Two-stage directed self-assembly of a cyclic [3]catenane

• Published in: Nature chemistry Vol. 7; no. 4; pp. 354 - 358
• Main Authors: Wood, Christopher S., Ronson, Tanya K., Belenguer, Ana M., Holstein, Julian J., Nitschke, Jonathan R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-04-2015; Nature Publishing Group
• Subjects: 140/131; 140/58; 639/638/541/966; Analytical Chemistry; Biochemistry; Chemistry; Chemistry/Food Science; Inorganic Chemistry; Organic Chemistry; Physical Chemistry
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.2205

Interlocked molecules possess properties and functions that depend upon their intricate connectivity. In addition to the topologically trivial rotaxanes, whose structures may be captured by a planar graph, the topologically non-trivial knots and catenanes represent some of chemistry's most challenging synthetic targets because of the three-dimensional assembly necessary for their construction. Here we report the synthesis of a cyclic [3]catenane, which consists of three mutually interpenetrating rings, via an unusual synthetic route. Five distinct building blocks self-assemble into a heteroleptic triangular framework composed of two joined Fe
II
3
L
3
circular helicates. Subcomponent exchange then enables specific points in the framework to be linked together to generate the cyclic [3]catenane product. Our method represents an advance both in the intricacy of the metal-templated self-assembly procedure and in the use of selective imine exchange to generate a topologically complex product.
Interlocked molecules represent some of the most challenging synthetic targets in terms of non-natural products. It has now been demonstrated how a cyclic [3]catenane composed of three mutually interpenetrating rings can be prepared in two stages using a selective imine exchange reaction on a self-assembled triangular precursor.