Diels–Alder Reactions of Inert Aromatic Compounds within a Self‐Assembled Coordination Cage

Horiuchi, Shigeo; Murase, Takashi; Fujita, Makoto

doi:10.1002/asia.201000842

Cited by 68 publications

(33 citation statements)

References 84 publications

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“…This loss of symmetry occurs because each guest occupies one half of the capsule. The guests are closely packed against the triazine panel and on the NMR timescale the cage loses its T d symmetry (see Supporting Information S4). For the empty cage, all pyridine rings are equivalent so that only two signals are observed for the pyridine protons.…”

Section: Resultsmentioning

confidence: 99%

Selective Co‐Encapsulation Inside an M₆L₄ Cage

Leenders

Becker

Kumpulainen

et al. 2016

Chemistry A European J

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There is broad interest in molecular encapsulation as such systems can be utilized to stabilize guests, facilitate reactions inside a cavity, or give rise to energy‐transfer processes in a confined space. Detailed understanding of encapsulation events is required to facilitate functional molecular encapsulation. In this contribution, it is demonstrated that Ir and Rh‐Cp‐type metal complexes can be encapsulated inside a self‐assembled M6L4 metallocage only in the presence of an aromatic compound as a second guest. The individual guests are not encapsulated, suggesting that only the pair of guests can fill the void of the cage. Hence, selective co‐encapsulation is observed. This principle is demonstrated by co‐encapsulation of a variety of combinations of metal complexes and aromatic guests, leading to several ternary complexes. These experiments demonstrate that the efficiency of formation of the ternary complexes depends on the individual components. Moreover, selective exchange of the components is possible, leading to formation of the most favorable complex. Besides the obvious size effect, a charge‐transfer interaction may also contribute to this effect. Charge‐transfer bands are clearly observed by UV/Vis spectrophotometry. A change in the oxidation potential of the encapsulated electron donor also leads to a shift in the charge‐transfer energy bands. As expected, metal complexes with a higher oxidation potential give rise to a higher charge‐transfer energy and a larger hypsochromic shift in the UV/Vis spectrum. These subtle energy differences may potentially be used to control the binding and reactivity of the complexes bound in a confined space.

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Section: Resultsmentioning

confidence: 99%

Selective Co‐Encapsulation Inside an M₆L₄ Cage

Leenders

Becker

Kumpulainen

et al. 2016

Chemistry A European J

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“…Other potential positive cage effects include i) higher stability of encapsulated catalysts vs. species in bulk solvent and ii) enhanced reaction rates due to local environment effects and substrate preorganization. [13][14][15][16][17][18][19][20][21] Cage catalysis is now rapidly developing and many examples spanning a wide variety of catalytic transformations can be found in literature. [6][7][8] Chief among these are palladium catalyzed reactions, hydrolysis reactions, SN2 reactions, rearrangement reactions and photochemical reactions.…”

Section: Introductionmentioning

confidence: 99%

How to Control the Rate of Heterogeneous Electron Transfer across the Rim of M₆L₁₂ and M₁₂L₂₄ Nanospheres

et al. 2020

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Catalysis in confined spaces, such as provided by supramolecular cages, is quickly gaining momentum. It allows for second coordination sphere strategies to control the selectivity and activity of transition metal catalysts, beyond the classical methods like fine-tuning the steric and electronic properties of the coordinating ligands. Only a few electrocatalytic reactions within cages have been reported, and there is no information regarding the electron transfer kinetics and thermodynamics of redox-active species encapsulated into supramolecular assemblies. This contribution revolves around the preparation of M6L12 and larger M12L24 (M= Pd or Pt) nanospheres functionalized with different numbers of redox-active probes encapsulated within their cavity, either in a covalent fashion via different types of linkers (flexible, rigid and conjugated or rigid and non-conjugated) or by supramolecular hydrogen bonding interactions. The redox-probes can be addressed by electrochemical electron transfer across the rim of nanospheres and the thermodynamics and kinetics of this process are described. Our study identifies that the linker type and the number of redox probes within the cage are useful handles to fine-tune the electron transfer rates, paving the way for the encapsulation of electro-active catalysts and electrocatalytic applications of such supramolecular assemblies.

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“…In the presence of such hosts, selectivity, rate acceleration, and even catalysis have been observed for a wide range of chemical transformations not readily attained in solution. Examples include cyclizations, Diels–Alder reactions, C−X activation, rearrangements, cycloadditions, olefin oxidation and metathesis, ring opening, condensation, hydrolysis, and hydration . In short, confinement controls reactivity.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Reaction of Carboxylic Acids and Isonitriles in a Self‐Assembled Capsule

Daver

Rebek

Himo

2020

Chemistry A European J

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Quantum chemical calculations were used to study the reaction of carboxylic acids with isonitriles inside a resorcinarene‐based self‐assembled capsule. Experimentally, it has been shown that the reactions between p‐tolylacetic acid and n‐butyl isonitrile or isopropyl isonitrile behave differently in the presence of the capsule compared both with each other and also with their solution counterparts. Herein, the reasons for these divergent behaviors are addressed by comparing the detailed energy profiles for the reactions of the two isonitriles inside and outside the capsule. An energy decomposition analysis was conducted to quantify the different factors affecting the reactivity. The calculations reproduce the experimental findings very well. Thus, encapsulation leads to lowering of the energy barrier for the first step of the reaction, the concerted α‐addition and proton transfer, which in solution is rate‐determining, and this explains the rate acceleration observed in the presence of the capsule. The barrier for the final step of the reaction, the 1,3 O→N acyl transfer, is calculated to be higher with the isopropyl substituent inside the capsule compared with n‐butyl. With the isopropyl substituent, the transition state and the product of this step are significantly shorter than the preceding intermediate, and this results in energetically unfavorable empty spaces inside the capsule, which cause a higher barrier. With the n‐butyl substituent, on the other hand, the carbon chain can untwine and hence uphold an appropriate guest length.

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Diels–Alder Reactions of Inert Aromatic Compounds within a Self‐Assembled Coordination Cage

Cited by 68 publications

References 84 publications

Selective Co‐Encapsulation Inside an M₆L₄ Cage

Selective Co‐Encapsulation Inside an M₆L₄ Cage

How to Control the Rate of Heterogeneous Electron Transfer across the Rim of M₆L₁₂ and M₁₂L₂₄ Nanospheres

Modeling the Reaction of Carboxylic Acids and Isonitriles in a Self‐Assembled Capsule

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Diels–Alder Reactions of Inert Aromatic Compounds within a Self‐Assembled Coordination Cage

Cited by 68 publications

References 84 publications

Selective Co‐Encapsulation Inside an M6L4 Cage

Selective Co‐Encapsulation Inside an M6L4 Cage

How to Control the Rate of Heterogeneous Electron Transfer across the Rim of M6L12 and M12L24 Nanospheres

Modeling the Reaction of Carboxylic Acids and Isonitriles in a Self‐Assembled Capsule

Contact Info

Product

Resources

About

Selective Co‐Encapsulation Inside an M₆L₄ Cage

Selective Co‐Encapsulation Inside an M₆L₄ Cage

How to Control the Rate of Heterogeneous Electron Transfer across the Rim of M₆L₁₂ and M₁₂L₂₄ Nanospheres