Multiresponsive and Tunable Circularly Polarized Luminescence in Aggregation-Induced Emission Static Helical Supramolecular Polyisocyanides

The realization of stimuli-responsive dynamic CPL in static helical polymers remains highly challenging. Herein, a novel, covalent, and green synthetic strategy is developed to construct AIE-featured static helical supramolecular polyisocyanides with multiresponsive and tunable CPL properties, via helix-sense-selective cationic copolymerization of AIE chiral D/L-menthyl-ester-appended aryl isocyanides and achiral stimuli-responsive azobenzene-appended aryl isocyanide by a new cationic initiator (PhEt)⁺[(Cl)B(C₆F₅)₃]^-. Notably, the CPL signal intensities of these static helical supramolecular polyisocyanides in the liquid state exhibit distinct stimulus-responsive behaviors: enhanced CPL response under humidity, an "off" CPL response in the presence of Fe³⁺ ions, and reversible "on-off" CPL switching upon light and pH stimulation. Molecular simulation methods demonstrate that stimulus-responsive regulation of the <i>cis-trans</i> isomerization of flexible azobenzene side groups lowers the energy barrier for helical conformational transformation, thereby enabling reversible conformational transitions between the helical and disordered states of the main chain and further achieving modulation of chiroptical activity. Different from static/dynamic helical polymers, azobenzene-appended helical polyisocyanides combining static and dynamic features confer enhanced stability, accuracy, and repeatability, suitable for high-performance applications in multicolor dynamic displays, anticounterfeiting, information encryption, and chiral logic gates. This work provides fundamental insights into the covalent construction of static helical polymers with stimuli-responsive dynamic CPL.