Airflow-Driven Programmable Chirality Control: From Sub-1 nm GdOOH Nanowires to Reversible Macroscopic Helical Assemblies

We report the controlled synthesis of fully programmable macroscopic chirality in hierarchical inorganic assemblies through the introduction of directional spiral airflow during evaporation-induced self-assembly of sub-1 nm gadolinium oxyhydroxide (GdOOH) nanowires. Extending previous observation of spontaneous centimeter-scale macroscopic helical assemblies (MHAs) without chiral dopants and with random handedness, we demonstrated 100% deterministic control over helicity, with left- or right-handed structures formation depending on the direction of airflow. This effect is independent of gas composition, confirming a purely mechanical shear-driven mechanism. Moreover, the resulting MHAs can be readily dissolved to regenerate the homogenous nanowire dispersion, allowing repeated cycles of assembly with inverted handedness and creating true dynamic programmability in a dopant-free inorganic system. This simple yet strong approach overcomes the random nature of macroscopic inorganic chirality, revealing supramolecular-like reversibility. These findings open new pathways for engineerable chiroptical materials with potential applications in photonics, catalysis, and beyond.