Adaptive Co-Crystals with Switchable Host-Guest Stoichiometry for Dynamic Regulation of Photoluminescence.

The development of photoluminescence materials with tunable properties through structural and functional modifications remains a fascinating yet challenging task. In this work, the concept of adaptive co-crystals featuring switchable host-guest stoichiometry within the realm of pillararene-based supramolecular chemistry is proposed. This strategy allows for the rational design of a diverse range of through-space charge-transfer co-crystals, enabling dynamic modulation of photoluminescence in the solid state. Experimental and theoretical findings unveil two distinct phases within each set of co-crystal architectures, characterized by different donor/acceptor stoichiometric ratios as well as molecular packing modes. Notably, these co-crystalline phases undergo vapor-induced stoichiometry switching and structural interconversion, resulting in unique charge-transfer transition states and enabling reversible control over photoluminescent behavior. Particularly, this dynamic modulation of the cavity apertures, driven by stoichiometric variation, facilitates highly selective capture and release of 1-bromoalkane under mild conditions. The present study highlights the potential application of vapor-mediated co-crystals with switchable stoichiometry as a supramolecular strategy for modulating the intrinsic characteristics of intermolecular donor-acceptor materials.