Electronic-Structure-Directed Pore Engineering in Metal-Organic Frameworks for Molecular Sieving of C₃F₆/C₃F₈

Trace removal of hexafluoropropylene (C₃F₆) from octafluoropropane (C₃F₈) is crucial for producing high-purity fluorinated electronic gases, yet it remains highly challenging because of their similar molecular dimensions. Here, we report an electronically driven pore-engineering strategy for C₃F₆/C₃F₈ separation, in which Jahn-Teller-active Cu²⁺ directs framework reconstruction from the large-aperture channels of ZnTPO (H₃TPO = tris(4-carboxyphenyl) phosphine oxide) to the narrow cage-like pore network of CuHTPO, thereby switching the separation behavior from co-adsorption to molecular sieving. Consequently, CuHTPO delivers > 99.999% pure C₃F₈ with productivities of 314.9 and 2819 L kg^-1 from 1/9 and 1/99 C₃F₆/C₃F₈ mixtures, respectively. Optical imaging at the single-particle level directly visualizes the rapid transport of C₃F₆ through the channels, while single-crystal X-ray diffraction, FTIR spectroscopy, and molecular simulations collectively elucidate the structural origin of the electronically regulated sieving behavior. Taken together, this work positions electronic-structure-directed pore reconstruction as a powerful material-design strategy for programming confined pore spaces, enabling robust and recyclable molecular sieving of closely related gases.