Self-Assembly of Molecular Trefoil Knots Featuring Pentadecanuclear Homoleptic Au -, Au /Ag -, or Au /Cu -Alkynyl Coordination.

Metal-free and metal-containing molecular trefoil knots are fascinating ensembles that are usually covalently assembled, the latter requiring the rational design of di- or multidentate/multipodal ligands as connectors. In this work, we describe the self-assembly of pentadecanuclear Au trefoil knots [Au (C≡CR) ] from monoalkynes HC≡CR (R=9,9-X -fluorenyl with X=nBu, n-hexyl) and [Au (THT)Cl]. Hetero-bimetallic counterparts [Au M (C≡CR) ] (M=Cu/Ag) were self-assembled by reactions of [Au (C≡CR) ] with [Cu(MeCN) ] /AgNO and HC≡CR. The type of pentadecanuclear trefoil knots described herein is characterized by X-ray crystallography, 2D NMR and HR-ESI-MS. [Au Cu (C≡CR) ] is relatively stable in hexane; its excited state properties were investigated. DFT calculations revealed that non-covalent metal-metal and metal-ligand interactions, together with longer alkyl chain-strengthened inter-ligand dispersion interactions, govern the stability of the trefoil knot structures.