Barrow Steven J, Assaf Khaleel I, Palma Aniello, Nau Werner M, Scherman Oren A
Melville Laboratory for Polymer Synthesis , Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK . Email:
Department of Life Sciences and Chemistry , Jacobs University Bremen , Campus Ring 1 , D-28759 Bremen , Germany . Email:
Chem Sci. 2019 Oct 17;10(44):10240-10246. doi: 10.1039/c9sc03282g. eCollection 2019 Nov 28.
Whilst cucurbit[]urils (CB) have been utilized in gas encapsulation, only the smaller CB ( = 5 and 6) have utility given their small cavity size. In this work, we demonstrate that the large cavity of CB8 can be tailored for gaseous and volatile hydrocarbon encapsulation by restricting its internal cavity size with auxiliary aryl-bisimidazolium (Bis, aryl = phenyl, naphthyl, and biphenyl) guests. The binding constants for light hydrocarbons (C ≤ 4) are similar to those measured with CB6, while larger values are obtained with Bis·CB8 for larger guests. A clear propensity for higher affinities of alkenes relative to alkanes is observed, most pronounced with the largest delocalized naphthalene residue in the auxiliary Bis guest, which provides unique evidence for sizable small-molecule π-π interactions.
虽然葫芦脲（CB）已被用于气体封装，但由于其腔体尺寸较小，只有较小的CB（=5和6）具有实用性。在这项工作中，我们证明了通过用辅助芳基双咪唑鎓（Bis，芳基=苯基、萘基和联苯基）客体限制其内部腔体尺寸，CB8的大腔体可用于气态和挥发性烃类的封装。轻质烃（C≤4）的结合常数与用CB6测得的相似，而对于较大的客体，Bis·CB8获得了更大的值。观察到烯烃相对于烷烃具有更高亲和力的明显倾向，在辅助Bis客体中具有最大离域萘残基时最为明显，这为相当大的小分子π-π相互作用提供了独特的证据。
