Pyrrolidine, an important feedstock in the chemical industry, is commonly produced via vapor-phase catalytic ammoniation of tetrahydrofuran (THF). Obtaining pyrrolidine with high purity and low energy cost has extremely high economic and environmental values. Here we offer a rapid and energy-saving method for adsorptive separation of pyrrolidine and THF by using nonporous adaptive crystals of per-ethyl pillar[6]arene (EtP6). EtP6 crystals show a superior preference towards pyrrolidine in 50 : 50 (v/v) pyrrolidine/THF mixture vapor, resulting in rapid separation. The purity of pyrrolidine reaches 95% in 15 min of separation, and after 2 h, the purity is found to be 99.9%. Single-crystal structures demonstrate that the selectivity is based on the stability difference of host–guest structures after uptake of THF or pyrrolidine and non-covalent interactions in the crystals. Besides, EtP6 crystals can be recycled efficiently after the separation process owing to reversible transformations between the guest-free and guest-loaded EtP6.

中文翻译：

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柱[6]芳烃基无孔自适应晶体分离吡咯烷和四氢呋喃

吡咯烷是化学工业中的重要原料，通常通过四氢呋喃 (THF) 的气相催化氨化生产。获得高纯度、低能源成本的吡咯烷具有极高的经济和环境价值。在这里，我们提供了一种使用过乙基柱[6]芳烃 ( EtP6 )的无孔自适应晶体吸附分离吡咯烷和 THF 的快速且节能的方法。EtP6晶体在 50 : 50 (v/v) 吡咯烷/THF 混合物蒸气中表现出对吡咯烷的优越偏好，从而导致快速分离。分离15 min后吡咯烷纯度达到95%，分离2 h后纯度达到99.9%。单晶结构表明选择性是基于吸收 THF 或吡咯烷后主客体结构的稳定性差异以及晶体中的非共价相互作用。此外，由于无客体和载客 EtP6之间的可逆转变， EtP6晶体可以在分离过程后有效回收。