Achiral guest-mediated modulation of circularly polarized luminescence in chiral charge-transfer cocrystals

Chiral charge-transfer (CT) systems provide an important platform for the development of circularly polarized luminescence (CPL) materials. However, precise modulation of CPL performance remains challenging. Herein, we report a host–guest supramolecular assembly strategy based on a naphthalene diimide-derived triangular macrocycle to construct a series of chiral CT single-crystal systems. A variety of aromatic guest molecules co-assemble with the host macrocycle through π–π stacking interactions, forming highly ordered supramolecular architectures. Although the parent macrocycle exhibits pronounced circular dichroism (CD) signals, it is CPL-inactive. Remarkably, upon co-assembly with achiral guest molecules, strong CPL responses emerge, indicating efficient transfer of ground-state chirality into the excited state. Notably, the CPL intensity varies significantly among the single-crystal systems, with |g_lum| values reaching up to 0.011. In addition, the emission color can be tuned from yellow to orange and red, enabling guest-dependent regulation of photophysical properties. Mechanistic studies reveal that multiple noncovalent interactions, particularly host–guest π–π stacking, cooperatively facilitate CT processes, thereby enabling effective modulation of excited-state chirality and CPL properties. This work provides a robust supramolecular strategy for constructing tunable chiral luminescent single-crystal materials.