Customized Flexibility in Soft Porous Crystals With Coupled Dynamics for Matching Separation of Light Hydrocarbons

Soft porous crystals exploit adaptive structural dynamics for molecular recognition, yet their elusive nature hinders the fundamental understanding of rational design and reliable applications. Here, the correlation dynamics intrinsic to layered M(pbe)-α (M = Co²⁺, Zn²⁺, Cu²⁺), transmitting from mono-vertex to strained-linker and to self-adaptive grid/stack, are orchestrated into node-encoded flexibility. In-situ tracking of dynamic structural evolution (including vertex distortion, linker rotation, layer motion, and pore resculpting) reveals the cation-induced flexibility gradient Co > Zn > Cu, evidenced by changes in coordination bond lengths, unit cell volumes, and inter/intra-layer interactions. The activated phase Co(pbe)-β exhibits strong flexibility, undergoing a polarizability-driven response for acetylene, achieving a record acetylene/carbon dioxide uptake ratio of 75. Zn(pbe)-β with moderate flexibility displays a marked difference in response to propylene versus propane. Cu(pbe)-β with the weakest flexibility shows high selectivity for dispersion-driven adsorption of butadiene over n-butene. Breakthrough experiments confirm exceptional separation and cyclic performance, where efficient desorption yields high-purity (≥ 99.5%) acetylene, propylene, and butadiene. Thus, correlating the local dynamic extent of coordination bonds with weak interaction constraints, as well as global cell volume expansion extent in these finely fabricated layered soft crystals, enables customized flexibility for the matched separation of challenging C2-C4 mixtures.