The formation of chiral supramolecular structures by coordination chemistry is rapidly evolving, with applications such as chiral recognition and asymmetric catalysis.[1] While in most cases the moieties endowing chirality are peripherally attached, there are limited examples where the enantiopure moieties are directly embedded in the backbone.[2]Recently, we introduced oligomers consisting of enantiopure alleno-acetylenes, which display significant nonlinear amplification of chiroptical properties with increasing number of chromophoric repeat units. This nonlinear increase is explained by the formation of a secondary helical structure.[3] It was thus of great interest to explore the chiroptical properties of conformationally-stable supramolecular structures containing enantiopure allenes-acetylenes.Herein we present the first supramolecular coordination structures containing enantiopure alleno-acetylenes in the backbone, which selectively form double-stranded or triple-stranded helicates. The X-ray structure of the triple-stranded helicate reveals a chiral cavity for potential encapsulation of small molecules. The chiroptical properties of the supramolecular structures along with TD-DFT calculations are discussed.References[1] Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Chem. Rev. 2011,  111, 6810-6918.[2] Bunzen, J.; Bruhn, T.; Bringmann, G.; Lutzen, A. J. Am. Chem. Soc. 2009,  131, 3621-3630.[3] Rivera-Fuentes, P.; Diederich, F. Angew. Chem. Int. Ed. 2012,  51, 2818-2828.

Supramolecular helicates with enantiopure alleno-acetylenes

248th National Meeting (2014)

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