Parahydrogen‐Based Hyperpolarization for Biomedicine

Hövener, Jan‐Bernd; Pravdivtsev, Andrey N.; Kidd, Bryce E.; Bowers, Clifford R.; Glöggler, Stefan; Kovtunov, Kirill V.; Plaumann, Markus; Katz‐Brull, Rachel; Buckenmaier, Kai; Jerschow, Alexej; Reineri, Francesca; Theis, Thomas; Shchepin, Roman V.; Wagner, Shawn; Bhattacharya, Pratip K.; Zacharias, Nikolaos; Chekmenev, Eduard Y.

doi:10.1002/anie.201711842

Cited by 276 publications

(516 citation statements)

References 267 publications

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“…Our analysis of the 1 Hspectra and 15 Nspectra of diazirines (4,5) and supporting Gaussian calculations revealed that the 2 J HH between the 1 Hs pin pairs in the methylene (CH 2 ) moieties are comparable to the 1 (4,5). Singlet order was created at B % 0.3 mT.T he spin system parameters for simulation are the same as shown in Figure 1.…”

Section: Angewandte Chemiesupporting

confidence: 55%

“…It is noteworthy that the presence of 1 Hi nt he diazirine moiety leaves 15 N T 1 relaxation almost unaffected when compared to previous studies. Consequently, 1 J NN is unobservable and the 15 N resonance is split by 2 J NH for diazirine (1) (doublet) and by 2 J NH and 3 J NH for diazirines (2) and (3) Figure S1 in Supporting Information for the expanded views of asymmetric peak pattern for diazirines (4,5)). Consequently, 1 J NN is unobservable and the 15 N resonance is split by 2 J NH for diazirine (1) (doublet) and by 2 J NH and 3 J NH for diazirines (2) and (3) Figure S1 in Supporting Information for the expanded views of asymmetric peak pattern for diazirines (4,5)).…”

Section: Resultsmentioning

confidence: 99%

“…[18][19][20][21][22][23][24][25] In this article,wefocus on terminal diazirines as SABRE targets.T he terminal diazirines depicted in Table 1w ere chosen to probe various molecular motifs.I nm olecule (1) at erminal diazirine moiety is directly attached to an aryl group with as imple structure and J-coupling network. [10] Diazirines (4,5) have as tereogenic center, which makes it possible to probe hyperpolarized long-lived singlet states and to permit transfer to 1 H. In the following,wewill demonstrate astrategy to store polarization in hyperpolarized 15 N 2 singlets and then convert the polarization from 15 Nsinglet order into 1 Hm agnetization for more sensitive detection. [10] Diazirines (4,5) have as tereogenic center, which makes it possible to probe hyperpolarized long-lived singlet states and to permit transfer to 1 H. In the following,wewill demonstrate astrategy to store polarization in hyperpolarized 15 N 2 singlets and then convert the polarization from 15 Nsinglet order into 1 Hm agnetization for more sensitive detection.…”

mentioning

confidence: 99%

“…Experimentalspectra of hyperpolarized15 Nmagnetization created using the SABRE-SHEATH method for diazirines(1)(2)(3)(4)(5) and Jcoupling analysis for diazirines (1-3) (a-c). d,e) Hyperpolarized 15 N spectra of diazirines(4,5) were simulated using the Spinach Matlab extension.F or diazirine(4),3 J NH = 0.96 Hz, 3 J N'H' = 1.01 Hz, 3 J N'H = 0.63 Hz, 3 J NH' = 0.65 Hz. Ford iazirine (5), 3 J NH = 3 J N'H' = 3 J N'H = 3 J NH' = 0.83Hz.…”

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confidence: 99%

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Terminal Diazirines Enable Reverse Polarization Transfer from ¹⁵N₂ Singlets

et al. 2019

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Diazirine moieties are chemically stable and have been incorporated into biomolecules without impediment of biological activity.T he 15 N 2 labeled diazirines are appealing motifs for hyperpolarization supporting relaxation protected states with long-lived lifetimes.The (-CH 15 N 2 )diazirine groups investigated here are analogues to methyl groups,w hich provides the opportunity to transfer polarization stored on arelaxation protected (-CH 15 N 2 )moiety to 1 H, thus combining the advantages of long lifetimes of 15 Np olarization with superior sensitivity of 1 Hdetection. Despite the proximity of 1 H to 15 Nnuclei in the diazirine moiety, 15 NT 1 times of up to (4.6 AE 0.4) min and singlet lifetimes T s of up to (17.5 AE 3.8) min are observed. Furthermore,w ef ound terminal diazirines to support hyperpolarized 1 H 2 singlet states in CH 2 groups of chiral molecules.T he singlet lifetime of 1 Hs inglets is up to (9.2 AE 1.8) min, thus exceeding 1 HT 1 relaxation time (at 8.45 T) by afactor of % 100.

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Section: Angewandte Chemiesupporting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Terminal Diazirines Enable Reverse Polarization Transfer from ¹⁵N₂ Singlets

et al. 2019

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“…[28] Other hyperpolarization methods are dissolution-DNP, a powerful tool to hyperpolarize small molecules in liquid solutions, [29,30] and DNP surface-enhanced NMR spectroscopy (DNP-SENS), which was used to study metalorganic frameworks and mesoporous materials. [37] With homogeneous catalysts, there is a general problem of catalyst separation from the hyperpolarized product, although they still can be used for the production of HP gases, [38,39] small molecules, [40,41] including bioactive ones, [42][43][44] and examination of reactive intermediates. [32] Taking into account mentioned constrains of the polarizable gases in SEOP and DNP methods, heterogeneous PHIP [33,34] (HET-PHIP) has emerged as an attractive alternative because of its simplicity and robustness for the production of hyperpolarized (HP) gases.…”

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confidence: 99%

Robust In Situ Magnetic Resonance Imaging of Heterogeneous Catalytic Hydrogenation with and without Hyperpolarization

Kovtunov

Lebedev²,

Svyatova

et al. 2019

ChemCatChem

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Magnetic resonance imaging (MRI) is a powerful technique to characterize reactors during operating catalytic processes. However, MRI studies of heterogeneous catalytic reactions are particularly challenging because the low spin density of reacting and product fluids (for gas phase reactions) as well as magnetic field inhomogeneity, caused by the presence of a solid catalyst inside a reactor, exacerbate already low intrinsic sensitivity of this method. While hyperpolarization techniques such as parahydrogen induced polarization (PHIP) can substantially increase the NMR signal intensity, this general strategy to enable MR imaging of working heterogeneous catalysts to date remains underexplored. Here, we present a new type of model catalytic reactors for MRI that allow the characterization of a heterogeneous hydrogenation reaction aided by the PHIP signal enhancement, but also suitable for the imaging of regular nonpolarized gases. These catalytic systems permit exploring the complex interplay between chemistry and fluid-dynamics that are typically encountered in practical systems, but mostly absent in simple batch reactors. High stability of the model reactors at catalytic conditions and their fabrication simplicity make this approach compelling for in situ studies of heterogeneous catalytic processes by MRI.Catalytic processes (e. g., hydrogenation, reforming, oxidation, etc.) are at the cornerstone of chemical and petrochemical industry [1] and, to make these processes more sustainable, control over reaction selectivity, conversion rates, mass and heat transport inside the working reactor (that is under operando conditions) is required. Magnetic resonance imaging (MRI) is a tool applicable to operando studies that provide information for example about the distribution of liquids in the catalyst pellet during hydrogenation of α-methylstyrene [2] or heptene, [3] the coke profiles within a catalyst pellet, [4] the flow of water [5] or propane [6] through a packed bed, the structure of a porous medium and the water flow during the deposition of fines, [7] or the velocities of particles in a fluidized bed. [8][9][10] MRI of reactors utilizing gases are not as developed as studies of liquids because the spin density in the gas phase is ca. 3 orders of magnitude lower relative to the condensed phase, which significantly limits the deployment of MRI for studying gases. [11] Nevertheless, a recent report showed that the distribution of the reactants and products inside a monolith type reactor can be measured even in the gas phase during ethylene hydrogenation reaction using two different catalyst supports, thereby revealing an effect of the support on the mass and heat transport. [12] Overall, to date, there are only a handful of MRI studies of the gas phase reactions with regular non-hyperpolarized gases. [13,14] The limitation of low NMR sensitivity spurs the implementation of hyperpolarization techniques, which can potentially increase the intensity of NMR signals by up to several orders of magnitude, including spin-ex...

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