The Fundamentals of Making Mechanical Bonds

doi:10.1002/9781119044123.ch2

Cited by 4 publications

(1 citation statement)

References 1,444 publications

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“…Rotaxanes are prototypical synthetic molecular machines consisting of a macrocycle threaded onto an axle . They enable controlled large-amplitude movement and positioning of one mechanically interlocked component with respect to another. − Translocation of the ring can be triggered by a stimulus, resulting in its directional displacement along the thread.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Fluctuations in Single-Molecule Rotaxane Experiments Reveal an Intermediate Weak Binding State during Shuttling

et al. 2021

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We report on the use of atomic force microscopy (AFM) to identify and characterize an intermediate state in macrocycle shuttling in a hydrogen bonded amide-based molecular shuttle. The [2]rotaxane consists of a benzylic amide macrocycle mechanically locked onto a thread that bears both fumaramide and succinic amide-ester sites, each of which can bind to the macrocycle through up to four intercomponent hydrogen bonds. Using AFM-based single-molecule force spectroscopy, we mechanically triggered the translocation of the ring between the two principal binding sites ("stations") on the axle. Equilibrium fluctuations reveal another interacting site involving the two oxygen atoms in the middle of the thread. We characterized the ring occupancy distribution over time, which confirms the intermediate in both shuttling directions. The study provides evidence of weak hydrogen bonds that are difficult to detect using other methods and shows how the composition of the thread can significantly influence the shuttling dynamics by slowing down the ring motion between the principal binding sites. More generally, the study illustrates the utility that single-molecule experiments, such as force spectroscopy, can offer for elucidating the structure and dynamics of synthetic molecular machines.

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Section: Introductionmentioning

confidence: 99%

Real-Time Fluctuations in Single-Molecule Rotaxane Experiments Reveal an Intermediate Weak Binding State during Shuttling

et al. 2021

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[2]Rotaxane End‐Capping Synthesis by Click Michael‐Type Addition to the Vinyl Sulfonyl Group

David

García‐Cerezo

Campaña

et al. 2019

Chemistry A European J

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We report the application of the click Michael-type additionr eactiont ov inyl sulfone or vinyl sulfonate groups in the synthesis of rotaxanes through the threading-and-capping method. This methodology has proven to be efficient and versatile as it allowed the preparation of rotaxanes using template approaches based on different noncovalent interactions (i.e.,d onor-acceptor p-p interactions or hydrogen bonding) in yieldso fg enerally 60-80 %a nd up to 91 % aided by the mild conditions required (room temperature or 0 8Ca nd am ild base such as Et 3 No r4 -(N,N-dimethylamino)pyridine (DMAP)). Furthermore, the use of vinyl sulfonate moieties, whicha re suitable motifs for coupling-and-decoupling (CAD) chemistry,i mpliesa nother advantage because it allowst he controlled chemical disassembly of the rotaxanes into their components through nucleophilic substitution of the sulfonatesr esultingf rom the capping step with at hiol underm ildconditions (Cs 2 CO 3 and room temperature).

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A [2]Rotaxane-Based Circularly Polarized Luminescence Switch

et al. 2019

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A rotaxane-based molecular shuttle has been synthesized in which the switching of the position of a fluorescent macrocycle on the thread turns “on” or “off” the circularly polarized luminescence (CPL) of the system while maintaining similar fluorescence profiles and quantum yields in both states. The chiroptical activity relies on the chiral information transfer from an ammonium salt incorporating d - or l -phenylalanine residues as chiral stereogenic covalent units to an otherwise achiral crown ether macrocycle bearing a luminescent 2,2′-bipyrene unit when they interact through hydrogen bonding. Each enantiomeric thread induces CPL responses of opposite signs on the macrocycle. Upon addition of base, the switching of the position of the macrocycle to a triazolium group disables the chiral information transfer to the macrocycle, switching “off” the CPL response. The in situ switching upon several acid/base cycles is also demonstrated.

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The Fundamentals of Making Mechanical Bonds

Cited by 4 publications

References 1,444 publications

Real-Time Fluctuations in Single-Molecule Rotaxane Experiments Reveal an Intermediate Weak Binding State during Shuttling

Real-Time Fluctuations in Single-Molecule Rotaxane Experiments Reveal an Intermediate Weak Binding State during Shuttling

[2]Rotaxane End‐Capping Synthesis by Click Michael‐Type Addition to the Vinyl Sulfonyl Group

A [2]Rotaxane-Based Circularly Polarized Luminescence Switch

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