Cyclodextrin‐Directed Assembly of Dynamic Polyoxometalate Pseudo‐Rotaxanes

ABSTRACT Cyclodextrins (CDs) are widely used as host molecules in supramolecular chemistry, yet their capacity to actively direct structural reorganization of inorganic clusters remains largely unexplored. Here, we demonstrate that α ‐CD can direct inorganic cluster reorganization during self‐assembly, enabling the synthesis of previously inaccessible azobenzene‐functionalized polyoxometalate (POM) pseudo‐rotaxanes, in which the macrocycle not only encapsulates the organic axle but also governs the structural evolution of the inorganic core. Upon complexation with α ‐CD, a flat arsonate‐functionalized {Mo 6 } cluster reorganizes into a bent analogue, yielding a dynamic pseudo ‐rotaxane assembly ( 1a @ α ‐CD). Fine pH modulation subsequently induces a CD‐mediated transformation into an inverted‐Keggin {Mo 12 } pseudo ‐rotaxane threaded by four α ‐CD units. NMR/ITC titration, DOSY/NOESY analyses, and single‐crystal x‐ray diffraction collectively reveal dual threading pathways and delineate the dynamic {Mo 6 } to {Mo 12 } reorganization process. Crucially, α ‐CD suppresses precipitation of hydrophobic ligands under strongly acidic conditions and stabilizes transient coordination states, thereby enabling cluster growth pathways inaccessible under identical synthetic conditions in the absence of α ‐CD. These findings demonstrate that CDs can actively direct inorganic self‐assembly through host‐guest interactions, providing a supramolecular route to previously inaccessible POM pseudo ‐rotaxanes and opening new opportunities for adaptive hybrid architectures.