Spatial pinning of globally inert pores in a superhydrophobic hydrogen-bonded organic framework for inverse ethane/ethylene separation

Overcoming the intrinsic polarity of hydrogen bonds to construct a C₂H₆-affinitive nonpolar pore environment using an entirely pore-oriented π-conjugated core presents a formidable challenge within hydrogen-bonded organic frameworks (HOFs). Herein, we propose a spatial pinning strategy for HOF pore construction. Hydrophobic molecular struts are pre-pinned within the precursor to restrict the conformational freedom of hydrogen-bonding arms, thereby governing framework stereochemistry, suppressing undesired π-π stacking, and generating four-way interconnected cavities between π-conjugated layers. Importantly, multiple interpenetrations shield polar hydrogen bonds, enabling a globally inert framework, as evidenced by an impressive contact angle exceeding 153° and an ultralow water vapor uptake of 0.057 g g^-1. Gas sorption experiments demonstrate a C₂H₆ adsorption capacity of 91.5 cm³ g^-1 and a C₂H₆/C₂H₄ selectivity of 2.0. Gas-loaded single crystals and theoretical calculations reveal that this globally inert pore environment profoundly enhances van der Waals forces between the host framework and C₂H₆, facilitating efficient gas packing. Furthermore, this HOF can produce high-purity C₂H₄ (>99.9%) from dynamic breakthrough experiments, with a maximum productivity of 36.0 L kg^-1. This work introduces a pivotal advancement in the precursor design strategy to precisely modulate secondary interaction mechanisms within porous organic frameworks, offering new horizons for customized pore engineering.