Conformation-Driven Circularly Polarized Luminescence Sign Inversion in Chiral Bispyrene Based Cocrystals with...

Circularly polarized luminescence (CPL) materials hold great promise for advanced photonic applications, yet achieving dynamic control over both the luminescent dissymmetry factor (g_lum) and wavelength remains a substantial challenge. Conventional approaches to CPL inversion often require the intricate synthesis of enantiomers or depend on specific crystal orientation effects. Herein, we propose a supramolecular cocrystal engineering approach to achieve conformation-driven CPL inversion alongside multicolor emission. The resulting single-crystals (R,R)/(S,S)-CPY^M and cocrystals (R,R)/(S,S)-CPY/OFN, (R,R)/(S,S)-CPY/TPF, (R,R)/(S,S)-CPY/TCNB exhibited tunable emission ranging from 441 nm to 591 nm, arising from arene-perfluoroarene and charge-transfer interactions. Crucially, single-crystal X-ray diffraction revealed that OFN and TCNB guests insert between the pyrene rings of the host (R,R)-CPY, enforcing an "open" conformation and yielding negative CPL signals. By contrast, TFP does not insert, preserving the "closed" conformation and producing in positive CPL of (R,R)-CPY/TFP. Furthermore, a reversible vapor-induced crystal-to-polymorphism transformation was demonstrated, enabling switchable CPL. All microcrystals functioned as low-loss optical waveguides from 0.0189 to 0.0471 dB µm^-1, underscoring their potential for integrated photonic circuits. This work provides a robust strategy for designing multifunctional chiroptical materials with controllable CPL signs through conformation regulation in cocrystal system for applications in photonics and sensing.