Precision synthesis of linear oligorotaxanes and polyrotaxanes achieving well-defined positions and numbers of cyclic components on the axle

Masai, Hiroshi; Oka, Yuki; Terao, Jun

doi:10.1039/d1cc03507j

Cited by 14 publications

(10 citation statements)

References 120 publications

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“…The synthetic challenges snowball when it comes to the precise syntheses of polyrotaxanes, 59,61,72,73,138 especially when the aim is to achieve absolute control over the constitution, number, position and sequence of the threaded rings. This challenge arises from the rapid dynamic threading and de-threading processes that take place in solution, making it difficult to prepare polyrotaxanes whose binding sites are all occupied by particular rings, even when the threading propensity of rings onto dumbbell precursors is high.…”

Section: Synthetic Approaches For Homogeneous Polyrotaxanesmentioning

confidence: 99%

Sequence‐controlled synthesis of rotaxanes

Han

Seale

Feng

et al. 2023

Journal of Polymer Science

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Rotaxanes with well-defined ring sequences are attractive synthetic goals in the construction of functional materials associated with molecular shuttles and switches, molecular electronics, and information storage. Sequencecontrolled synthesis of oligo-and polyrotaxanes is important in the context of the development of both sequence-defined polymers and dynamic functional materials. To date, examples of sequence-controlled rotaxanes are limited to oligorotaxanes on account of the synthetic challenges they pose. This Review sheds light on the pivotal role that sequence isomerism plays in rotaxanes.Synthetic approaches, including orthogonal templation, active-metal templation, self-sorting and snapping, cooperative-capturing, ring-through-ring-shuttling, and molecular pumping, for the construction of sequence-controlled rotaxanes are all discussed in this Review. By comparing the advantages and disadvantages of these different approaches, several possible synthetic strategies are proposed in an attempt to foretell the future of sequence-controlled synthesis of polyrotaxanes.

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Section: Synthetic Approaches For Homogeneous Polyrotaxanesmentioning

confidence: 99%

Sequence‐controlled synthesis of rotaxanes

Han

Seale

Feng

et al. 2023

Journal of Polymer Science

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“…In this way, molecular pumping also enables the synthesis of well-defined higher order oligo- and polyrotaxanes and catenanes that would be inaccessible through conventional “passive” template synthesis. 13 , 18 , 28 − 32 …”

Section: Introductionmentioning

confidence: 99%

“…Each pumping cycle builds on the last by increasing the concentration of macrocycles held on the collection thread. In this way, molecular pumping also enables the synthesis of well-defined higher order oligo- and polyrotaxanes and catenanes that would be inaccessible through conventional “passive” template synthesis. ,,− …”

Section: Introductionmentioning

confidence: 99%

Transamidation-Driven Molecular Pumps

et al. 2022

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We report a new class of synthetic molecular pumps that use a stepwise information ratchet mechanism to achieve the kinetic gating required to sequester their macrocyclic substrates from bulk solution. Threading occurs as a result of active template reactions between the pump terminus amine and an acyl electrophile, whereby the bond-forming reaction is accelerated through the cavity of a crown ether. Carboxylation of the resulting amide results in displacement of the ring to the collection region of the thread. Conversion of the carbamate to a phenolic ester provides an intermediate rotaxane suitable for further pumping cycles. In this way rings can be ratcheted onto a thread from one or both ends of appropriately designed molecular pumps. Each pumping cycle results in one additional ring being added to the thread per terminus acyl group. The absence of pseudorotaxane states ensures that no dethreading of intermediates occurs during the pump operation. This facilitates the loading of different macrocycles in any chosen sequence, illustrated by the pump-mediated synthesis of a [4]rotaxane containing three different macrocycles as a single sequence isomer. A [5]rotaxane synthesized using a dual-opening transamidation pump was structurally characterized by single-crystal X-ray diffraction, revealing a series of stabilizing CH···O interactions between the crown ethers and the polyethylene glycol catchment region of the thread.

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“…A wealth of methodologies has now been elaborated to access mechanically interlocked species in high yields. 9 These can be broadly split into two categories: passive templates (PTs), which utilise non-covalent interactions such as hydrogen-bonding, 10 π–π interactions, 11 anion-binding, 12 radical-pairing 13 or coordination bonds 14 to pre-organise components, and active metal templates (AMTs), 15 wherein metal ion templates catalyse covalent bond formation to trap the mechanical bond.…”

Section: Introductionmentioning

confidence: 99%