Threading/dethreading

Because these approaches can often be equally well applied to the shuttling motion of rotaxanes, the circumrotation of catenanes, and the threading/dethreading of pseudorotaxanes, we do not restrict this discussion to rotation only, but present a small selection of different examples. 

Fig. 7 Molecular-level plug/socket system for energy transfer based on the reversible acid-base driven threading-dethreading motions in the hydrogen bonded pseudorotaxane 4d5H+ (CH2C12 room temperature). The acid-driven threading of compound 6, incorporating a bulky benzyl group, through the macrocyclic cavity of 4 does not occur [57]...

Figure 15. The electrochemically induced threading/dethreading processes associated with pseudo-rotaxane [26-27]2+ (HjO, pH 7, 298 K) [44],...

Figure 27. Reversible threading/dethreading of compound 34 upon acid/base stimulation (CH2CI2, 298 K) [69].

Figure 35. Schematic representation of the threading/dethreading pattern of [2]pseudorotaxane [37c38]2, which corresponds to an XOR logic function.

Figure 16 Threading-dethreading of pseudorotaxane [28 C 29] + as a consequence of the cis-trans photoisomerization of the azobenzene unit contained in the thread-like component 28. ...

Figure 22 (a) The acid-base controlled threading-dethreading of pseudorotaxane [34 D 35-H] +. (b) The acid-base and light... 

Figure 23 Scheme of threading-dethreading processes in pseudorotaxane [34 d 35-H] + controlled by means of photoinduced proton exchange with the photochromic system 36/37-H+. ° ... 

Fig. 29.5 (Top) Schematic representation of the possible self-assembly processes in weakly polar solvents between wheel 4 and non-symmetric axles C5Cn (n = 8, 10, 12 and 18) to yield oriented pseudorotaxane isomers P[4 D C5Cn],j ,(,rt and P[4 D C5Cn] o (bottom) threading/dethreading equilibria of the two pseudorotaxane isomers dashed lines represent lower-rim threading processes that do not occur under our conditions (Adapted with permission from Ref. [29], copyright 2013 American Chemical Society)...

Scheme 7.1 Control of threading-dethreading jaecesses in pseudorotaxane [C AH] by means of light-induced proton exchange with a spiropyran-merocyanine photochromic system...

In conclusion, we have shown that the threading-dethreading of a pH-switchable calix[6]arene bipyridinium pseudorotaxane in solution can be controlled by visible... 

Pseudorotaxanes complexes can be rendered kinetically inert, i.e. transformed into rotaxanes, by attaching bulky groups at the extremities of the axle to prevent dethreading [1]. Therefore, the pseudorotaxane or rotaxane behavior of a given axle-macrocycle pair depends on the threading-dethreading rate constants, which in turn are determined by the intrinsic kinetic parameters of such processes— particularly, the energy barriers—and the experimental conditions [2, 3],... 

Scheme 8.1 Representation of the chemical equilibria and photochemical reactions involving components IH and 2 and simplified potential energy curves (free energy versus ring-axle distance) for the threading-dethreading of the ring and the axle in its EE left) and ZZ (right) isomeric forms...

---