Are the physical properties of Xe@cryptophane complexes easily predictable? the case of $syn$ and $anti$ tris-$aza$-cryptophanes
Résumé
We report the synthesis and the optical resolution of C3-symmetrical tris-azacryptophanes anti-3 and syn-4, as well as the study of their interaction with xenon via hyperpolarized 129 Xe NMR. These molecular cages are close structural analogs of the two wellknown cryptophane-A (1; chiral) and cryptophane-B (2; achiral) diastereomers since these new 2 compounds differ only by the presence of three nitrogen atoms grafted on the same cyclotribenzylene unit. The assignment of their relative (syn vs anti) and absolute configurations was made possible thanks to the combined use of quantum calculation at the DFT level and vibrational circular dichroism (VCD). More importantly, our results show that despite the large structural similarities with cryptophane-A (1) and-B (2), these two new compounds show very different behavior in the presence of xenon in organic solution. These results demonstrate that a prediction of the physical properties of the xenon@cryptophane complexes, only based on structural parameters, remains extremely difficult.
Domaines
Matériaux| Origine | Fichiers produits par l'(les) auteur(s) |
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