Optimizing the pore environment in biological metal–organic frameworks through the incorporation of hydrogen bond acceptors for inverse ethane/ethylene separation

Through pore engineering strategy, methyl group was successfully incorporated into two new bio-MOFs with multiple amino groups. The incorporation of abundant methyl groups significantly enhances the host–guest interaction within the confined pores, thereby enabling efficient inverse ethane/ethylene separation. • Cu-AD-DMSA exhibited a preferential adsorption of C 2 H 6 over C 2 H 4 . • The selectivity of Cu-AD-DMSA for C 2 H 6 /C 2 H 4 can reach up to 2.4. • An adsorbent has been developed for the inversion separation of C 2 H 6 /C 2 H 4 . The development of efficient adsorbents for the selective separation of ethane (C 2 H 6 ) and ethylene (C 2 H 4 ) is essential for the cost-effective production of high-purity ethylene. Here, we employ a pore engineering strategy to optimize the pore environment of biological metal–organic frameworks (MOFs) by incorporating hydrogen bond receptors to enhance the inverse separation efficiency of C 2 H 6 and C 2 H 4 . Compared to the isomorphic Cu-AD-SA, the methyl-functionalized Cu-AD-MSA and Cu-AD-DMSA not only provide suitable pore confinement but also offer additional binding sites, thus creating an optimal environment for strong interactions with C 2 H 6 (AD = adenine, SA = succinic acid, MSA = 2-methylsuccinic acid, and DMSA = 2,2-dimethylsuccinic acid). Adsorption results show that Cu-AD-DMSA exhibits remarkable C 2 H 6 /C 2 H 4 selectivity (up to 2.4) as well as outstanding C 2 H 6 adsorption capacity (3.63 mmol g −1 ), surpassing most reported C 2 H 6 -selective MOFs. Theoretical calculations combined with in situ infrared spectroscopy reveal that the synergetic effect of suitable pore confinement, amino groups, and functional surfaces decorated with multiple methyl binding sites provides strong and multipoint interactions for C 2 H 6 . Breakthrough experiments demonstrate that Cu-AD-DMSA exhibits exceptional performance in separating binary C 2 H 6 /C 2 H 4 gas mixtures. The high chemical and thermal stability, scalable synthesis, and economic viability of Cu-AD-DMSA illustrate its potential as a candidate for C 2 H 6 /C 2 H 4 separation application.