Pseudo-polyrotaxane

Gibson et al. [109] and Sjen et al. [110] reported pseudo-polyrotaxanes and polyrotaxanes consisting of crown ethers with various polymers. The resulting polyrotaxanes were nonstoichiometric. Their properties - including solubility and glass transition temperatures - were different from those of the starting polymers. 

Further studies by the same authors have led to the formation of [2]rotaxanes, [3]rotaxanes and pseudo-polyrotaxanes [85-87]. In all these interlocked species, in spite of the presence of aromatic rings in the axle and wheel, tt-ti interactions do not seem to play a role in the templating process. This highlights once again the importance of C-H---0 hydrogen bonding in the assembly of interlocked species. 

Pseudo polyrotaxanes consist of low molecular weight rotaxanes which can assemble via non-covalent interactions. An illustrative example has recently been described by Stoddart, using a tetra-cationic bis(bipyridyl-phenyl)-cyclophane as macrocyclic ring component and phenylene-l,4-bis(oxy-oligoethyleneoxy)-co-carboxylic acid [385]. 

Figure 33 (a) Sketch of a pseudo-polyrotaxane from a bis(biphenyl-phenylene) cyclophane threaded on phenylene-l,4-bis(oxy(oligoethyleneoxy)carbonic acid), (b) Space filling model, calculated from crystal structure data [385], With permission of Wiley-VCH... 

Figure 6. Schematic representation of (a) pseudopolyrotaxanes [2a] and (b) a dendritic pseudo-polyrotaxane [15].

Pseudo)polyrotaxanes containing CB[6J threaded on organic polymers were also reported. Such (pseudo)poly-rotaxanes were synthesized by interfacial polymerization of CB[6]/polyamine pseudorotaxane with diacid chlorides such as 1,6-hexanedioyl chloride (adipoyl chloride). "" Steinke and coworkers recently reported a novel way to produce polyrotaxanes utilizing 1,3-dipolar cycloaddition between azide and alkyne inside the cavity of They also synthesized pseudopolyrotaxanes... 

Figure 28.6 Solution strategies to align rigid-rod conducting polymers into 2-D arrays by using supramolecular clips, followed by mechanical fixation through the formation of a pseudo-polyrotaxane. Questions have been asked regarding the feasibility of the selective sheet formation. RCM, ring-closing metathesis.

A rotaxane composed of many ring parts is referred to as a poly[ ]rotaxane [6] these, in turn, include mostly main-chain and side-chain polyrotaxanes (Figure 36.1). In main-chain polyrotaxanes, the ring components are threaded along a polymeric axle, to form a polymer of [2]rotaxanes. A variety of polymers can be used as the long axle molecules, ranging from polymethylene chains to aromatic polymers. Among the different types of side-chain polyrotaxane can be included pseudo-polyrotaxanes and poly(2]rotaxanes. 

Polymers containing CDs as side chains have been prepared and reported [17], and shown to form inclusion complexes with both small and large molecules to produce pseudo-polyrotaxanes [90]. The first side-chain polyrotaxanes were prepared by Ritter et al. in 1995 [91], whereby the guest parts were immobilized in the CD cavities by capping the end groups using triphenyl groups. 

The small multivalent enhancement observed in the agglutination assay for lactoside displayed covalently from a rigid polymer backbone contrasts with greater enhancements obtained (2, 4) for the flexible and ad table pseudo-polyrotaxanes. Interestingly, LCD alone displays a l.S-fold enhancement in efficacy over lactose, with an MIC (1000 pM) close to the valency-corrected MIC of the neoglycopolymer 2. We attribute this enhancement to a greater... 

Okumura, H. Okada, M. Kawaguchi, Y. Harada, A., Complex Formation Between Poly(dimethylsiloxane) and Cyclodextrins New Pseudo-Polyrotaxanes Containing Inorganic Polymers. Macromolecules 2000, 33,4297-4298. 

An alternative approach to side-chain (pseudo)polyrotaxanes involves the threading of acyclic monomeric components through the cavities of large rings appended to a polymeric backbone. 

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