Dual‐Stimuli‐Responsive Turn‐On Luminescence of Chiral Bisimidazolyl BINOL Dimethyl Ether Crystals

Abstract Stimuli‐responsive organic luminescent crystals have attracted significant attention in recent years for their potential in sensor and memory applications. While turn‐on luminescence is superior in detection sensitivity compared with turn‐off luminescence, the development of organic crystals that exhibit turn‐on luminescence in response to multiple stimuli remains a significant challenge. Herein, the crystals of chiral bisimidazolyl 1,1′‐bi‐2‐naphthol (BINOL) dimethyl ether have exhibited a dual‐stimuli‐responsive turn‐on luminescence based on two distinct mechanisms. In the crystalline state, luminescence was substantially quenched by the intermolecular hydrogen bonds between the imidazole rings. Mechanical stimulation induced a transition to a blue‐violet‐emissive amorphous state. In contrast, thermal stimulation produced an orange luminescence, attributed to excited‐state intramolecular proton transfer (ESIPT) luminescence from thermally demethylated products. Furthermore, the thermally induced state exhibited circularly polarized luminescence (CPL), marking a rare instance of stimuli‐responsive turn‐on CPL in a solid‐state system. This study provides new insights into environmental and structural factors for solid‐state luminescent properties and advances the design guidelines for multifunctional luminescent sensors.