title: A synthetic molecular pentafoil knot.
abstract: Knots are being discovered with increasing frequency in both biological and synthetic macromolecules and have been fundamental topological targets for chemical synthesis for the past two decades. Here, we report on the synthesis of the most complex non-DNA molecular knot prepared to date: the self-assembly of five bis-aldehyde and five bis-amine building blocks about five metal cations and one chloride anion to form a 160-atom-loop molecular pentafoil knot (five crossing points). The structure and topology of the knot is established by NMR spectroscopy, mass spectrometry and X-ray crystallography, revealing a symmetrical closed-loop double helicate with the chloride anion held at the centre of the pentafoil knot by ten CH···Cl(-) hydrogen bonds. The one-pot self-assembly reaction features an exceptional number of different design elements-some well precedented and others less well known within the context of directing the formation of (supra)molecular species. We anticipate that the strategies and tactics used here can be applied to the rational synthesis of other higher-order interlocked molecular architectures.
authors.affiliation: School of Chemistry, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Ayme
authors.forename: Jonathon E
authors.initials: JE
authors.lastname: Beves
authors.forename: David A
authors.initials: DA
authors.lastname: Leigh
authors.forename: Roy T
authors.initials: RT
authors.lastname: McBurney
authors.forename: Kari
authors.initials: K
authors.lastname: Rissanen
authors.forename: David
authors.initials: D
authors.lastname: Schultz
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D007097:Imines / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D008024:Ligands; D046911:Macromolecular Substances / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry
chemical_list: D000447:Aldehydes; D000588:Amines; D002712:Chlorides; D007097:Imines; D008024:Ligands; D046911:Macromolecular Substances; D011725:Pyridines; D004247:DNA; D007501:Iron