Spatial Pinning of Globally Inert Pores in Superhydrophobic Hydrogen-Bonded Organic Framework for Inverse Ethane/Ethylene Separation

Abstract

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 precursor design strategy to precisely modulate secondary interaction mechanisms within porous organic frameworks, offering new horizons for customized pore engineering.