Concyclic CH-π arrays for single-axis rotations of a bowl in a tube

Abstract

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.

The Supramolecular Chemistry of Strained Carbon Nanohoops

“… with permission from the American Chemical Society, Copyright (2015). c) Solid‐state structure of [4]CC ⊃( COR ) 2 , with the side chains of [4]CC omitted for clarity . d) Supramolecular interactions between alkoxy‐nanohoop 14 and cationic or neutral molecules .…”

Exploration of Nano‐Saturns: A Spectacular Sphere–Ring Supramolecular System

“…These dynamic properties are interesting in terms of the design of molecular bearings. Recently, [4]CC host was found to include a bowl‐shaped corannulene molecule via CH–π interactions with the guest molecule as a CH donor …”

Supramolekulare Chemie von gespannten Kohlenstoffnanoreifen

“… mit der Genehmigung der American Chemical Society, Copyright (2015). c) Festkörperstruktur von [4]CC ⊃( COR ) 2 , zur Verdeutlichung wurden die Seitenketten von [4]CC entfernt . d) Supramolekulare Wechselwirkung zwischen Alkoxy‐Nanoreifen 14 und kationischen bzw.…”

“…Über die reinen π‐π‐Wechselwirkungen hinaus entwickelte die Isobe‐Gruppe einen “Schüssel‐in‐Röhre”‐Wirt‐Gast‐Komplex, der auf überraschend starken CH‐π‐Wasserstoffbrücken basierte . Multivalente Wechselwirkungen eines schüsselförmigen Corannulens (Abbildung c; COR ) mit einem [4]CC ‐Nanoreifen führten zu einer weitgehend enthalpiegesteuerten 1:1‐Bindung ( K A =2.94×10 3 m −1 , DCM; isothermische Titrationskalorimetrie (ITC)).…”