Pseudorotaxane moiety

Kim et al. discovered a method of reversibly fixing pseudorotaxane moieties to the outer shell by non-covalent interactions (Fig. 6.9). The prefix pseudo de-... 

Random polynorbomene-based terpolymer 5 (Fig. 5.8) functionalized with SCS palladated pincer complexes, dibenzo[24]crown-8 (DB24C8) rings, and 2,6-diaminopyridine units was synthesized by ROMP (South et al. 2006). The palladium complex serves as the anchoring unit for metal coordination, 2,6-diaminopyridine as the DAD hydrogen bonding moiety, and DB24C8 as the precursor for pseudorotaxane formation, which has been smdied extensively by Stoddart and his group... 

Gibson et al. recently demonstrated that a pseudorotaxane-like linear assembly can be synthesized from a bis crown ether moiety and a bis ammonium salt... 

Four donor acceptor [2]catenanes possessing cyclobis(paraquat-p-phenylene), as the 7i-electron acceptor, and 1,5-dioxynaphthalene-containing macrocyclic polyethers, as the 7i-electron donor moieties, have been constructed employing Cu+-catalyzed Huisgen 1,3-dipolar cycloaddition and Cu+2-mediated Eglinton coupling condition in the final step <07JA8236>. Desymmetrized [2]catenanes were synthesized by means of a template synthesis of pseudorotaxanes between 7i-rich crown ethers and a 7i-deficient pyromellitic subunit,... 

Several bis(/ -phenylene)-32-crown-10-based cryptands with a variety of different moieties on the third bridge, best represented by 121, have been studied with respect to their ability to form with paraquat and bisparaquat derivatives [2]- and [3]pseudorotaxane-like structures. These inclusion complexes are observed both in the solid state (X-ray analysis) and in solution, where very high association constants have been measured by means of H NMR spectroscopy <19990L1001, 2003JA9272, 2005JOC3231, 2006CC1929>. 

Figure 8. Examples of pseudorotaxane components containing units capable of exhibiting specific properties, (a) A wire with an ammonium function and a photoactive anthracene as a stopper [17b] (b) a bipyridinium-type wire with a photo- and redox-active Ru(bpy)j + moiety [18] (c) a crown ether incorporating a binaphthyl unit [19] (d) a cyclophane containing a Re complex and two bi-pyridinium units (20. ...

Figure 5. Some pseudorotaxane components containing units capable of exhibiting specific properties. The wirelike molecule 11H+, with an ammonium center and a photoactive anthracene unit as a stopper [40] the bipyridinium-containing wire 12 +, with a photo- and redox-active [Ru(bpy)3]2+ moiety [41] crown ether 13, incorporating a binaphthyl unit [42] cyclophane 14 +, which contains a [Ru(bpy)3]2+ complex and...

The plug/socket concept has recently been used to design and construct a self-assembling [3]pseudorotaxane that mimics at the molecular level the function played by a macroscopic extension. The system is made (Fig. 33) [140] of three components, 35 +, 36H +, and 2. Component 35 + consists of two moieties—a [Ru(bpy)3]2+ unit, which plays the role of electron donor under light excitation, and a... 

Figure 33. Supramolecular system that mimics the function played by a macroscopic extension [140]. The two pseudorotaxane-type connections between the three molecular components can be controlled independently by acid/base and red/ox stimulation, respectively. In the fully assembled [3]pseudorotaxane, a photoinduced electron transfer process occurs from the excited state of the [RLiibpy) moiety of 35 to the bipyridinium unit of 36H +, which, in turn, is plugged into crown ether 2.

Cucurbituril, Its Homologues, and Derivatives, p. 390 The Diphenylmethane Moiety, p. 452 Interpenetration, p. 735 Macrocycle Synthesis, p. 830 Rotaxanes and Pseudorotaxanes. p. 1194 Self-Assembly Definition and Kinetic and Thermodynamic Considerations, p. 1248 Self-Assembly Terminology, p. 1263 Strict Self-Assembly and Self-Assembly with Covalent Modifications, p. 1372 The Template Effect, p. 1493... 

Variations in monomer and catalyst stoichiometry, reaction time or temperature all proved unsuccessful in triggering the formation of the dipolar cycloaddition product. The use of excess cucurbituril led only to quantitative isolation of the pseudorotaxanes derived from 1 and 2 (Fig. 1.38). We speculated that our initial monomer design must have been flawed. The choice of a six-carbon spacer to maximize recognition of the monomer by cucurbituril may be the cause of the catalytic inhibition. We hypothesized that the pseudorotaxanes derived from cucurbituril and monomers 1 and 2 must form much faster than any possible ternary complex and that the essentially perfect fit of each monomer inside cucurbituril would prevent the simultaneous encapsulation of alkyne and azide moieties by a third cucurbituril with the correct conformation required for catalysis. 

A series of diamide-based cryptands derived from bis(m-phenylene)-[32]crown-10 have been synthesized to complex divalent salts such as paraquat (N,N-dimethyl-4,4 -bipyridinium) dichloride. The synthetic project started from the observation that readily prepared bicyclic crown ether 23 containing two 1,3,5-phenylene units linked by three tetra(ethyleneoxy) units forms a pseudorotaxane-like inclusion complex with Af,Af-dimethyl-4,4-bipyridinium bis(hexafluorophosphate), with an association constant /fa = 6.1 X 1() M that is 100-fold greater than that of the analogous simple crown ether. On this basis, additional anion-binding moieties, such as isophthalamide or 2,6-pyridinedicarboxamide unit, were intfoduced in the third chain of the cryptand receptor. The anion-assisted complexation of bypyridinium dications was analyzed by a combination of different techniques ( H NMR,... 

---