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Triangular Regulation of Cucurbit[8]uril 1:1 Complexes

Abstract : Triangular shapes have inspired scientists over time and are common in nature, such as the flower petals of oxalis triangularis, or the triangular faces of tetrahedrite crystals or on the icosahedron faces of virus capsids. Supramolecular chemistry has enabled the construction of triangular assemblies, many of which possess functional features. Among these structures, cucurbiturils have been used to build supramolecular triangles and we recently reported paramagnetic - cucurbit[8]uril (CB[8]) triangles but reasons of their formation remain unclear. Several parameters have now been identified to explain their formation. At first sight, the radical nature of the guest appeared of prime importance to get the triangles and we focused on extending this concept to biradicals for obtaining supramolecular hexaradicals. Two sodium ions were systematically observed by ESI-MS in trimer structures and the presence of Na+ triggered or strengthened the triangulation of CB[8]:guest 1:1 complexes in solution. X-ray crystallography and molecular modelling have allowed proposing two plausible sites of residence for the two sodium cations. We then found that a diamagnetic guest with an H bond acceptor function is equally good at forming CB[8] triangles. Hence, a guest molecule containing a ketone function has been precisely triangulated thanks to CB[8] and sodium cations as determined by DOSY-NMR and DLS. A binding constant for the triangulation of 1:1, to 3:3 complexes, is proposed. This concept has finally been extended to the triangulation of ditopic guests toward network formation by reticulation of CB[8] triangles using dinitroxide biradicals.
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https://hal-amu.archives-ouvertes.fr/hal-02355128
Contributor : Emilie Pepe <>
Submitted on : Friday, November 8, 2019 - 10:06:44 AM
Last modification on : Tuesday, November 26, 2019 - 4:12:09 PM

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Sébastien Combes, Khoa Truong Tran, Mehmet Menaf Ayhan, Hakim Karoui, Antal Rockenbauer, et al.. Triangular Regulation of Cucurbit[8]uril 1:1 Complexes. Journal of the American Chemical Society, American Chemical Society, 2019, 141 (14), pp.5897-5907. ⟨10.1021/jacs.9b00150⟩. ⟨hal-02355128⟩

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