Interlocked structures self-assembly

Currently the main interest in template reactions lies in their key role in the controlled synthesis or the self-assembly of a variety of supramole-cular entities (449). One needs a combination of intuition, conjecture, and serendipity (450) a recent example of successfully combining serendipity and rational design is provided by the silver(I)-promoted assembly of one-dimensional stranded chains (451). One also needs an understanding of mechanism in order to optimize the selection and design of building blocks and templates for the generation of yet more sophisticated supramolecular structures references cited in this present review contain at least some kinetic or mechanistic information or speculation. Template routes to interlocked molecular structures have been reviewed (452), while a discussion of switching by transition metal contains a little about the kinetics and mechanisms of this aspect of template... 

A useful summary of the various and numerous types of rotaxanes, catenanes, and knots can be found in a review of template routes to interlocked molecular structures 468). Inorganic chemistry is centrally involved in the templating involved in self-assembly and in controlled synthesis of such species. 

Mechanically interlocked molecular compounds, including catenanes, rotax-anes, and carceplex, are constituted of molecules composed of two or more components that cannot be separated from each other [95-98]. The development of strategy for achieving controlled self-assembling systems by non-covalent interaction enables one to prepare such attractive compounds for applications in nanoscale molecular devices. The dithiafulvene derivatives are effective electron donors, which are good candidates to form those supramolecular systems with appropriate acceptors by virtue of intermolec-ular CT interactions. In this chapter, dithiafulvene polymers forming rotax-ane structures are especially described. 

Kim, Kimoon, Self-Assembly of Interlocked Structures with Cucurbituril Metal Ions and Metal Complexes, 5, 371. 

Scheme 1 The elegant 18-component self-assembly of molecular Borromean rings under thermodynamic control [156], which utilizes reversible imine bonds to incite self-correction of the iconic interlocked structure at equilibrium...

Our chief concern in this chapter will be with systems of this latter type. Namely, those that appear to involve a large measure of self-assembly during their formation - and for which some element of the templating interactions used to direct their construction remains within the interlocked final structures. However, it is still pertinent in the present context to survey briefly a selection of both the early and more recent statistical work. 

Stoddart and co-workers transferred the strategy of template-directed synthesis to the formation of the first molecular system consisting of five interlocked rings in a linear array (Structure 51). They suggested that this [5]catenane should be called olympiadane [64]. Recently they reported the self-assembly of a new type of rotaxane, in which three side chains are linked directly to a single central core, producing a dendritic-type structure [65]. 

Some of our recent work on the construction of interlocked structures is described in this short review. In the design of these structures, the barrel-shaped molecule cucurbituril is used as a molecular bead and metal ions or metal complexes are used as glue or angle connectors . The examples given here demonstrate the efficiency and control in the self assembly of highly organized supramolecular species. 

Self-Assembly of Interlocked Structures 2 SIMPLE ROTAXANES... 

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