Parahydrogen discriminated PHIP at low magnetic fields

Prina, I.; Buljubasich, L.; Acosta, Rodolfo H.

doi:10.1016/j.jmr.2014.11.010

Cited by 10 publications

(4 citation statements)

References 36 publications

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“…As a result, the direct detection of PHIP products suffers from massive (more than 2 orders of magnitude) signal cancellation. 37−39 …”

Section: Introductionmentioning

confidence: 99%

“…In practice, this results in the collapse of the NMR lines because the difference in the chemical shift of the two nascent protons is too small with respect to the spin–spin coupling ( J HH ) and also with respect to the magnetic field homogeneity. As a result, the direct detection of PHIP products suffers from massive (more than 2 orders of magnitude) signal cancellation. − …”

Section: Introductionmentioning

confidence: 99%

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NMR SLIC Sensing of Hydrogenation Reactions Using Parahydrogen in Low Magnetic Fields

et al. 2016

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Parahydrogen-induced polarization (PHIP) is an NMR hyperpolarization technique that increases nuclear spin polarization by orders of magnitude, and it is particularly well-suited to study hydrogenation reactions. However, the use of high-field NMR spectroscopy is not always possible, especially in the context of potential industrial-scale reactor applications. On the other hand, the direct low-field NMR detection of reaction products with enhanced nuclear spin polarization is challenging due to near complete signal cancellation from nascent parahydrogen protons. We show that hydrogenation products prepared by PHIP can be irradiated with weak (on the order of spin–spin couplings of a few hertz) alternating magnetic field (called Spin-Lock Induced Crossing or SLIC) and consequently efficiently detected at low magnetic field (e.g., 0.05 T used here) using examples of several types of organic molecules containing a vinyl moiety. The detected hyperpolarized signals from several reaction products at tens of millimolar concentrations were enhanced by 10000-fold, producing NMR signals an order of magnitude greater than the background signal from protonated solvents.

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“…As a result, the direct detection of PHIP products suffers from massive (more than 2 orders of magnitude) signal cancellation. 37−39 …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

NMR SLIC Sensing of Hydrogenation Reactions Using Parahydrogen in Low Magnetic Fields

et al. 2016

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“…[21] To determine whether the separation among PHIP and thermal contributions at a low field still occurs, numerical simulations were performed on simplified spin systems, at 20 MHz proton Larmor frequency. [31] The calculated spectra for two and three spin systems display separated contributions in the centre and the borders of the spectral window, as for the high field case. However, in this situation, PHIP signals originated in higher spins order after the reaction appears at the border, interfering with thermal signals.…”

Section: Phd-phip At Low Fieldmentioning

confidence: 76%

“…The theoretical predictions were confirmed experimentally at 0.45 Tesla in a Bruker minispec mq20 spectrometer. Figure 3a shows two spin-echo spectra acquired before and after the chemical reaction, without digital filter (reproduced from Prina et al [31] ).…”

Section: Phd-phip At Low Fieldmentioning

confidence: 99%

Discrimination of PHIP Signals Through their Evolution in Multipulse Sequences

et al. 2021

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The antiphase character of the PHIP associated signals after a hydrogenation reaction is particularly sensitive to line broadening introduced by magnetic field inhomogeneities and interferences by the presence of resonance lines steaming from a large amount of thermally polarized spins. These obstacles impose a limitation in the detection of reaction products as well as in the experimental setups. A simple way to overcome these impediments consists of acquiring the signal with a train of refocusing pulses instead of a single r.f. pulse. We present here a number of examples where this multipulse acquisition, denominated PhD-PHIP, displays its potentiality in improving the information related to hyperpolarized spins performed in a sample, where the former parahydrogen nuclei are part of a complex J-coupling network.

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