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

Abstract

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)3L3 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.

DSR: enhanced modelling and refinement of disordered structures with SHELXL

“…a high degree of structural flexibility paired with a limited resolution of the experimental data. DSR has already been successfully employed in that context Wise et al, 2015;Wood et al, 2015).…”

An Introduction to the Mechanical Bond

“…(Borromean Rings), 237 and 6 3 3 (cyclic [3]catenane) 238 have been reproduced (Figure 1.24) in the form of synthetic molecules-see Section 4.1.1.…”

“…Spacefilling representations of several of these novel topologies are presented in Figure 1.27. The collection includes examples of all of the synthetic prime links, 134,[236][237][238]266 composite links such as a [3]catenane, 123 [5]catenanesnamely, Olympiadane 133 and Kimoon Kim's 186 appropriately titled 'molecular necklace' 184 radial [5]catenane-as well as a branched [7] …”

Metal coordination as a template strategy to make resilient woven materials

“…knots, catenanes and rotaxanes) is well documented in the chemical literature. [1][2][3][4][5][6][7][8][9] The first proof-of-concept work in the field was reported in 1960 with the successful synthesis of a [2]catenane by statistical interlocking of molecular macrocycles. 10 In 1964, the first directed synthesis of a catenane was demonstrated by introducing a covalent template to bring the two molecular components in place.…”