Catenane exchange processes

A variable temperature H NMR study of the above compound has been undertaken. Despite the presence of a surfeit of exchange processes, it was concluded that this [2]-catenane is a highly ordered molecular assembly in solution. ... 

Figure 13.14 Dynamic processes associated with circumrotation of one ring in a catenane made of two different macrocycles, each incorporating two identical recognition sites. Asterisks are used to highlight the exchange of position of identical units.

Detailed electron- and energy-transfer studies have been carried out, on the copper(I) complexes, on the demetalated species and, in some cases, on complexes obtained by exchanging the copper center for another cationic metal (Li, Ag" "). The photophysical properties have been studied in different solvents, however, being solvents of similar polarity, the results for different systems can be considered comparable. Time-resolved measurements allowed us to analyze in detail several electron and energy transfer processes occurring in cascade in some of the highly multicomponent catenanes and rotaxanes of the present article. In addition, it has been possible to identify very distinct conformers in solution, some of them containing two chromophores located close to one another and others with remote chromophores. 

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