A ‘Texas-sized’ molecular box that forms an anion-induced supramolecular necklace

Abstract

The ‘blue box’ (cyclobis(paraquat-p-phenylene) or CBPQT4+), developed by Stoddart and colleagues, forms effective charge transfer complexes with a variety of electron-rich species and has been used to support the formation of a wide range of interlocked structures. However, little effort seems to have been devoted to generalizing the blue box concept. We describe a new flexible tetracationic macrocycle—a ‘Texas-sized’ molecular box. This positively charged receptor is capable of binding the mono-terephthalate anion, forming pseudorotaxanes. These pseudorotaxanes self-assemble into short supramolecular pseudo-oligorotaxanes in solution and more extended pseudo-polyrotaxanes in the solid state. The supramolecular oligomers formed in solution are environmentally responsive; they undergo deaggregation as the overall concentration of the cationic and anionic constituents is reduced, the temperature is increased, or the protonation state of the threading mono-terephthalate anion is changed. Macrocyles capable of hosting other molecules inside their hollow interiors have been used extensively to make threaded complexes and interlocked molecules. Now, a relatively large and flexible tetracationic macrocycle has been shown to bind anionic guests to form pseudorotaxanes that form extended structures in solution and the solid state.

Cite this article

Gong, HY., Rambo, B., Karnas, E. et al. A ‘Texas-sized’ molecular box that forms an anion-induced supramolecular necklace. Nature Chem 2, 406–409 (2010). https://doi.org/10.1038/nchem.597

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