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  • An Inherently Chiral Au24 F...
    Sugiuchi, Mizuho; Shichibu, Yukatsu; Konishi, Katsuaki

    Angewandte Chemie International Edition, June 25, 2018, Letnik: 57, Številka: 26
    Journal Article

    2,3‐bis(diphenylphosphino)butane enantiomers (chiraphos, L) used as chiral auxiliaries results in the preferential formation of an unprecedented Au24 framework with inherent chirality. The crystal structure of Au24L6Cl42+ (1) has a square antiprism‐like octagold core twinned by two helicene‐like hexagold motifs, where the inherent chirality is associated with the helical arrangement. The clusters carrying (R,R)‐ and (S,S)‐ diphosphines had right‐ and left‐handed strands, respectively. Circular dichroism spectra showed peaks in the visible to near‐IR region, some of which did not coincide with absorption bands, suggesting the enantiomeric Au24 frameworks possess unique chiroptical properties. The Au24 frameworks were thermally robust, which could be attributed to the superatomic concept (18 e− system) and the steric constraint effects of the bridging ligand units. Hexagold strands: An unprecedented Au24 framework with inherent chirality was synthesized by the use of optically pure chiraphos ligands. The chiral structure was characterized by the duplex of 6‐helicene‐like hexagold strands twinning around the square antiprism‐like octagold core. The enantiomeric clusters showed characteristic circular dichroism responses in the visible to NIR region.