Additive-CD-rotaxanes

It is possible to more effectively deliver small-molecule additives to polymers by employing either crystalline additive-CD-ICs or additives that are permanently complexed/rotaxanated with CDs and that remain soluble. Additive-CD-IC complexes may be delivered by melt-processing up to temperatures of 300°C, while the permanently threaded and soluble additive-CD-rotaxanes can be delivered from their solutions. 

CD-coat permits specific substrate targeting of the additive-CD-rotaxane, without the need to modify the chemistry of the additive itself. Together these advantages should soon lead to a new class of polymer and textile additives in the form of their CD-rotaxanes. 

Nanostructuring/Functionalizing Polymers via CD-IC Formation and Coalescence and Additive Delivery with Additive-CD-ICs and -Rotaxanes... 

The general procedure of delivering additives in the form of their CD-rotaxanes appears to offer improved solutions to a wide-range of polymer-additive and textilefinishing problems, because of two factors. First, CD-rotaxanation of an additive permits control of its solubility and offers protection (UV and chemical) to the threaded additive. Second, chemical modification of the hydroxyl groups on the... 

Figure 10.18. The acid/base-controlled switching of the [2]rotaxane 24 3PFf and the partial H-NMR spectra [400 MHz, (CD )2CO, 25 °C] of 24 3PF6 (a) before the addition of z-Pr2NEt, (b) after the addition of z-Pr2NEt and shuttling, and (c) after the addition of CF3C02H. The bipyridinium hydrogen atoms (H1 and HA) in the (3-positions with respect to the nitrogen atoms were used as the probe protons.

More recently, a similar approach was taken by Macartney and coworkers to synthesize [2]rotaxanes (Figure 4). Rotaxane 2 is self-assembled efficiently in solution from a-CD, [Fe(CN)5(H20)] and l,l -( f5 -alkanediyl)bis(4,4 -pyridyl-pyridium) ion. The [2]rotaxane is also formed by the addition of a-CD to a solution of the dumbbell component [(CN)5Fe(bpy(CH2)nbpy)Fe(CN)5]. This result infers a slow dissociation of the terminal metal complex, followed by formation of an intermediate pseudorotaxane and reassociation of the metal complex. 

More recently, the construction of a series a-CD [2]rotaxanes, based on the attachment of stoppers to threads by means of metal complex formation, was described by Macartney et al. [5] They have shown that the self-assembly of rotaxanes of the type [(NC)5Fe R(CH2) R - a-CD Fe(CN)5] -where R and R are bipyridinium or pyrazi-nium (e. g., 1 in Scheme 1) happens irrespective of the order of the addition of the components to the aqueous solution. This observation infers a slow dissociation of one of the [Fe(CN)s] ions, followed by a-CD inclusion and the recomplexation of [Fe(CN)s] ion. Evidence for the formation of [2]rotaxanes is provided by the H NMR spectra, in which the signals of the symme-... 

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