Adaptation in Constitutional Dynamic Libraries and Networks, Switching between Orthogonal Metalloselection and Photoselection Processes

Vantomme, Ghislaine; Jiang, Shimei; Lehn, Jean Marie

doi:10.1021/ja504813r

Cited by 106 publications

(90 citation statements)

References 80 publications

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“…Origin of the enhanced reactivity of the macrocycles 1·N 2 O and 2·N 2 O 3 We showedp reviously [10] that steric strain caused by CH 3 /CH 3 interaction on introduction of methyl groups at the Ca nd N sites at the ends of the C=NÀN unit of the hydrazone C (Figure 1) caused am arked twist around the NÀNb ond, thus decreasing conjugation within the C=NÀN fragment and leading to as ignificant increase of the reactivity of the hydrazone bond. As ac onsequence, constitutionald ynamic exchange reactions werem arkedly facilitated.…”

Section: Macrocyclic Compounds Of Dialdehydementioning

confidence: 90%

“…Typical lone-pair/carbonyl conjugation (top) is prevented in the representative bridgeheadtwisted amides A [6] and B, [7] which present atypical reactivities. As train-activated hydrazone C [10] is also shown.…”

Section: Introductionmentioning

confidence: 98%

“…In the twisted amides A and B,i nw hich the amide group is located at ab ridgehead, such ideal electron delocalisation is Bredt's rule-forbidden, [9] strongly influencing their reactivity by decreasing their stability and inertness towards nucleophilic attack. [6][7][8] As an example of reactivity inducedb ys train duet os terically demanding groups, we have recently reported that the in-troduction of two methyl groups in the hydrazone C [10] markedly enhances its reactivity towards the dynamic covalent exchange of the hydrazine component as ar esult of the distortion from planarity of the C=NÀNÀMe group that decreases the conjugation between the nitrogen CÀNÀMe electronic lone pair and the C=Nd ouble bond. [11] Besides activation by such steric repulsion and by angular deformation,v ery significant strain may be generated by the overall electronic effects due to heteroatoms.…”

Section: Introductionmentioning

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: Macrocyclic Compounds Of Dialdehydementioning

confidence: 90%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

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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“…Thus, various solvents and bases were further tested in order to optimize the aromatization reaction (entries [5][6][7][8][9]. To our surprise, when 4ba was heated with a mixture of pyridine and an excess of concentrated hydrochloric acid in ethanol, it was quickly converted into another compound in high yield, which was carefully identified to be an aromatic pyrrole derivative 5ba (entry 4).…”

Section: Scheme 2 Formation Of 3 Andmentioning

confidence: 99%

Formation and aromatization of strained bicyclic pyrazolidines via tandem reaction of alkyl 2-aroyl-1-chlorocyclopropanecarboxylates with acylhydrazones

Huang

Gong

2015

Org. Biomol. Chem.

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A base-promoted reaction between alkyl 2-aroyl-1-chlorocyclopropanecarboxylates and acylhydrazones is described. In common solvents, the reactions proceed smoothly under mild conditions, providing mainly the formal substitution product , as well as a little amount of the formal [3 + 2] cycloaddition product . This strained bicyclic pyrazolidine , however, became the predominant product in DMSO. Moreover, a novel aromatization process of the fused pyrazolidine into 2,3,5-trisubstituted pyrrole has been successfully achieved in excellent yield via treatment with a HCl-pyridine system.

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“…In the last three years, hydrazones have experienced important application in various supramolecular chemistry areas as molecular switches (photochromism type T; until now only simple chromophoric systems such as benzene, naphthalene and indole were used), photo-and thermo-sensitive supramolecular arrangements and as colorimetric or fluorescent chemosensors [20,[44][45][46][47]. In the last three years, hydrazones have experienced important application in various supramolecular chemistry areas as molecular switches (photochromism type T; until now only simple chromophoric systems such as benzene, naphthalene and indole were used), photo-and thermo-sensitive supramolecular arrangements and as colorimetric or fluorescent chemosensors [20,[44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Isatin N²-diphenylhydrazones: new easily synthesized Vis-Vis molecular photoswitches

et al. 2015

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The photochromic properties of isatin N 2 -diphenylhydrazones as a new type of molecular switches were investigated. Interestingly, dimerization stabilizes the formation of only E-isomers in synthesis, even without Z-isomer presence in the mother liquor. The irradiation of E-isomers in solution at their absorption maxima leads to the formation of the corresponding Z-isomers. Although the shift in absorption maximum is not large and photochemical quantum yields are lower compared than in commonly used photoswitches, the absorbance changes are sufficient for potential practical use of these compounds as On-Off switches when the readout wavelength is optimally selected. The process is reversible and switching cycles can be repeated many times in both directions. Determined thermodynamic parameters and calculated geometry of the transition state clearly indicate the inverse mechanism of thermally initiated slow back Z-E isomerization. Due to the Vis-Vis character of molecular photoswitching and significant geometric changes during the switching process, isatin N 2 -diphenylhydrazones are eminently suitable for molecular switching in biological/biotechnological applications. Moreover, the interaction of isatin N 2 -diphenylhydrazones with strongly basic anions increases their functionality and creates a four-state On-Off switch in one molecule. This four-state switch includes the unique E-Z isomerization induced photochemical switching between two stable tautomeric forms of organic amide anion. Simple synthesis of these derivatives and their sufficiently sensitive response to external stimuli promote isatin N 2 -diphenylhydrazones as suitable candidates for both discussed photochemistry areas (molecular switching and actinometry).

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Adaptation in Constitutional Dynamic Libraries and Networks, Switching between Orthogonal Metalloselection and Photoselection Processes

Cited by 106 publications

References 80 publications

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

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

Formation and aromatization of strained bicyclic pyrazolidines via tandem reaction of alkyl 2-aroyl-1-chlorocyclopropanecarboxylates with acylhydrazones

Isatin N²-diphenylhydrazones: new easily synthesized Vis-Vis molecular photoswitches

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Adaptation in Constitutional Dynamic Libraries and Networks, Switching between Orthogonal Metalloselection and Photoselection Processes

Cited by 106 publications

References 80 publications

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

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

Formation and aromatization of strained bicyclic pyrazolidines via tandem reaction of alkyl 2-aroyl-1-chlorocyclopropanecarboxylates with acylhydrazones

Isatin N2-diphenylhydrazones: new easily synthesized Vis-Vis molecular photoswitches

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Product

Resources

About

Isatin N²-diphenylhydrazones: new easily synthesized Vis-Vis molecular photoswitches