A Two-Way Rod-Packing Indium-Based Nanoporous Metal–Organic Framework for Effective C₂/C₁ and C₂/CO₂ Separation

The exploration of reticular chemistry pertaining to rod-packing metal–organic frameworks and the development of solid adsorbents for multitask hydrocarbon separations are two active topics of current research. In this study, an In-organic coordination framework compound denoted ZJNU-121 was assembled from a custom-designed bithiophene-functionalized tetracarboxylate ligand. The title compound not only exhibited a rare two-way rod-packing pattern but also displayed the impressive capability of capturing C2 hydrocarbons from CH4 and CO2 to achieve C2/C1 and C2/CO2 separations. Under ambient conditions, the ideal adsorbed solution theory-predicted adsorption selectivities for equimolar mixtures fall in the range of 8.4–13.8 (C2Hn/CH4) and 2.3–3.4 (C2Hn/CO2). Such separation potentials were also ascertained by the column breakthrough experiments. Furthermore, the in-depth theoretical insight unveiled the crucial role of active sites such as thiophene sulfur, carboxylate oxygen, and the bridging μ2-OH group in capturing C2 hydrocarbons in preference to CO2 and CH4. Additionally, the structural integrity of ZJNU-121 can be retained in aqueous solutions with pH values varying from 3 to 11 for 24 h at ambient temperature, as verified by the preservation of PXRD patterns, textural characteristics, and static/dynamic adsorption behaviors. This research not only enriched the architectural diversity of rod MOFs but also reported a robust adsorbent with good application prospects for diversified hydrocarbon separations.