Upon encapsulating an oval‐shaped hydrocarbon guest, a cylindrical host deforms its shape to maximize intermolecular contacts. Structure–assembly relationship studies with a series of hydrocarbon guests disclosed the importance of molecular shapes and CH–π contacts. Multiple contacts and weak CH–π hydrogen bonds resulted in an optimal assembly; however, the shape deformation resulted in severe retardation of rotational motions in the crystal. Thus, unlike a circular guest, the oval‐shaped guest did not change its orientation in the host. Unexpectedly, the planar guest did not affect the packing structure to form a double helix in intertwined host arrays.
The hydrogen bond is undoubtedly one of the most important non-covalent interactions. Among the several types of the hydrogen bonds, the CH–π interaction is a relatively new notion that is being recognised in chemistry and biology. Although the CH–π hydrogen bond and conventional hydrogen bonds share common features such as directionality, this weak interaction has played a secondary role in molecular recognition. In this study, we have devised a host–guest complex that is assembled solely by the CH–π hydrogen bonds. Multivalent interactions of a bowl-shaped hydrocarbon with its peripheral hydrogen atoms are made possible via CH–π hydrogen bonds by adopting a tubular hydrocarbon as a host for their enthalpy-driven complexation. Concyclic arrays of weak hydrogen bonds further allow dynamic rotational motions of the guest in the host. Solid-state analysis with crystallographic and spectroscopic methods reveal a single-axis rotation of the bowl in the tube.
Upon encapsulating an oval-shaped hydrocarbon guest, ac ylindrical host deforms its shape to maximize intermolecular contacts.Structure-assembly relationship studies with as eries of hydrocarbon guests disclosed the importance of molecular shapes and CH-p contacts.M ultiple contacts and weak CH-p hydrogen bonds resulted in an optimal assembly;however,the shape deformation resulted in severe retardation of rotational motions in the crystal. Thus, unlike acircular guest, the oval-shaped guest did not change its orientation in the host. Unexpectedly,the planar guest did not affect the packing structure to form ad ouble helix in intertwined host arrays.
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