Reversible Transformation between 0D Cluster and 1D Chain with Luminescence and Dielectric Dual Switching in Two New Decanuclear Copper(I) Iodide Halides.

Low-dimensional emissive Cu(I) halides have garnered extensive attention owing to their structural diversity and unique, structure-dependent photophysical properties. Nevertheless, achieving structural transitions with switchable physical properties remains a formidable challenge for high-nuclearity Cu(I) halides, and reported zero-dimensional (0D) to one-dimensional (1D) structural dimensionality transformations are extremely scarce. Herein, two decanuclear Cu(I) iodide halides, namely [Pr2-DABCO]5[Me2NH2]Cu10I20I·(MeCN)2 (1) and [Pr2-DABCO]3[Me2NH2]Cu10I17 (2) ([Pr2-DABCO]2+ = N,N'-dipropyl-1,4-diazabicyclo-[2.2.2]octan-1-ium cation; [Me2NH2]+ = dimethylamine cation; MeCN = acetonitrile) are synthesized. Compound 1 features isolated [Cu10I20]10- clusters, while 2 exhibits infinite 1D [Cu10I17]n7n- chains, and both represent rare structural prototypes among the reported Cu(I) iodide clusters. Remarkably, a reversible structural transformation between 1 and 2 is achieved, accompanied by a high-contrast emission color change from a weakly orange-emissive 0D phase to a bright green-emissive 1D structure. Compound 2 exhibits a 3-fold enhancement in the photoluminescence quantum yield (PLQY), reaching a maximum value of 74.59%. Impressively, 2 also enables high-contrast, stable, and reversible dielectric "silent → active" switching owing to the order-disorder transition of organic [Me2NH2]+ cations. This work reports two decanuclear Cu(I) halides, capable of reversible 0D/1D structural interconversion, which enables dual optical and dielectric bistable switching, providing a new platform for the design and fabrication of multifunctional responsive materials.