Molecular knots

Knots are fascinating non-trivial topological entities. They are not only present in art and history but in many scientific fields as well, from mathematics to biology. By targeting this tantalizing structure, chemists have contributed to the promotion of their beauty. So far, two very different template syntheses of molecular knots have been developed. The first one is based on the template effect induced by a transition metal, which gathers and disposes fragments in a predictable geometry. The second relies on the use of a suitable hydrogen bond-set. Together with the presentation of these two reliable strategies, this chapter stresses one of the intrinsic properties of a knot: its chirality. The resolution of the two kinds of molecular knots into their enantiomers is discussed.