Rotaxanes 3 -rotaxane

Another synthetic strategy is based on self-assembly driven by molecular recognition between complementary TT-donors and 7T-acceptors. Examples include the synthesis of catenanes and rotaxanes that can act as controUable molecular shuttles (6,236). The TT-donors in the shuttles are located in the dumb-beU shaped component of the rotaxane and the 7T-acceptors in the macrocycHc component, or vice versa. The shuttles may be switched by chemical, electrochemical, or photochemical means. 

Catenanes and rotaxanes including macroheterocyclic fragments 99T5265. 

Rotaxanes with macroheterocyclic components as new architectures for pho-toinduced electron transfer and motions 99CSR293. 

Template synthesis and chirality of catenanes, rotaxanes, and pretzelanes including N-macroheterocyclic lactams and related compounds as structure components 99PAC247. 

Intramolecular mobility of metal complexes of rotaxanes and catenanes with macroheterocyclic fragments 98ACR611. 

Molecular movements in pseudorotaxanes,rotaxanes,andcatenanes with macroheterocyclic fragments 98ACR405. 

Nonionic template synthesis of amide-linked catenanes and rotaxanes with macroheterocyclic fragments 97AG(E)930. 

Self-assembly in construction of pseudorotaxanes, rotaxanes, and catenanes with crown ether fragments 98PAC419. 

As discussed in Section 7.3, conventional free radical polymerization is a widely used technique that is relatively easy to employ. However, it does have its limitations. It is often difficult to obtain predetermined polymer architectures with precise and narrow molecular weight distributions. Transition metal-mediated living radical polymerization is a recently developed method that has been developed to overcome these limitations [53, 54]. It permits the synthesis of polymers with varied architectures (for example, blocks, stars, and combs) and with predetermined end groups (e.g., rotaxanes, biomolecules, and dyes). 

In the first paper on arenediazonium salt/crown ether complexes, Gokel and Cram (1973) mention that they were not able to synthesize the rotaxane 11.14 by an azo coupling reaction of the complexed diazonium ion with Af,Af-dimethylaniline. 

Swager et al. prepared conjugated polymers with tethered rotaxane groups [76]. As a substrate, a rotaxane containing a diiodobiphenyl unit was synthesized for this purpose. Polymerization via microwave-assisted Sono-... 

These compounds contain two or more independent portions that are not bonded to each other by any valence forces but nevertheless must remain linked. Catenanes are made up of two or more rings held together as links in a chain, while in rotaxanes a... 

For a monograph, see Schill, G. Catenanes, Rotaxanes, and Knots Academic Press NY, 1971. For a review, see Schill, G. in Chiurdoglu Conformational Analysis Academic Press NY, 1971, p. 229. 

Schemes of this type were carried out by Harrison, I.T. Harrison, S. J. Am. Chem. Soc., 1967, 89, 5723 Ogino, H. J. Am. Chem. Soc., 1981, 103, 1303. For a different kind of statistical synthesis of a rotaxane, see Harrison, I.T. J. Chem. Soc., Perkin Trans. 1,1974, 301 Schill, G. Beckmann, W. Schweikert, N. Fritz, H. Chem. Ber, 1986,119,2647. See also Agam, G. Graiver, D. Zilkha, A. J. Am. Chem. Soc., 1976, 98, 5206.

This molecule has no chiral carbons, nor does it have a rigid shape, but it too has neither a plane nor an alternating axis of symmetry. Compound 32 has been synthesized and has, in fact, been shown to be chiral. Rings containing 50 or more members should be able to exist as knots (33, and see 37 on p. 114 in Chapter 3). Such a knot would be nonsuperimposable on its mirror image. Calixarenes, ° crown ethers, catenanes, and rotaxanes (see p. 113) can also be chiral if suitably substituted. For example, A and B are nonsuperimposable mirror images. 

The synthesis of [3]- (figuratively shown as 7) and a [5]rotaxane (8) with one central and two terminal porphyrins in the open configuration has been reported <96AG(E)906> also a rotaxane with two Ru(terpy>2 stoppers has appeared <96CC1915>. A pseudorotaxane comprised of a macroring of 2,9-diphenyl-1,10-phenanthroline unit and a molecular string... 

Schalley CA, WeUandt T, Briiggemann J,V6gtle F (2004) Hydrogen-Bond-Mediated Template Synthesis of Rotaxanes, Catenanes, and Knotanes. 248 141-200 Scheer M,see Balazs G (2003) 232 1-23... 

Keywords. Rotaxane dendrimers. Host-guest interaction, Recognition, Self-assembly, Supra-molecular chemistry... 

Dendrimers with a Rotaxane Core Type I Rotaxane Dendrimers. .. 117... 

Rotaxane Dendrimers Bearing Dendron Stoppers Type I-A.117... 

Rotaxane Dendrimers with Dendron Units Attached to the Ring ... 

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

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