Controlling Adaptive Flexibility for Efficient Purification of Ethylene From Ethane.

Ethane-selective adsorbents enable direct production of high-purity ethylene, yet rational improvement of selectivity and productivity remains challenging. Here, we report a strategy of adaptive flexibility control. A family of isostructural metal azolate frameworks featuring bent linkers and size-tunable substituents were designed and synthesized. Single-crystal X-ray diffraction and computational simulations unveiled a bending-adsorption coupling mechanism: the stronger ethane binding drives more pronounced linker flattening to reinforce itself. Crucially, bulkier substituents reinforce this adaptive response, further elevating ethane selectivity. Notably, mixture breakthrough experiments demonstrated that navigating the selectivity-capacity trade-off via substituent-tuned adaptive flexibility afforded superior ethylene purification productivity.