Reversible guest exchange mechanisms in supramolecular host–guest assemblies

Pluth, Michael D.; Raymond, Kenneth N.

doi:10.1039/b603168b

Cited by 459 publications

(238 citation statements)

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“…[1][2][3][4][5][6] These materials have been studied, for example, from the perspective of exploring the self-assembly of such compounds, 2 to develop receptors, 3,5 to stabilise reactive intermediates or products, and for investigating catalysis within the closed environment of the polyhedral assemblies. 3,4,6 A related field on the study of anion binding has undergone a similar, rapid development.…”

Section: Introductionmentioning

confidence: 99%

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Kadir

Clements

Hanton

et al. 2012

Supramolecular Chemistry

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Pre-organisation or a hydrogen bonding mismatch; silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies, Supramolecular Chemistry, 2012; 24(8) Retained rights the right to post on a non-commercial basis your "Author's Accepted Manuscript" (i.e., your manuscript in the form accepted for publication, revised after peer review; formerly a "postprint"), as a digital file on your own website for personal or professional use, or on your institution's network or intranet or website, or in a subject repository that does not offer content for commercial sale or for any systematic external distribution by a third party, provided that you do not use the PDF version of the article prepared by us and that you include any amendments or deletions or warnings relating to the article issued or published by us; in compliance with the embargo periods detailed below; and only with this acknowledgement:

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Section: Introductionmentioning

confidence: 99%

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Kadir

Clements

Hanton

et al. 2012

Supramolecular Chemistry

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“…While the development of synthetic host-guest systems has not reached the level of enzyme specificity, the characteristics of each synthetic assembly, such as the size, shape, charge, and functional group availability, greatly influence the guest-binding characteristics and have led to remarkable and often unexpected reactivity. 9,[16][17][18][19][20][21][22][23] For example, the increased local concentration upon encapsulation of substrates for bimolecular reactions has been exploited for enhanced reactivity inside of synthetic hosts. By pre-organizing substrates, supramolecular assemblies are able to catalyze cycloadditions or pericyclic reactions such as Diels-Alder reactions.…”

Section: Introductionmentioning

confidence: 99%

Spin Equilibria in Monomeric Manganocenes: Solid-State Magnetic and EXAFS Studies

et al. 2009

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A water-soluble self-assembled supramolecular host molecule catalyzes the hydrolysis of orthoformates in basic solution. Comparison of the rate constants of the catalyzed and uncatalyzed reactions for hydrolysis displays rate accelerations of up to 3900 for tri-n-propyl orthoformate. Kinetic analysis shows that the mechanism of hydrolysis with the supramolecular host obeys the Michaelis-Menten model.Mechanistic studies, including 13 C-labeling experiments, revealed that the resting state of the catalytic system is the neutral substrate encapsulated in the host. Activation parameters for the k cat step of the reaction revealed that upon encapsulation in the assembly, the entropy of activation becomes more negative in contrast to the uncatalyzed reaction. Furthermore, solvent isotope effects reveal a normal k(H 2 O)/k(D 2 O) = 1.6, confirming that proton transfer is occurring in the transition state and is rate limiting in the catalyzed reaction. In comparison to the uncatalyzed reaction, which operates by an A-1 mechanism in which the decomposition of the protonated substrate is rate limiting, the encapsulated reaction proceeds through an A-S E 2 mechanism in which proton transfer from protonated water to the substrate is rate limiting.

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“…[2][3][4][5][6] While the interaction between host and guest molecules is generally the focus of mechanistic studies of host-guest complexes, the interaction of the host-guest complex with other species in solution remains largely unknown, although in principle accessible by diffusion studies. Several NMR techniques are available to monitor diffusion and have recently been reviewed.…”

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confidence: 99%

Diffusion of a Highly Charged Supramolecular Assembly: Direct Observation of Ion Association in Water¹

et al. 2008

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Understanding the solution behavior of supramolecular assemblies is essential for a full understanding of the formation and chemistry of synthetic host-guest systems. [2][3][4][5][6] While the interaction between host and guest molecules is generally the focus of mechanistic studies of host-guest complexes, the interaction of the host-guest complex with other species in solution remains largely unknown, although in principle accessible by diffusion studies. Several NMR techniques are available to monitor diffusion and have recently been reviewed. [7][8][9] Pulsed gradient spin-echo (PGSE) NMR methods have attracted increasing interest, since they allow diffusion coefficients to be measured with high accuracy; they have been successfully used with observation of 7 Li and 31 P nuclei as well as with 1 H NMR. 10,11 We report here the direct measurement of diffusion coefficients to observe ion-association interactions by counter cations with a highly-charged supramolecular assembly.Raymond and coworkers have described the design and chemistry of a class of metal-ligand supramolecular assemblies over the past decade.12-15 The [Ga 4 L 6 ] 12-(L = 1,5-bis(2,3-dihydroxybenzamido)naphthalene) (1) (Figure 1) assembly has garnered the most attention, with the exploration of the dynamics and mechanism of guest exchange as well as the ability of 1 to achieve either stoichiometric or catalytic reactions inside its interior cavity. [16][17][18][19] Recent studies have revealed the importance of counter cations in solution on the chemistry of 1. During the mechanistic study of the C-H bond activation of aldehydes by [Cp * Ir(PMe 3 )(olefin)11-a stepwise guest dissociation mechanism with an ion-paired intermediate was proposed.19 Similarly, in the mechanism for the hydrolysis of iminium cations generated from the 3-aza Cope rearrangement of enammonium cations in 1, the presence of an exterior ion association was part of the kinetic model. 17 To further substantiate the indirect kinetic evidence for such ion-paired species, we sought to explore the solution behavior of 1 by studying the diffusion of 1 with varying alkali and tetraalkyl ammonium cations. For large molecules in solution, such as synthetic supramolecular assemblies, the diffusion behavior of host and guest molecules can provide valuable information on host-guest interaction. One characteristic feature of a stable host-guest complex is that the host and guest molecules diffuse at the same rate in solution; this has been observed in a number of supramolecular systems. [20][21][22][23][24][25][26] In order to confirm that this system was suitable for study by diffusion NMR spectroscopy, a PGSE-DOSY spectrum was acquired of [NEt 4 ⊂ 1] 11- (Figure 2), which shows that the host and guest molecules diffuse at the same rate. Quantitative analysis of the data, from monitoring the integral of host and guest resonances as a function of applied gradient strength, gave identical diffusion coefficients, confirming that the host and guest molecules diffuse together.

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Reversible guest exchange mechanisms in supramolecular host–guest assemblies

Cited by 459 publications

References 36 publications

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Spin Equilibria in Monomeric Manganocenes: Solid-State Magnetic and EXAFS Studies

Diffusion of a Highly Charged Supramolecular Assembly: Direct Observation of Ion Association in Water¹

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Reversible guest exchange mechanisms in supramolecular host–guest assemblies

Cited by 459 publications

References 36 publications

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Pre-organisation or a hydrogen bonding mismatch: silver(I) diamide ligand coordination polymers versus discrete metallo-macrocyclic assemblies

Spin Equilibria in Monomeric Manganocenes: Solid-State Magnetic and EXAFS Studies

Diffusion of a Highly Charged Supramolecular Assembly: Direct Observation of Ion Association in Water1

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Diffusion of a Highly Charged Supramolecular Assembly: Direct Observation of Ion Association in Water¹