Effect of low and zero magnetic field on the hyperpolarization lifetime in parahydrogenated perdeuterated molecules

Reineri, Francesca; Santelia, Daniela; Gobetto, Roberto; Aime, Silvio

doi:10.1016/j.jmr.2009.05.009

Cited by 10 publications

(8 citation statements)

References 14 publications

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“…Transforming these states into longitudinal heteronuclear magnetization maximizes spectral dispersion during subsequent imaging experiments and reduces interference from the intense proton background arising from water in vivo. It has recently been demonstrated that parahydrogen singlet states can themselves be long-lived at Earth’s field, 12 but even in cases where the parahydrogen proton lifetimes are similar to or even more favorable than carbonyl 13 C for example, locking the initial spin order also eliminates the need to synchronize subsequent imaging with ongoing evolution of the initial parahydrogen singlet state.…”

Section: Introductionmentioning

confidence: 99%

Efficient Transformation of Parahydrogen Spin Order into Heteronuclear Magnetization

et al. 2013

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Spin order obtained in the strong coupling regime of protons from parahydrogen-induced hyperpolarization (PHIP) is initially captured as an ensemble of singlet states. For biomedical applications of PHIP, locking this spin order on long-lived heteronuclear storage nuclei increases spectral dispersion, reduces background interference from water protons, and eliminates the need to synchronize subsequent detection pulse sequences to accrued singlet-state evolution. A variety of traditional sequences such as INEPT or HMQC are available to interconvert heteronuclear single quantum coherences at high field, but new approaches are required for converting singlet states into heteronuclear single quantum coherences at low field in the strong coupling regime of protons. Described here is a consolidated pulse sequence that achieves this transformation of singlet-state spin order into heteronuclear magnetization across a wide range of scalar couplings in AA′X spin systems. Analytic solutions to the spin evolution are presented, and performance was validated experimentally in the parahydrogen addition product, 2-hydroxyethyl 1-13C-propionate-d3. Hyperpolarized carbon-13 signals were enhanced by a factor of several million relative to Boltzmann polarization in a static magnetic field of 47.5 mT (~13% polarization). We anticipate that this pulse sequence will provide efficient conversion of parahydrogen spin order over a broad range of emerging PHIP agents that feature AA′X spin systems.

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Section: Introductionmentioning

confidence: 99%

Efficient Transformation of Parahydrogen Spin Order into Heteronuclear Magnetization

et al. 2013

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“…In this case, 3,4,5-trideuteriopyridine delivered a 60% improvement in the ortho 1 H polarization level. A further benefit of 2 H labeling is to extend the lifetime of the created nuclear spin states. , The appropriate combination of magnetic field, reagent concentrations, and 2 H labeling is therefore necessary to maximize the hyperpolarization level using this method.…”

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confidence: 99%

Iridium N-Heterocyclic Carbene Complexes as Efficient Catalysts for Magnetization Transfer from para-Hydrogen

et al. 2011

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While the characterization of materials by NMR is hugely important in the physical and biological sciences, it also plays a vital role in medical imaging. This success is all the more impressive because of the inherently low sensitivity of the method. We establish here that [Ir(H)2(IMes)(py)3]Cl undergoes both pyridine (py) loss as well as the reductive elimination of H2. These reversible processes bring para-H2 and py into contact in a magnetically coupled environment, delivering an 8100-fold increase in 1H NMR signal strength relative to non-hyperpolarized py at 3 T. An apparatus that facilitates signal averaging has been built to demonstrate that the efficiency of this process is controlled by the strength of the magnetic field experienced by the complex during the magnetization transfer step. Thermodynamic and kinetic data combined with DFT calculations reveal the involvement of [Ir(H)2(η2-H2)(IMes)(py)2]+, an unlikely yet key intermediate in the reaction. Deuterium labeling yields an additional 60% improvement in signal, an observation that offers insight into strategies for optimizing this approach.

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“…In particular, it was calculated that, when the first passage took 10 ms, about 1.5% polarization was transferred to 13 C net magnetization of the acrylate hydrogenation product and about 10% when the passage took 50 ms. Since relaxation processes at nearly zero magnetic field might lead to fast polarization decay, 34 the first fast passage must preferably take less than 10 ms.…”

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confidence: 99%

Effects of Magnetic Field Cycle on the Polarization Transfer from Parahydrogen to Heteronuclei through Long-Range J-Couplings

et al. 2015

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Hyperpolarization of (13)C carboxylate signals of metabolically relevant molecules, such as acetate and pyruvate, was recently obtained by means of ParaHydrogen Induced Polarization by Side Arm Hydrogenation (PHIP-SAH). This method relies on functionalization of the carboxylic acid with an unsaturated alcohol (side arm), hydrogenation of the unsaturated alcohol using parahydrogen, and polarization transfer to the target (13)C signal. In this case, parahydrogen protons are added three to four bonds away from the target (13)C nucleus, while biologically relevant molecules had been hyperpolarized, using parahydrogen, through hydrogenation of an unsaturated bond adjacent to the target (13)C signal. The herein reported results show that the same polarization level can be obtained on the (13)C carboxylate signal of an ester by means of addition of parahydrogen to the acidic or to the alcoholic moiety and successive application of magnetic field cycle (MFC). Experimental results are supported by calculations that allow one to predict that, upon accurate control of magnetic field strength and speed of the passages, more than 20% polarization can be achieved on the (13)C-carboxylate resonance of the esters by means of side arm hydrogenation and MFC.

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Effect of low and zero magnetic field on the hyperpolarization lifetime in parahydrogenated perdeuterated molecules

Cited by 10 publications

References 14 publications

Efficient Transformation of Parahydrogen Spin Order into Heteronuclear Magnetization

Efficient Transformation of Parahydrogen Spin Order into Heteronuclear Magnetization

Iridium N-Heterocyclic Carbene Complexes as Efficient Catalysts for Magnetization Transfer from para-Hydrogen

Effects of Magnetic Field Cycle on the Polarization Transfer from Parahydrogen to Heteronuclei through Long-Range J-Couplings

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