Self-assembly of catenanes

Successful self-assembly of catenanes 23 and 25 and their remarkable stability imply that rectangular box structures for the component rings are very effective for catenation. Thus, we also designed the construction of rectangular frameworks from a set of 11 and two different ligands. Surprisingly, these three-component systems worked very well and we observed highly efficient three-component-... 

Interestingly, the self-assembly of catenanes was also observed from a three-component system. Three components, la, 2, and 34, self-assembled in water in a 2 1 1 stoichiometry to give catenane 35 in very high quantitative yield of 94% (Scheme 12). The structure of 35 was conformed by X-ray crystallography (Figure 8), ESI-MS, and NMR. It is noteworthy that the thermodynamic stability of 35 overcomes the combination problem which arises in the self-assembly of larger sets of components. At least, the formation of the three component macrocycles 3a, 36, and 37 is possible because their thermodynamic stability is comparable with that of 35. Further, the formation of more flexible and expanded catenane 40 was also observed when the components la, 38, and 39 were combined in water in 2 1 1 ratio (Scheme 13). The structure of 34 was deduced from an ESI-MS study. 

Self-assembly of [2]catenanes containing metals in their backbones 99ACR53. 

A review13 with 53 references of the transition-metal mediated supramolecular self-assembly is presented. Focus is on the self-assembly of macrocycles, catenanes, and cages from (en)Pd(N03)2 and pyridine-based bridging ligands. 

Very large organogold rings (16), as well as the related dimeric [2]catenane, have been generated by the self-assembly of complex digold(I) diacetylide with a diphosphane ligand <00AG(E)3819>. 

Figure B. Pictorial representation of the self-assembly of pseudorotaxa-nes based on (a) charge-transfer and C-H—O hydrogen-bonding interactions between 1,1 -diben-zyl-4,4 -bipyridinium dication and 1,5-dinaphtho[38] crown-10 (1/5DN38C10), and (b) hydrogen-bonding interactions between dibenzyl ammonium ion and dibenzo[24]crown-8 (DB24C8). A possible route towards the synthesis of rotaxanes and catenanes is also schematized.

P.R. Ashton, R. Ballardini, V. Balzani, A. Credi, M. T. Gandolfi, D. J.-F. Marquis, S. Menzer, L. Perez-Garcia, L. Prodi, J. E Stoddart, M. Venturi, A. J. P. White, D. J. Williams, The Self-Assembly of [2]Catenanes Incorporating Photo-Active and Electro-Active re-Extended Systems , J. Am. Chem. Soc 1995,117,11171-11197. 

Another fascinating approach to catenanes via self-assembly involves metal-coordination which templates or directs the assembly of catenane frameworks. After brief discussions on the recent examples of metal-containing catenanes and related topologically interesting molecules (Sections 4.2.1-4.2.3), the focus will be on the self-assembly of Pd(II)-linked catenanes (Sections 4.2.4 and 4.2.5). 

Electronic Effects in the Self-Assembly of Pd(n)-Linked Catenanes... 

Another question on the self-assembly of metal-linked catenanes is whether it is possible to design various catenane molecules rationally on the basis of the same principle. To elucidate the major factors that control the self-assembly of inter-... 

From the results summarized in Table 1 we can conclude that the self-assembly of Pd(II)-linked catenanes is predictable. When the component rings have a cavity with an appropriate interplane distance (ca. 3.5 A), catenanes are obtained efficiently (e.g. from ligands 12, 22, 24, 26+27, or 29+30). If, however, the cavity is too large or too small, catenanes are not assembled (e.g. from 26, 27, 35, or 36). Thus two conditions must be satisfied if metal-incorporating catenanes are to be obtained by self-assembly. Firstly, component rings should contain reversible coordinate bonds. Second, both component rings should have interplane separation of approximately 3.5 A in the cavity. 

Figure 25. The self-assembly of the neutral [2]catenanes 73 and 74 and the solid state structure of the [2]catenane 73.

Fujita, M., Self-assembly of [2]catenanes containing metals in their backbones. Acc. Chem. Res. 1999, 32, 53-61. 

Figure 15. Self assembly of a [2]catenane using a metal-ion template effect.

Metal-directed Self-assembly of Cryptands and Catenanes Using the Dithiocarbamate Ligand... 

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