Pseudo-rotaxane

Pseudo)rotaxane-Terminated Dendrimers with Covalently-Attached... 

Dendrimers with (pseudo)rotaxane-decorated periphery (Pseudo)rotaxane-terminated dendrimers with covalently-attached rod components at the periphery... 

Pseudo)rotaxane-Terminated Dendrimers with Covaientiy-Attached Rod Components at the Periphery Type ii-A... 

The versatility and reversibility of exo-active surfaces have been further explored by using pseudo-rotaxane architectures. Pseudo-rotaxanes generated from the electron-deficient cyclophane cyclobi s(paraquat-p-phenylene) (CBPQT4 +) (3) and... 

Cooke and coworkers incorporated pseudo-rotaxanes on the periphery of a NP as a means of reversibly modifying NPs structure and function.44 MMPCs featuring... 

More recently, Harada et al. applied the complexation process to side-chain systems via Method 6 (Figure 10), in which the guest sites were introduced as pendant groups and thereafter the CD was threaded onto them [104, 105]. Different types of hydrocarbon chain as pendant groups were studied for their compatibility with different CDs. As the cyclic was not blocked, the products can be viewed as side-chain poly(pseudo rotaxane)s of Type 9. Probably because of the rapid exchange process between threaded and unthreaded forms, the isolation of the solid-state polyrotaxane was not reported. 

PDMS chains have also been threaded through cyclodextrins, to form pseudo-rotaxanes.108... 

Fig. 94. Macrocycle (top) used to host the lanthanide-containing pseudo-rotaxane threads (middle and bottom)...

The binding of ammonium ion, NH4+, by 18-crown-6 was demonstrated early in the history of macrocycle chemistry. The O-H-N in crowns or N-H-N interaction in azacrowns has been characterized by a variety of techniques, including NMR, calorimetry, and X-ray crystal structure analysis. Recent studies in this area have shown that both quaternary and secondary ammonium salts can form complexes with crowns. In the latter case, a rotaxane molecule was prepared by treatment of a dibenzylammonium salt with dibenzo-24-crown-8 and other macrocycles, including pyrido-24-crown-8. The solid-state structure of the pseudo-rotaxane structure obtained with pyrido-24-crown-8 is shown in the left panel of Figure 23. 

A similar concept has been applied to the switching of a macrocyclic component 3 between two different co-ordination sites on the linear component 26 to yield the corresponding pseudo-rotaxane." A subsequent report describes parallel studies involving an analogous [2]-rotaxane (incorporating bulky terminal mesylate... 

Figure 6.13 A pseudo-rotaxane capable of switching between two arrangements under redox control ...

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

Figure 1. Schematic representation of (a) [2]pseudo-rotaxanes, (b) [2]rotaxanes, and (c) [2]catenanes.

Photoisomerizations can often occur by several different mechanisms. Systems that isomerize via a controlled mechanism are potential candidates for molecular machines [184]. Energy in the form of light is absorbed and converted to controlled mechanical force on the molecular scale. Examples of a mono-directional rotor [185, 186], a switchable rotor [187], and a molecular shuttle [188] have been demonstrated. These systems are light-controlled, but there are also examples of systems which control molecular motion based on electro- and/or chemical modulation, such as the threading/imthreading of (pseudo)rotaxanes [189-196]. 

N. Zaggheroni, Heterosupramolecu-lar Chemistry Programmed Pseudo-rotaxane Assembly at the surface of a nanocrystal. Angew. Chem. Int. Ed. 

Fig. 4 Illustrative structure of the pseudo-rotaxane complex formed between Kim s diaminobu-tane dendrimer and 32 CB6 hosts...

Fig. 6. Metadynamics error on the free energy for the pseudo-rotaxane naphthalene complex as a function of the run number. Upper panel, the error computed by (11) (dashed line with circles) and the error predicted by (28), including the correction factor for a finite tg derived in [56] (continuous line with diamonds). Lower panels-. the metadynamics parameters w, Ss and tg as a function of the rnn nnmber. After [56]...

Fig. 8. Accuracy of the reconstructed FES as a function of the number of walkers on the free energy for the pseudo-rotaxane naphthalene complex (see Sect. 3.1 for details on the system). The accuracy is measured with (11) when the first walker escapes from the associated state and, for every value of Nw, is averaged over ten independent simulations. The horizontal line corresponds to the accuracy predicted by (28). After [59]...

Entangled systems are extended arrays, more complex than their constituents, that are comprised of individual motifs forming, via interlocking or interweaving, periodic architectures infinite in at least one dimension. Simple interdigitation is not considered here. As previously stated, most of the entangled arrays can be considered regularly repeated infinite versions of finite molecular motifs like catenanes, rotaxanes and pseudo-rotaxanes. 

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