Investigating Catalytic Processes with Parahydrogen: Evolution of Zero-Quantum Coherence in AA′X Spin Systems

Natterer, Johannes; Schedletzky, O.; Barkemeyer, Jens; Bargon, Joachim; Glaser, Steffen J.

doi:10.1006/jmre.1998.1421

Cited by 61 publications

(58 citation statements)

References 26 publications

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“…3(c) is calculated with a generalized version [25] of the three-spin density matrix described in Ref. [27] and is in good agreement with the experimental results [ Fig. 3(b)].…”

supporting

confidence: 79%

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

et al. 2013

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We report new phenomena in low-field 1 H nuclear magnetic resonance (NMR) spectroscopy using parahydrogen induced polarization (PHIP), enabling determination of chemical shift differences, , and the scalar coupling constant J. NMR experiments performed with thermal polarization in millitesla magnetic fields do not allow the determination of scalar coupling constants for homonuclear coupled spins in the inverse weak coupling regime ( < J). We show here that low-field PHIP experiments in the inverse weak coupling regime enable the precise determination of and J. Furthermore we experimentally prove that observed splittings are related to in a nonlinear way. Naturally abundant 13 C and 29 Si isotopes lead to heteronuclear J-coupled 1 H-multiplet lines with amplitudes significantly enhanced compared to the amplitudes for thermally prepolarized spins. PHIP-enhanced NMR in the millitesla regime allows us to measure characteristic NMR parameters in a single scan using samples containing rare spins in natural abundance. DOI: 10.1103/PhysRevLett.110.137602 PACS numbers: 76.60.Àk, 33.25.+k, 82.56.Ub The established approach to liquid-state NMR spectroscopy in high fields is based on resolving NMR lines probing chemical shifts, J-coupling constants, and multiplicity. Those parameters are easily extracted from the spectra, because high-field experiments are typically performed in the weak coupling regime, where ) J is valid. The clearly separated spectral lines allow identification of molecular structure. In the presence of rare spins additional heteronuclear J-coupled multiplets arise [1,2].In the last decades various hyperpolarization technologies [3][4][5][6] and sensitive detection schemes [7][8][9][10] have rekindled the interest in low-field NMR. High resolution NMR spectroscopy with hyperpolarized molecules has been demonstrated in the Earth's magnetic field and close to zero field [10][11][12][13]. PHIP, where singlet state order (parahydrogen) is transferred into large observable nuclear polarization, offers an attractive means of hyperpolarization [14][15][16][17][18]. NMR spectroscopy with hyperpolarized J-coupled spins at zero and close to zero field [19][20][21] has been demonstrated. In these cases the presence of rare spins (e.g., 15 N) in the molecule is required to yield observable transitions in J-coupled spin systems. Close to zero field there are still ambiguity problems for molecules with more than two chemical groups and the chemical shift information is lost [22]. The drawbacks of low-field NMR spectroscopy for pure 1 H spin-systems with thermal polarization are the low signal-to-noise ratio (SNR) and the loss of J-coupling and chemical shift information.We show striking differences between the spectra obtained by PHIP and thermal prepolarization in low magnetic fields. In the following we detail how low-field PHIP spectra provide access to J and in addition to benefitting from the inherent SNR enhancement that allows for single-shot acquisition of compounds containing rare spins in natural abundan...

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“…3(c) is calculated with a generalized version [25] of the three-spin density matrix described in Ref. [27] and is in good agreement with the experimental results [ Fig. 3(b)].…”

supporting

confidence: 79%

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

et al. 2013

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“…The intensity of heteronuclear hyperpolarization depends on all the J couplings involved in the spin system formed with para-hydrogen protons (27,28). In particular, if only one heteroatom coupled with para-hydrogen protons is considered, an AA 0 X spin system is formed (AA 0 , para-hydrogen protons; X, heteronucleus) providing that the para-hydrogenation reaction takes place at low magnetic field in ALTADENA (Adiabatic Longitudinal Transfer After Dissociation Engenders Nuclear Alignment) conditions (29).…”

Section: Heteronuclear Para-hydrogen Induced Polarizationmentioning

confidence: 99%

How to design ¹³C para‐hydrogen‐induced polarization experiments for MRI applications

Reineri¹,

Viale²,

Dastrù³

et al. 2010

Contrast Media & Molecular

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The application of hyperpolarization techniques for MRI purposes is gathering increasing attention, especially for nuclei such as (13)C or (129)Xe. Among the different proposed methods, ParaHydrogen Induced Polarization requires relatively cheap equipment. The setup of an MRI experiment by means of parahydrogen requires the application of skills and methodologies that derive from different fields of knowledge. The basic theory and a practical insight of this method are presented here. Parahydrogenation of alkynes, having a labelled (13)CO group adjacent to the triple bond, catalyzed by Rh(I) complexes containing a chelating phosphine, represents the best choice for producing and maintaining high heteronuclear polarization effect. In order to transform anti-phase into in-phase (net) (13)C polarization for MRI application it is necessary to set up the described magnetic field cycle procedure. In vitro and in vivo images have been acquired using fast imaging sequences (RARE and trueFISP).

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“…The amount of polarization transferred from parahydrogen protons (A and A 0 ) to heteronuclear resonances (X) (that is, 13 C) depends on the coupling asymmetry of the two parahydrogen protons with the X nucleus (J AX -J A 0 X /2*J AA 0 ) 27,28 . Therefore, heteronuclear polarization cannot be achieved if the target X nucleus is symmetrically coupled with the two protons.…”

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confidence: 99%

ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate

2015

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The advent of nuclear spins hyperpolarization techniques represents a breakthrough in the field of medical diagnoses by magnetic resonance imaging. Dynamic nuclear polarization (DNP) is the most widely used method, and hyperpolarized metabolites such as [1-13 C]-pyruvate are shown to report on status of tumours. Parahydrogen-induced polarization (PHIP) is a chemistry-based technique, easier to handle and much less expensive in respect to DNP, with significantly shorter polarization times. Its main limitation is the availability of unsaturated precursors for the target substrates; for instance, acetate and pyruvate cannot be obtained by direct incorporation of the parahydrogen molecule. Herein we report a method that allows us to achieve hyperpolarization in this kind of molecule by means of a tailored precursor containing a hydrogenable functionality that, after polarization transfer to the target 13 C moiety, is cleaved to obtain the metabolite of interest. The reported procedure can be extended to a number of other biologically relevant substrates.

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Investigating Catalytic Processes with Parahydrogen: Evolution of Zero-Quantum Coherence in AA′X Spin Systems

Cited by 61 publications

References 26 publications

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

How to design ¹³C para‐hydrogen‐induced polarization experiments for MRI applications

ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate

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Investigating Catalytic Processes with Parahydrogen: Evolution of Zero-Quantum Coherence in AA′X Spin Systems

Cited by 61 publications

References 26 publications

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

Fundamental Aspects of Parahydrogen Enhanced Low-Field Nuclear Magnetic Resonance

How to design 13C para‐hydrogen‐induced polarization experiments for MRI applications

ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate

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How to design ¹³C para‐hydrogen‐induced polarization experiments for MRI applications