scholarly journals Tracing Dynamic Nuclear Polarization Pathways Using Transition Metal - Nuclear Spin Rulers

2019 ◽  
Author(s):  
Sheetal Kumar Jain ◽  
Chung-Jui Yu ◽  
Blake Wilson ◽  
Tarnuma Tabassum ◽  
Danna E. Freedman ◽  
...  
Keyword(s):  
Transition Metal ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Pulse Shaping ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Protein Structures ◽  
Organic Radical ◽  
Waveform Generator ◽  
Low Sensitivity

<p><a></a>The ubiquitous technique of nuclear magnetic resonance (NMR) spectroscopy suffers from relatively low sensitivity due to the low polarization of nuclei. For decades, the technique of dynamic nuclear polarization (DNP) has been harnessed to increase the sensitivity of NMR, enabling detection of low abundance nuclei such as <sup>17</sup>O and elucidation of protein structures. Yet, the catalogue of DNP agents today is limited to organic radical species, accompanied by a handful of metal ions (Cr<sup>3+</sup>, Mn<sup>2+</sup>, and Gd<sup>3+</sup>). This study significantly expands the scope and catalogue of DNP with the first demonstration of amplification of nuclear spin polarization at a set distance from a transition metal center (V<sup>4+</sup>) that has g-values significantly varied from 2 and anisotropic EPR line that is more than 3GHz broad.We showed that <sup>1</sup>H NMR signal enhancements of up to 33 can be achieved at 6.9T field and 4K temperature using a home-built DNP instrumentation that allows microwave irradiation over a frequency range of more than 10 GHz with pulse shaping capabilities by arbitrary waveform generator. A series of systematically designed vanadyl complexes, with V<sup>4+</sup>-<sup>1</sup>H distances in range 4.0 Å to 13.6 Å, was used to trace the polarization pathway of DNP and determine the size of the spin-diffusion barrier.<br></p>

scholarly journals Tracing Dynamic Nuclear Polarization Pathways Using Transition Metal - Nuclear Spin Rulers

2019 ◽  
Author(s):  
Sheetal Kumar Jain ◽  
Chung-Jui Yu ◽  
Blake Wilson ◽  
Tarnuma Tabassum ◽  
Danna E. Freedman ◽  
...  
Keyword(s):  
Transition Metal ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Pulse Shaping ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Protein Structures ◽  
Organic Radical ◽  
Waveform Generator ◽  
Low Sensitivity

<p><a></a>The ubiquitous technique of nuclear magnetic resonance (NMR) spectroscopy suffers from relatively low sensitivity due to the low polarization of nuclei. For decades, the technique of dynamic nuclear polarization (DNP) has been harnessed to increase the sensitivity of NMR, enabling detection of low abundance nuclei such as <sup>17</sup>O and elucidation of protein structures. Yet, the catalogue of DNP agents today is limited to organic radical species, accompanied by a handful of metal ions (Cr<sup>3+</sup>, Mn<sup>2+</sup>, and Gd<sup>3+</sup>). This study significantly expands the scope and catalogue of DNP with the first demonstration of amplification of nuclear spin polarization at a set distance from a transition metal center (V<sup>4+</sup>) that has g-values significantly varied from 2 and anisotropic EPR line that is more than 3GHz broad.We showed that <sup>1</sup>H NMR signal enhancements of up to 33 can be achieved at 6.9T field and 4K temperature using a home-built DNP instrumentation that allows microwave irradiation over a frequency range of more than 10 GHz with pulse shaping capabilities by arbitrary waveform generator. A series of systematically designed vanadyl complexes, with V<sup>4+</sup>-<sup>1</sup>H distances in range 4.0 Å to 13.6 Å, was used to trace the polarization pathway of DNP and determine the size of the spin-diffusion barrier.<br></p>

Chemically Induced Dynamic Nuclear Polarization During Irradiation of Phenol in the Presence of Amides

1975 ◽  
Vol 53 (16) ◽  
pp. 2459-2464
Author(s):  
Shiv P. Vaish ◽  
Holger E. Chen ◽  
Micha Tomkiewicz ◽  
Robert D. McAlpine ◽  
Michael Cocivera
Keyword(s):  
Carbonyl Group ◽  
Spin Polarization ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Radical Pair ◽  
Hydroxybenzoic Acid ◽  
Nuclear Spin Polarization ◽  
Ph Values ◽  
Chemically Induced

Irradiation of D2O solutions containing various phenols with aliphatic amides at pH values between 9 and 12 results in nuclear spin polarization which is observed as n.m.r. emission signals during irradiation. No polarization is observed for the phenols which include tyrosine, cresol, p-hydroxybenzoic acid, phenol, and others. For the amides which include acetamide, propionamide, N-methylacetamide, and N,N-dimethylacetamide, polarization was observed for only the protons on the carbon bonded to the carbonyl group. Because excited phenolate ions are known to eject electrons, it is proposed that the radical RĊ(O−)NR2 is formed by reaction of the amide with the hydrated electron. The polarization observed for the amides can be explained by reaction of RĊ(O−)NR2 with a benzosemiquinone radical via a radical pair.

Inhomogeneous dynamic nuclear polarization of protons in a lamella-forming diblock copolymer investigated by a small-angle neutron scattering method

2011 ◽  
Vol 44 (3) ◽  
pp. 503-513 ◽  
Author(s):  
Yohei Noda ◽  
Takayuki Kumada ◽  
Takeji Hashimoto ◽  
Satoshi Koizumi
Keyword(s):  
Neutron Scattering ◽  
Diblock Copolymer ◽  
Dynamic Nuclear Polarization ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Second Order ◽  
Third Order ◽  
Proton Polarization

By combining two methods of selective doping of paramagnetic species into a microdomain and small-angle neutron scattering (SANS), thespatially inhomogeneous proton polarizationcreated by dynamic nuclear polarization (DNP) has been precisely evaluated. A lamella-forming diblock copolymer composed of polystyrene (PS) and polyisoprene (PI) block chains (PS-b-PI) was employed, the SANS profile of which clearly shows scattering peaks up to the third order due to interlamellar interference. As a source of electron spin for DNP, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) was doped into one or other of the microdomains; samples with PS or PI microdomains selectively doped with TEMPO are designated PS.-b-PI and PS-b-PI., respectively. The SANS intensity at the first- and third-order peaks is well reproduced by assuming that the proton polarization is homogeneous throughout the sample, but that at the second-order peak cannot be explained by this assumption. This anomaly regarding the second-order peak was successfully explained by a model postulating that proton polarization in a doped microdomain decreases with increasing distance from the interface with a neighbouring doped microdomain. The decrease in proton polarization at the centre of a doped microdomain was estimated to be 0.07 (2) for PS-b-PI.and 0.05 (1) for PS.-b-PI, relative to constant proton polarization in a doped microdomain. The inhomogeneous proton polarization results from two competing dynamic processes,i.e.spin diffusion from doped to undoped microdomains, and spin lattice relaxation occurring on the pathway of proton spin diffusion.

scholarly journals Maximizing NMR signal per unit time by facilitating the e–e–n cross effect DNP rate

2018 ◽  
Vol 20 (43) ◽  
pp. 27646-27657 ◽  
Author(s):  
Alisa Leavesley ◽  
Sheetal Jain ◽  
Ilia Kamniker ◽  
Hui Zhang ◽  
Suchada Rajca ◽  
...  
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Nuclear Spin Relaxation ◽  
Cross Effect ◽  
Spin Clusters

Dynamic nuclear polarization (DNP) efficiency is critically dependent on the properties of the radical, solvent, and solute, where electron spin clusters will shorten nuclear spin relaxation and enhance CE-DNP.

scholarly journals H2-decoupling-accelerated H1 spin diffusion in dynamic nuclear polarization with photoexcited triplet electrons

2010 ◽  
Vol 133 (15) ◽  
pp. 154504 ◽  
Author(s):  
M. Negoro ◽  
K. Nakayama ◽  
K. Tateishi ◽  
A. Kagawa ◽  
K. Takeda ◽  
...  
Keyword(s):  
Dynamic Nuclear Polarization ◽  
Nuclear Polarization ◽  
Spin Diffusion

scholarly journals Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups

2017 ◽  
Vol 8 (15) ◽  
pp. 3549-3555 ◽  
Author(s):  
Jean-Nicolas Dumez ◽  
Basile Vuichoud ◽  
Daniele Mammoli ◽  
Aurélien Bornet ◽  
Arthur C. Pinon ◽  
...  
Keyword(s):  
Dynamic Nuclear Polarization ◽  
Nuclear Spin ◽  
Nuclear Polarization ◽  
Methyl Groups ◽  
Spin States

Electron-driven spin diffusion supports crossing the diffusion barrier in MAS DNP

2018 ◽  
Vol 20 (16) ◽  
pp. 11418-11429 ◽  
Author(s):  
Johannes J. Wittmann ◽  
Michael Eckardt ◽  
Wolfgang Harneit ◽  
Björn Corzilius
Keyword(s):  
Dynamic Nuclear Polarization ◽  
Diffusion Barrier ◽  
Nuclear Polarization ◽  
Spin Diffusion ◽  
Hyperfine Interactions ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Diffusion Rates ◽  
Angle Spinning

Hyperfine interactions can quench homonuclear spin-diffusion in the direct vicinity of a polarizing agent in dynamic nuclear polarization (DNP). However, under magic-angle spinning (MAS), the same interactions may also enhance the spin-diffusion rates through an electron-driven spin diffusion (EDSD) mechanism introduced here.

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