Unlocking Multi‐Stimuli Synergistic Fluorescence Regulation via Strategic Ortho‐Hydroxyl Engineering of Cyanostilbene Derivatives

ABSTRACT Achieving dynamic regulation of isomerization‐induced fluorescence in cyanostilbene derivatives in response to complex environmental stimuli remains a critical challenge for their advanced applications. Herein, the strategic introduction of a single hydroxyl group at the ortho‐position of the β‐aryl ring endows α‐cyanostilbene derivatives with unprecedented multi‐stimuli‐responsive fluorescence synergistically regulated by light, solvent polarity, and metal‐ion. In low‐polarity solvents, photoirradiation triggers an extraordinarily large hypsochromic shift of up to ∼190 nm, accompanied by significant fluorescence enhancement, which is rarely achieved in α‐cyanostilbene derivatives. In sharp contrast, the photoinduced fluorescence response is almost completely suppressed in high‐polarity media owing to polarity‐promoted twisted intramolecular charge transfer (TICT). Remarkably, Al 3 + coordination suppresses TICT and lowers the Z / E isomerization barrier, thereby not only reactivating the suppressed photoresponses but even amplifying the magnitude of the blueshift and fluorescence enhancement. This represents the first example of triple‐stimuli synergistic control of Z / E isomerization fluorescence in the α‐cyanostilbene family. Experimental observations combined with theoretical calculations reveal the underlying mechanism behind the multi‐stimuli‐responsive fluorescence. Consequently, this work establishes a versatile molecular design paradigm, paving the way for the development of next‐generation intelligent photonic materials and environment‐adaptive sensing systems.