Equilibrating Dynamic [2]Rotaxanes

Haussmann, Philip C.; Khan, Saeed I.; Stoddart, J. Fraser

doi:10.1021/jo0708590

Cited by 55 publications

(24 citation statements)

References 66 publications

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“…The solid-state structure fora na nalogous derivativeo ft he dialdehyde 2 also displays aWshape. [20] Reaction of dialdehyde 1w ith the diamine N 2 Oinp resence of cadmium ions-metal-templated formation of the macrocyclic complex Cd·(1·N 2 O).…”

Section: Resultsmentioning

confidence: 99%

“…9-10). [20] Reaction of dialdehyde 2w ith the diamine N 2 O 3 in presence of cadmium ions-metal-templated formation of the macrocyclic complex Cd·(2·N 2 O 3 ).…”

Section: Resultsmentioning

confidence: 99%

“…[19][20][21] and by determination of its solid-state molecular structure (see Supporting Information, p. 21). The solid-state structure shows that the Cd 2 + cation is bound to one counterion and two water molecules and not to the oxygen atoms of the diamine component, which is too distantf or ad irect coordination.I mine-protonCd 2 + -cation spin-spin splittings are observed in the 1 HNMR spectrum (Figure 4; top).…”

Section: Resultsmentioning

confidence: 99%

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Strain‐Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines

Ratjen

Vantomme

Lehn

2015

Chemistry A European J

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The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by (1) H NMR spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes.

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Section: Resultsmentioning

confidence: 99%

“…9-10). [20] Reaction of dialdehyde 2w ith the diamine N 2 O 3 in presence of cadmium ions-metal-templated formation of the macrocyclic complex Cd·(2·N 2 O 3 ).…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Strain‐Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines

Ratjen

Vantomme

Lehn

2015

Chemistry A European J

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“…In the two step condensation-reduction process, they obtained the desired [2]rotaxane in 70% yield after standard column chromatography. Stoddart et al used this strategy later on to assemble mechanically interlocked dendrimers [61], long rotaxaneoligomers [62] and to study the dynamics of reversible rotaxanes through imine bond formation [63].…”

Section: Rotaxane Formation Through Macrocycle Ring-closing Reactionsmentioning

confidence: 99%

Recent Advances in the Synthesis of Ammonium-Based Rotaxanes

Thibeault

Morin

2010

Molecules

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Abstract:The number of synthetic methods enabling the preparation of ammonium-based rotaxanes has increased very rapidly in the past ten years. The challenge in the synthesis of rotaxanes results from the rather weak interactions between the ammonium-containing rod and the crown ether macrocycle in the pseudorotaxane structure that rely mostly on O·H hydrogen bonds. Indeed, no strong base or polar solvent that could break up H-bonding can be used during the formation of rotaxanes because the two components will separate as two distinct entities. Moreover, most of the reactions have to be performed at room temperature to favor the formation of pseudorotaxane in solution. These non-trivial prerequisites have been taken into account to develop efficient reaction conditions for the preparation of rotaxanes and those are described in detail along this review.

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“…A DCL was created57 in our research laboratories by refluxing 2,2′‐oxybis(ethylamine) with 2,6‐diformylpyridine in toluene (Scheme ) under Dean–Stark conditions. Mass spectrometry revealed that the DCL contains at least nine members, one of which is a [24]crown‐8‐like macrocycle.…”

Section: Imine Bondsmentioning

confidence: 99%

Synthesizing interlocked molecules dynamically

Haussmann

Stoddart

2009

The Chemical Record

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As the complexity of mechanically interlocked molecular architectures increases, it is important to understand the underlying principles, such as molecular recognition and self-assembly processes, that govern the practice of template-directed synthesis necessary to create these particular compounds. In this review, we explain the importance of dynamic processes in the synthesis of mechanically interlocked compounds. We show how many different dynamic covalent bonds have been used in the synthesis of rotaxanes, catenanes, and other higher-order mechanically interlocked compounds, with the goal of revealing the state of the art in dynamic covalent chemistry.

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Equilibrating Dynamic [2]Rotaxanes

Cited by 55 publications

References 66 publications

Strain‐Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines

Strain‐Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines

Recent Advances in the Synthesis of Ammonium-Based Rotaxanes

Synthesizing interlocked molecules dynamically

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