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Figure S13. Electrospray ionization mass spectra (ESI-MS) of a) the fraction 2 collected from the GPC and b) the pure contracted rotaxane 6 obtained after silica gel chromatography. The triangle and the diamond denote an artefact of the mass spectrometer and an undetermined m/z value of [6 + 28], respectively.
Source publication
The wrapping of an aromatic oligoamide helix around an active ester-containing [2]rotaxane enforced the sliding and the sequestration of the surrounding macrocycle around a part of the axle for which...
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Citations
... [2]rotaxane. [22] The foldamer-based molecular translocator 31 bears a carbamate cleft and an amide cleft as the different ends of its structure (Scheme 5a). This synthetic strategy started with the carbamoylation of the previously synthesized [2]rotaxane 32, in which a crown ether macrocycle binds to an alkylbenzylammonium station, giving intertwined compound 33 as the product (Scheme 5b). ...
... (b) Synthesis of 'impossible' [2]rotaxane 36 by using a foldamer transporter. [22] aminolysis reaction of these prerotaxanes 37 using n-propylamine (39) yielded the target interlocked compounds 38 in moderate yields (up to 21 %). ...
Impossible' rotaxanes, which are constituted by interlocked components without obvious binding motifs, have attracted the interest of the mechanically interlocked molecules (MIMs) community. Within the synthetic efforts reported in the last decades towards the preparation of MIMs, some innovative protocols for accessing 'impossible' rotaxanes have been developed. This short review highlights different selected synthetic examples of 'impossible' rotaxanes, as well as suggests some future directions of this research area.
Artificial molecular muscles are highly attractive in the field of molecular machinery due to their unique properties of contraction and stretching motion. However, the synthesis of molecular muscles poses formidable challenges as it is hindered by undesirable yields and poor selectivity. Herein, we present a procedure for the dynamic assembly of foldaxane‐based [ c 2]daisy chains, wherein the hermaphroditic sequences consisting of aromatic helices and peptide rods are interlocked through inter‐strand hydrogen‐bonding interactions. The binding complementarity facilitates a selective and efficient assembly of [ c 2]daisy chain structures, inhibiting the creation of by‐products. Introducing multiple recognition sites confers the system with contraction and stretching motion actuated by chemical stimuli. The rate of this muscle‐like motion is calculated to be 0.8 s ⁻¹ , which is 10 ⁷ times faster than that of complex dissociation.
"Improbable" rotaxanes consisting of interlocked conjugated components represent non‐trivial synthetic targets, not to mention those with all‐benzene scaffolds. Herein, a modular synthetic strategy has been established using an isolable azo‐linked pre‐rotaxane as the core module, in which the azo group functions as a tracelessly removable template to direct mechanical bond formations. Through versatile connections of the pre‐rotaxane and other customizable modules, [2]‐ and [3]rotaxanes derived from all‐benzene scaffolds have been accomplished, demonstrating the utility and potential of the synthetic design for all‐benzene interlocked supramolecules.
"Improbable" rotaxanes consisting of interlocked conjugated components represent non‐trivial synthetic targets, not to mention those with all‐benzene scaffolds. Herein, a modular synthetic strategy has been established using an isolable azo‐linked pre‐rotaxane as the core module, in which the azo group functions as a tracelessly removable template to direct mechanical bond formations. Through versatile connections of the pre‐rotaxane and other customizable modules, [2]‐ and [3]rotaxanes derived from all‐benzene scaffolds have been accomplished, demonstrating the utility and potential of the synthetic design for all‐benzene interlocked supramolecules.
Artificial molecular muscles are highly attractive in the field of molecular machinery due to their unique properties of contraction and stretching motion. However, the synthesis of molecular muscles poses formidable challenges as it is hindered by undesirable yields and poor selectivity. Herein, we present a procedure for the dynamic assembly of foldaxane‐based [c2]daisy chains, wherein the hermaphroditic sequences consisting of aromatic helices and peptide rods are interlocked through inter‐strand hydrogen‐bonding interactions. The binding complementarity facilitates a selective and efficient assembly of [c2]daisy chain structures, inhibiting the creation of by‐products. Introducing multiple recognition sites confers the system with contraction and stretching motion actuated by chemical stimuli. The rate of this muscle‐like motion is calculated to be 0.8 s⁻¹, which is 10⁷ times faster than that of complex dissociation.
We have developed a new approach for the synthesis of “improbable” rotaxanes by using malonate‐centered rotaxanes as interlocked surrogate precursors. Here, the desired dumbbell‐shaped structure can be assembled from two different, completely separate, portions, with the only residual structure introduced from the malonate surrogate being a methylene group. We have synthesized improbable [2]‐ and [3]rotaxanes with all‐hydrocarbon dumbbell‐shaped components to demonstrate the potential structural flexibility and scope of the guest species that can be interlocked when using this approach.
We have developed a new approach for the synthesis of “improbable” rotaxanes by using malonate‐centered rotaxanes as interlocked surrogate precursors. Here, the desired dumbbell‐shaped structure can be assembled from two different, completely separate, portions, with the only residual structure introduced from the malonate surrogate being a methylene group. We have synthesized improbable [2]‐ and [3]rotaxanes with all‐hydrocarbon dumbbell‐shaped components to demonstrate the potential structural flexibility and scope of the guest species that can be interlocked when using this approach.
Here is reported the synthesis and characterization of an interlocked figure‐of‐eight rotaxane molecular shuttle from a dibenzo‐24‐crown‐8 (DB24C8) derivative. This latter bears two molecular chains, whose extremities are able to react together by click chemistry. One of the two substituting chain holds an ammonium function aimed at driving the self‐entanglement through the complexation of the DB24C8 moiety. In the targeted figure‐of‐eight rotaxane, shuttling of the DB24C8 along the threaded axle from the best ammonium station to the weaker binding site triazolium was performed through deprotonation‐then‐carbamoylation of the ammonium. This way, two discrete co‐conformational states were obtained, in which the folding and size of the two loops could be changed.
Here is reported the synthesis and characterization of an interlocked figure‐of‐eight rotaxane molecular shuttle from a dibenzo‐24‐crown‐8 (DB24C8) derivative. This latter bears two molecular chains, whose extremities are able to react together by click chemistry. One of the two substituting chain holds an ammonium function aimed at driving the self‐entanglement through the complexation of the DB24C8 moiety. In the targeted figure‐of‐eight rotaxane, shuttling of the DB24C8 along the threaded axle from the best ammonium station to the weaker binding site triazolium was performed through deprotonation or deprotonation‐then‐carbamoylation of the ammonium. This way, two discrete co‐conformational states were obtained, in which the folding and size of the two loops could be changed.
