Xe affinities of water-soluble cryptophanes and the role of confined water

Gao, Lu; Liu, Wenhao; Lee, One Sun; Dmochowski, Ivan J.; Saven, Jeffery G.

doi:10.1039/c5sc02401c

Cited by 23 publications

(49 citation statements)

References 59 publications

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“…This assertion is based on the results from density functional theory (DFT), molecular dynamics (MD), 11,23 and NMR experiments. Although as many as 332 conformations are thermally accessible by single cyanostars, the Boltzmann-weighted variation in atomic positions relative to the most stable conformer leads to ~87% retention of the molecule’s size, 24 indicative of high shape persistence.…”

Section: Introductionmentioning

confidence: 99%

Flexibility Coexists with Shape-Persistence in Cyanostar Macrocycles

et al. 2016

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Shape-persistent macrocycles are attractive functional targets for synthesis, molecular recognition, and hierarchical self-assembly. Such macrocycles are non-collapsible and geometrically well-defined, and they are traditionally characterized by having repeat units and low conformational flexibility. Here, we find it necessary to refine these ideas in the face of a highly flexible yet shape-persistent macrocycles. A molecule is shape-persistent if it has a small change in shape when perturbed by external stimuli (e.g., heat, light, and redox chemistry). In support of this idea we provide the first examination of the relationships between a macrocycle’s shape persistence, its conformational space, and the resulting functions. We do this with a star-shaped macrocycle called cyanostar that is flexible as well as being shape-persistent. We employed molecular dynamics (MD), density functional theory (DFT), and NMR experiments. Considering a thermal bath as a stimulus we found a single macrocycle has 332 accessible conformers with olefins undergoing rapid interconversion by up-down and in-out motions on short time scales (0.2 ns). These many interconverting conformations classify single cyanostars as flexible. To determine and confirm that cyanostars are shape-persistent, we show that it has a high 87% shape similarity across these conformations. To further test the idea, we use the binding of diglyme to the single macrocycle as guest-induced stimulation. This guest has almost no effect on the conformational space. However, formation of a 2:1 sandwich complex involving two macrocycles enhances rigidity and dramatically shifts the conformer distribution towards perfect bowls. Overall, the present study expands the scope of shape-persistent macrocycles to include flexible macrocycles if and only if their conformers have similar shapes.

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Section: Introductionmentioning

confidence: 99%

Flexibility Coexists with Shape-Persistence in Cyanostar Macrocycles

et al. 2016

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“…It is obvious that the cage size impacts the binding constant as illustrated in a comparative review, [129] but substitutions on CrA and cryptophane-111 can also increase the affinity. [130] Understanding the details behind the complexation of Xe revealed induced fit properties [131] and displacement of water [132] as contributing forces. The linker length between cage and targeting unit is a critical parameter for enabling the right balance between sufficient mobility required for narrow resonances and desired surface contact with the target to shift the signal.…”

Section: 129xe Cages and Hyper-cest Mrimentioning

confidence: 99%

“…While many cages were first characterized in organic solvents, various synthesis studies succeeded to improve solubility. [130c, 132, 134] …”

Section: 129xe Cages and Hyper-cest Mrimentioning

confidence: 99%

NMR Hyperpolarization Techniques of Gases

Barskiy

Coffey

Nikolaou

et al. 2016

Chemistry A European J

157

117

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Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4–8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can be more readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This mini-review covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science.

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“…Although the vast majority of SEOP experiments have employed the spin I=1/2 noble gas isotopes 129 Xe and 3 He, the quadrupolar species 21 Ne (I=3/2), [36] 83 Kr (I=9/2), [37] and 131 Xe [38] (I=3/2) can also be polarized via this method. For the alkali metal vapor, Rb is most-commonly employed for practical reasons-including its low melting point [39] (facilitating vaporization) and the availability of high-powered lasers resonant with its D1 transition [40] ; however, K and Cs are also utilized (particularly for 3 He [41] and 129 Xe, [42] respectively).…”

Section: Seopmentioning

confidence: 99%

“…It is obvious that the cage size impacts the binding constant as illustrated in a comparative review, [128] but substitutions on CrA and cryptophane-111 can also increase the affinity. [129] Understanding the details behind the complexation of Xe revealed induced fit properties [130] and displacement of water [131] as contributing forces. The linker length between cage and targeting unit is a critical parameter for enabling the right balance between sufficient mobility required for narrow resonances and desired surface contact with the target to shift the signal.…”

Section: Xenon Biosensor Conceptmentioning

confidence: 99%

NMR Hyperpolarization Techniques of Gases

Barskiy

Coffey

Nikolaou

et al. 2016

Chemistry A European J

View full text Add to dashboard Cite

Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4-8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can be more readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This mini-review covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science.

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Xe affinities of water-soluble cryptophanes and the role of confined water

Abstract: Simulations provide molecular insight on the aqueous binding of Xe to cryptophanes.

Cited by 23 publications

References 59 publications

Flexibility Coexists with Shape-Persistence in Cyanostar Macrocycles

Flexibility Coexists with Shape-Persistence in Cyanostar Macrocycles

NMR Hyperpolarization Techniques of Gases

NMR Hyperpolarization Techniques of Gases

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