Cyclooctatetraenyl Metal-Organic Octahedra and Their 3D Cage to 2D Nanosheet Transformations

In biological systems, certain fundamental biomacromolecules, such as proteins and DNA, fulfill specific biological functions via structural changes triggered by stimuli. Herein, we report the synthesis of two allosteric regulation metal-organic octahedra (S1 and S2) with tailored cavities/windows. Both cages exhibit distinct aggregation-induced emission (AIE) colors and quantum yields. Single-crystal x-ray diffraction reveals that S2, featuring longer arms, adopts a denser π-stacking arrangement, rationalizing its superior emissive properties. The kinetically driven multicomponent heteroleptic octahedral mixtures formed under ambient temperature assembly conditions transformed into self-sorted S1 and S2 upon heating. The addition of competitive building blocks enabled the transformation from S1 to S2. Notably, 365 nm light irradiation induces planarization of the COT units, driving a rapid structural transformation from three-dimensional (3D) octahedra to two-dimensional (2D) metal-organic nanosheets (NS-1 and NS-2) within minutes. This work provides a novel approach for designing responsive systems and demonstrates broad potential applications in areas such as optoelectronics, targeted delivery, and smart materials.