ABSTRACT Porous organic cages are a class of adsorbents that have shown promise for a variety of applications. The octahedral cyclohexane-functionalised imine-based cage, commonly referred to as CC3, is perhaps most recognisable in this regard. However, most gas adsorption studies concerning this cage have focused on chromatographic or noble gas separations. Here, we examine this cage for the adsorptive separation of a wide variety of small molecules, including acetylene, ethylene, ethane, methane, and others. The internal surface of the cage is an optimal binding environment for gaseous substrates and as such the material displays adsorption enthalpies of −15 to −35 kJ/mol, depending on adsorbate. These values are particularly high for an adsorbent lacking coordinatively unsaturated metal sites and are likely a result of optimal cage geometry, which can be inferred from its isostructural nature to one of the pores in a well-known metal-organic framework, HKUST-1. Given this and the soluble nature of this cage, we additionally report optimisation of the high-pressure methane storage properties of this cage by tuning its density. Graphical abstract

中文翻译：

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环己烷功能化多孔有机笼中的高压甲烷储存和选择性气体吸附

摘要 多孔有机笼是一类具有广泛应用前景的吸附剂。八面体环己烷官能化亚胺基笼，通常称为 CC3，在这方面可能是最容易识别的。然而，大多数关于这种笼子的气体吸附研究都集中在色谱或惰性气体分离上。在这里，我们研究了这个笼子，用于吸附分离各种小分子，包括乙炔、乙烯、乙烷、甲烷等。笼子的内表面是气态底物的最佳结合环境，因此该材料的吸附焓为 -15 至 -35 kJ/mol，具体取决于被吸附物。对于缺乏配位不饱和金属位点的吸附剂，这些值特别高，并且可能是最佳笼几何形状的结果，这可以从其同构性质推断为众所周知的金属有机骨架 HKUST-1 中的一个孔。鉴于此以及该笼子的可溶性质，我们还报告了通过调整其密度来优化该笼子的高压甲烷储存特性。图形概要