Stimulus-Induced Microflexible Nanopores in Zinc-Based Coordination Network Enable Four Distinct Adsorption Mechanisms for Efficient Light Hydrocarbon Separations

Understanding adsorption mechanisms is fundamental to advancing gas separation science and technology. Nevertheless, sorbents that undergo stimulus-induced fine-tuning of their structures to enable multiple adsorption mechanisms are rarely reported. Here, we report that CALF-20, a zinc-based coordination network, exhibits temperature and guest-induced microflexibility to exhibit four distinct and tunable adsorption mechanisms for nine light hydrocarbon gases: (i) thermodynamic selectivity (ethane/ethylene separation); (ii) kinetic-limited adsorption (propane, n-butane, and n-butene); (iii) molecular sieving (iso-butane/iso-butene); (iv) gate-opening flexibility (butadiene capture in the presence of n-alkane impurities). In effect, temperature-dependent structural flexibility enables modulation of guest diffusion kinetics and adsorption thermodynamics. CALF-20 thereby achieves propylene purification from propane and butadiene purification with exceptional selectivity. Structural and computational insights into the mechanisms governing the selective separation of light hydrocarbons using CALF-20 reveal the potential of targeted flexible nanoporous materials with dynamically tunable pore environments, paving the way for next-generation separation technologies in the petrochemical and energy sectors.