, a dual mechano-switched blue and red-shifted CPL activity was achieved via ultrasonication and grinding, which enabled the rotation or stacking change of AIEgen rotors with the intact homochiral framework. This work provided not only an insightful view of the aggregation induced emission (AIE) mechanism, but also an efficient and versatile strategy for the preparation of stimuli-responsive CPL materials.