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Biedenbänder T, Aladin V, Saeidpour S, Corzilius B. Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR. Chem Rev 2022; 122:9738-9794. [PMID: 35099939 DOI: 10.1021/acs.chemrev.1c00776] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Solid-state NMR with magic-angle spinning (MAS) is an important method in structural biology. While NMR can provide invaluable information about local geometry on an atomic scale even for large biomolecular assemblies lacking long-range order, it is often limited by low sensitivity due to small nuclear spin polarization in thermal equilibrium. Dynamic nuclear polarization (DNP) has evolved during the last decades to become a powerful method capable of increasing this sensitivity by two to three orders of magnitude, thereby reducing the valuable experimental time from weeks or months to just hours or days; in many cases, this allows experiments that would be otherwise completely unfeasible. In this review, we give an overview of the developments that have opened the field for DNP-enhanced biomolecular solid-state NMR including state-of-the-art applications at fast MAS and high magnetic field. We present DNP mechanisms, polarizing agents, and sample constitution methods suitable for biomolecules. A wide field of biomolecular NMR applications is covered including membrane proteins, amyloid fibrils, large biomolecular assemblies, and biomaterials. Finally, we present perspectives and recent developments that may shape the field of biomolecular DNP in the future.
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Affiliation(s)
- Thomas Biedenbänder
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Victoria Aladin
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Siavash Saeidpour
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
| | - Björn Corzilius
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.,Department Life, Light & Matter, University of Rostock, Albert-Einstein-Straße 25, 18059 Rostock, Germany
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2
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Carroll AM, Eaton S, Eaton G, Zilm KW. Electron spin relaxation of P1 centers in synthetic diamonds with potential as B 1 standards for DNP enhanced NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 322:106875. [PMID: 33307296 DOI: 10.1016/j.jmr.2020.106875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 11/01/2020] [Accepted: 11/10/2020] [Indexed: 06/12/2023]
Abstract
The microwave magnetic field, B1, in the non-resonant structures typically used for DNP-enhanced NMR is relatively small, so calibration via continuous wave (CW) power saturation requires a sample with longer spin lattice relaxation times than the samples used as CW standards in X-band cavities. HPHT diamonds have strong, easily observed EPR signals from P1 centers (nitrogen defects), and are indefinitely stable. This makes HPHT diamonds attractive as secondary standards for calibration of electron B1 field strength in a variety of experimental arrangements. The concentrations of P1 centers is also typically in the 30-200 ppm range, or equivalently 10-60 mM, and therefore the EPR relaxation observed is relevant to DNP enhanced NMR employing free radical polarizing agents at similar concentrations. Pulsed and CW saturation relaxation measurements T1 and T2 are compared at X-band. Under CW conditions the relevant T1T2 product of time constants in our samples at room temperature is found to be dominated by electron-electron spin diffusion, and the product is large enough that saturation will be possible with the B1 of typical DNP systems. The similarity of T1 and T2 values obtained by pulse measurements at X-band and Q-band suggests that the X-band results can be extrapolated to the higher EPR frequencies used for DNP experiments. The electron spin dynamics observed here in HPHT diamond samples identify them as useful model systems to better delineate the interplay of electron spin relaxation, magic angle spinning, and inhomogeneous microwave irradiation as they affect DNP enhancement.
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Affiliation(s)
- Anne M Carroll
- Department of Chemistry, Yale University, 350 Edwards Street, New Haven, CT 06511, United States
| | - Sandra Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States
| | - Gareth Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, United States
| | - Kurt W Zilm
- Department of Chemistry, Yale University, 350 Edwards Street, New Haven, CT 06511, United States
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3
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Abstract
Dynamic nuclear polarization (DNP) is one of the most prominent methods of sensitivity enhancement in nuclear magnetic resonance (NMR). Even though solid-state DNP under magic-angle spinning (MAS) has left the proof-of-concept phase and has become an important tool for structural investigations of biomolecules as well as materials, it is still far from mainstream applicability because of the potentially overwhelming combination of unique instrumentation, complex sample preparation, and a multitude of different mechanisms and methods available. In this review, I introduce the diverse field and history of DNP, combining aspects of NMR and electron paramagnetic resonance. I then explain the general concepts and detailed mechanisms relevant at high magnetic field, including solution-state methods based on Overhauser DNP but with a greater focus on the more established MAS DNP methods. Finally, I review practical considerations and fields of application and discuss future developments.
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Affiliation(s)
- Björn Corzilius
- Institute of Chemistry and Department of Life, Light and Matter, University of Rostock, 18059 Rostock, Germany;
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Gao C, Alaniva N, Saliba EP, Sesti EL, Judge PT, Scott FJ, Halbritter T, Sigurdsson ST, Barnes AB. Frequency-chirped dynamic nuclear polarization with magic angle spinning using a frequency-agile gyrotron. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 308:106586. [PMID: 31525550 DOI: 10.1016/j.jmr.2019.106586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/15/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate that frequency-chirped dynamic nuclear polarization (DNP) with magic angle spinning (MAS) improves the enhancement of nuclear magnetic resonance (NMR) signal beyond that of continuous-wave (CW) DNP. Using a custom, frequency-agile gyrotron we implemented frequency-chirped DNP using the TEMTriPol-1 biradical, with MAS NMR at 7 T. Frequency-chirped microwaves yielded a DNP enhancement of 137, an increase of 19% compared to 115 recorded with CW. The chirps were 120 MHz-wide and centered over the trityl resonance, with 7 W microwave power incident on the sample (estimated 0.4 MHz electron spin Rabi frequency). We describe in detail the design and fabrication of the frequency-agile gyrotron used for frequency-chirped MAS DNP. Improvements to the interaction cavity and internal mode converter yielded efficient microwave generation and mode conversion, achieving >10 W output power over a 335 MHz bandwidth with >110 W peak power. Frequency-chirped DNP with MAS is expected to have a significant impact on the future of magnetic resonance.
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Affiliation(s)
- Chukun Gao
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Nicholas Alaniva
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Edward P Saliba
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Erika L Sesti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Patrick T Judge
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Biochemistry, Biophysics & Structural Biology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Faith J Scott
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Thomas Halbritter
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Alexander B Barnes
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA; Physical Chemistry, ETH-Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland.
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Chen HY, Tycko R. Temperature-Dependent Nuclear Spin Relaxation Due to Paramagnetic Dopants Below 30 K: Relevance to DNP-Enhanced Magnetic Resonance Imaging. J Phys Chem B 2018; 122:11731-11742. [PMID: 30277390 DOI: 10.1021/acs.jpcb.8b07958] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamic nuclear polarization (DNP) can increase nuclear magnetic resonance (NMR) signal strengths by factors of 100 or more at low temperatures. In magnetic resonance imaging (MRI), signal enhancements from DNP potentially lead to enhancements in image resolution. However, the paramagnetic dopants required for DNP also reduce nuclear spin relaxation times, producing signal losses that may cancel the signal enhancements from DNP. Here we investigate the dependence of 1H NMR relaxation times, including T1ρ and T2, under conditions of Lee-Goldburg 1H-1H decoupling and pulsed spin locking, on temperature and dopant concentration in frozen solutions that contain the trinitroxide compound DOTOPA. We find that relaxation times become longer at temperatures below 10 K, where DOTOPA electron spins become strongly polarized at equilibrium in a 9.39 T magnetic field. We show that the dependences of relaxation times on temperature and DOTOPA concentration can be reproduced qualitatively (although not quantitatively) by detailed simulations of magnetic field fluctuations due to flip-flop transitions in a system of dipole-coupled electron spin magnetic moments. These results have implications for ongoing attempts to reach submicron resolution in inductively detected MRI at very low temperatures.
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Affiliation(s)
- Hsueh-Ying Chen
- Laboratory of Chemical Physics National Institute of Diabetes and Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Robert Tycko
- Laboratory of Chemical Physics National Institute of Diabetes and Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
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Björgvinsdóttir S, Walder BJ, Pinon AC, Emsley L. Bulk Nuclear Hyperpolarization of Inorganic Solids by Relay from the Surface. J Am Chem Soc 2018; 140:7946-7951. [DOI: 10.1021/jacs.8b03883] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Snædís Björgvinsdóttir
- Institut des Sciences et Ingéniere Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Brennan J. Walder
- Institut des Sciences et Ingéniere Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Arthur C. Pinon
- Institut des Sciences et Ingéniere Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingéniere Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Kwiatkowski G, Jähnig F, Steinhauser J, Wespi P, Ernst M, Kozerke S. Direct hyperpolarization of micro- and nanodiamonds for bioimaging applications - Considerations on particle size, functionalization and polarization loss. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 286:42-51. [PMID: 29183003 DOI: 10.1016/j.jmr.2017.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 11/13/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
Due to the inherently long relaxation time of 13C spins in diamond, the nuclear polarization enhancement obtained with dynamic nuclear polarization can be preserved for a time on the order of about one hour, opening up an opportunity to use diamonds as a new class of long-lived contrast agents. The present communication explores the feasibility of using 13C spins in directly hyperpolarized diamonds for MR imaging including considerations for potential in vivo applications.
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Affiliation(s)
| | - Fabian Jähnig
- Laboratory of Physical Chemistry, ETH Zurich, Switzerland
| | - Jonas Steinhauser
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland
| | - Patrick Wespi
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland
| | - Matthias Ernst
- Laboratory of Physical Chemistry, ETH Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Switzerland.
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Sergeev NA, Panich AM, Olszewski M, Shenderova O, Goren SD. (13)C spin-lattice relaxation in nanodiamonds in static and magic angle spinning regimes. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 66-67:51-55. [PMID: 25465482 DOI: 10.1016/j.ssnmr.2014.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/08/2014] [Accepted: 10/10/2014] [Indexed: 06/04/2023]
Abstract
We report on (13)C nuclear spin-lattice relaxation time (T1) dependence on the magic-angle-spinning (MAS) rate in powder nanodiamond samples. We confirm that the relaxation is caused by interaction of nuclear spins with fluctuating electron spins of localized paramagnetic defects. It was found that T1 is practically not affected by MAS for small particles, while for larger particles with lower defect density T1 is different in static and MAS regimes and reveals elongation with increasing MAS rate. This effect is attributed to suppression of nuclear spin diffusion by MAS. We propose an approach that describes T1 dependence on the MAS rate and allows quantitative analysis of this effect.
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Affiliation(s)
- N A Sergeev
- Institute of Physics, University of Szczecin, 70-451 Szczecin, Poland
| | - A M Panich
- Department of Physics, Ben-Gurion University of the Negev, P. O. Box 653, Be'er Sheva 8410501, Israel.
| | - M Olszewski
- Institute of Physics, University of Szczecin, 70-451 Szczecin, Poland
| | - O Shenderova
- International Technology Center, Raleigh, North Carolina 27617, United States
| | - S D Goren
- Department of Physics, Ben-Gurion University of the Negev, P. O. Box 653, Be'er Sheva 8410501, Israel
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9
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Rossini AJ, Zagdoun A, Lelli M, Lesage A, Copéret C, Emsley L. Dynamic nuclear polarization surface enhanced NMR spectroscopy. Acc Chem Res 2013; 46:1942-51. [PMID: 23517009 DOI: 10.1021/ar300322x] [Citation(s) in RCA: 409] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many of the functions and applications of advanced materials result from their interfacial structures and properties. However, the difficulty in characterizing the surface structure of these materials at an atomic level can often slow their further development. Solid-state NMR can probe surface structure and complement established surface science techniques, but its low sensitivity often limits its application. Many materials have low surface areas and/or low concentrations of active/surface sites. Dynamic nuclear polarization (DNP) is one intriguing method to enhance the sensitivity of solid-state NMR experiments by several orders of magnitude. In a DNP experiment, the large polarization of unpaired electrons is transferred to surrounding nuclei, which provides a maximum theoretical DNP enhancement of ∼658 for (1)H NMR. In this Account, we discuss the application of DNP to enhance surface NMR signals, an approach known as DNP surface enhanced NMR spectroscopy (DNP SENS). Enabling DNP for these systems requires bringing an exogeneous radical solution into contact with surfaces without diluting the sample. We proposed the incipient wetness impregnation technique (IWI), a well-known method in materials science, to impregnate porous and particulate materials with just enough radical containing solution to fill the porous volume. IWI offers several advantages: it is extremely simple, provides a uniform wetting of the surface, and does not increase the sample volume or substantially reduce the concentration of the sample. This Account describes the basic principles behind DNP SENS through results obtained for mesoporous and nanoparticulate samples impregnated with radical solutions. We also discuss the quantification of the overall sensitivity enhancements obtained with DNP SENS and compare that with ordinary room temperature NMR spectroscopy. We then review the development of radicals and solvents that give the best possible enhancements today. With the best polarizing mixtures, DNP SENS enhances sensitivity by a factor of up to 100, which decreases acquisition time by five orders of magnitude. Such enhancement enables the detailed and expedient atomic level characterization of the surfaces of complex materials at natural isotopic abundance and opens new avenues for NMR. To illustrate these improvements, we describe the successful application of DNP SENS to characterize hybrid materials, organometallic surface species, and metal-organic frameworks.
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Affiliation(s)
- Aaron J. Rossini
- Centre de RMN a Tres Hauts Champs, Universite de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
| | - Alexandre Zagdoun
- Centre de RMN a Tres Hauts Champs, Universite de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
| | - Moreno Lelli
- Centre de RMN a Tres Hauts Champs, Universite de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
| | - Anne Lesage
- Centre de RMN a Tres Hauts Champs, Universite de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
| | - Christophe Copéret
- Department of Chemistry, Laboratory of Inorganic Chemistry, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Lyndon Emsley
- Centre de RMN a Tres Hauts Champs, Universite de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France
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Freitas J, Cunha A, Emmerich F. Solid-State Nuclear Magnetic Resonance (NMR) Methods Applied to the Study of Carbon Materials. ACTA ACUST UNITED AC 2012. [DOI: 10.1201/b12960-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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11
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Hu KN. Polarizing agents and mechanisms for high-field dynamic nuclear polarization of frozen dielectric solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2011; 40:31-41. [PMID: 21855299 PMCID: PMC3171565 DOI: 10.1016/j.ssnmr.2011.08.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 08/01/2011] [Accepted: 08/01/2011] [Indexed: 05/05/2023]
Abstract
This article provides an overview of polarizing mechanisms involved in high-frequency dynamic nuclear polarization (DNP) of frozen biological samples at temperatures maintained using liquid nitrogen, compatible with contemporary magic-angle spinning (MAS) nuclear magnetic resonance (NMR). Typical DNP experiments require unpaired electrons that are usually exogenous in samples via paramagnetic doping with polarizing agents. Thus, the resulting nuclear polarization mechanism depends on the electron and nuclear spin interactions induced by the paramagnetic species. The Overhauser Effect (OE) DNP, which relies on time-dependent spin-spin interactions, is excluded from our discussion due the lack of conducting electrons in frozen aqueous solutions containing biological entities. DNP of particular interest to us relies primarily on time-independent, spin-spin interactions for significant electron-nucleus polarization transfer through mechanisms such as the Solid Effect (SE), the Cross Effect (CE) or Thermal Mixing (TM), involving one, two or multiple electron spins, respectively. Derived from monomeric radicals initially used in high-field DNP experiments, bi- or multiple-radical polarizing agents facilitate CE/TM to generate significant NMR signal enhancements in dielectric solids at low temperatures (<100 K). For example, large DNP enhancements (∼300 times at 5 T) from a biologically compatible biradical, 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL), have enabled high-resolution MAS NMR in sample systems existing in submicron domains or embedded in larger biomolecular complexes. The scope of this review is focused on recently developed DNP polarizing agents for high-field applications and leads up to future developments per the CE DNP mechanism. Because DNP experiments are feasible with a solid-state microwave source when performed at <20K, nuclear polarization using lower microwave power (<100 mW) is possible by forcing a high proportion of biradicals to fulfill the frequency matching condition of CE (two EPR frequencies separated by the NMR frequency) using the strategies involving hetero-radical moieties and/or molecular alignment. In addition, the combination of an excited triplet and a stable radical might provide alternative DNP mechanisms without the microwave requirement.
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Affiliation(s)
- Kan-Nian Hu
- Laboratory of Chemical Physics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Fang X, Mao J, Levin EM, Schmidt-Rohr K. Nonaromatic Core−Shell Structure of Nanodiamond from Solid-State NMR Spectroscopy. J Am Chem Soc 2009; 131:1426-35. [DOI: 10.1021/ja8054063] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- XiaoWen Fang
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, Ames Laboratory DOE, Ames, Iowa 50011, and Department of Physics and Astronomy, Iowa State University, Iowa 50011
| | - JingDong Mao
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, Ames Laboratory DOE, Ames, Iowa 50011, and Department of Physics and Astronomy, Iowa State University, Iowa 50011
| | - E. M. Levin
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, Ames Laboratory DOE, Ames, Iowa 50011, and Department of Physics and Astronomy, Iowa State University, Iowa 50011
| | - Klaus Schmidt-Rohr
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia 23529, Ames Laboratory DOE, Ames, Iowa 50011, and Department of Physics and Astronomy, Iowa State University, Iowa 50011
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Hu KN, Bajaj VS, Rosay M, Griffin RG. High-frequency dynamic nuclear polarization using mixtures of TEMPO and trityl radicals. J Chem Phys 2007; 126:044512. [PMID: 17286492 DOI: 10.1063/1.2429658] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In a previous communication [Hu et al., J. Am. Chem. Soc. 126, 10844 (2004)], an approach was demonstrated that improves the efficiency of the cross-effect polarization mechanism employed in high field dynamic nuclear polarization (DNP) experiments. Specifically, it was shown that tethering two TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) radicals increases the electron-electron dipole coupling from approximately 1 MHz in solutions of monomeric TEMPO to approximately 25 MHz in a tethered biradical. The larger coupling resulted in an increase in the DNP enhancements by a factor of approximately 3-4, from 45-50 to approximately 165. Here, a second approach to improving the efficiency of the polarization process is described that involves approximately satisfying the matching condition |omega(2e)-omega(1e)|=omega(n), where omega(2e) and omega(1e) are two frequencies in the electron paramagnetic resonance (EPR) spectrum and omega(n) is the Larmor frequency of the nuclear spins being polarized. Specifically, in a mixture of TEMPO and trityl [tris (8-carboxy-2,2,6,6-tetramethyl(-d3)-benzo[1,2d:4,5-d']bis(1,3)dithiol-4-yl) methyl] radicals, the intensity maxima in the EPR spectra of these two species are approximately separated by the (1)H NMR frequency. In this case the frequency difference between the g(yy) value of TEMPO and the narrow pseudo-isotropic g-value of trityl is approximately 224 MHz and the (1)H Larmor frequency is 211 MHz. The optimal magnetic field for DNP using the mixtures was found to coincide with the trityl EPR resonance. At 90 K and 5 T, a mixture of 20 mM TEMPO and 20 mM trityl enhanced the (1)H polarization by a factor of approximately 160, an improvement over the enhancement of approximately 50 with 40 mM TEMPO. The reasons for the improvement are discussed and evidence is presented suggesting that DNP enhancement can be improved further by tethering TEMPO and trityl or two similar radicals.
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Affiliation(s)
- Kan-Nian Hu
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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14
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Komatsu N, Kadota N, Kimura T, Osawa E. Solution-phase13C NMR Spectroscopy of Detonation Nanodiamond. CHEM LETT 2007. [DOI: 10.1246/cl.2007.398] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Rovnyak D, Baldus M, Itin BA, Bennati M, Stevens A, Griffin RG. Characterization of a Carbon−Nitrogen Network Solid with NMR and High Field EPR. J Phys Chem B 2000. [DOI: 10.1021/jp0004157] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David Rovnyak
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
| | - Marc Baldus
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
| | - Boris A. Itin
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
| | - Marina Bennati
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
| | - Andrew Stevens
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
| | - Robert G. Griffin
- MIT/Harvard Center for Magnetic Resonance and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Chemistry, Harvard University, Cambridge, Massachusetts 02139
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16
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Reynhardt EC, High GL. Dynamic nuclear polarization of diamond. III. Paramagnetic electron relaxation times from enhanced 13C nuclear magnetic resonance signals. J Chem Phys 2000. [DOI: 10.1063/1.481849] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Hu JZ, Solum MS, Wind RA, Nilsson BL, Peterson MA, Pugmire RJ, Grant DM. H and 15N Dynamic Nuclear Polarization Studies of Carbazole. J Phys Chem A 2000. [DOI: 10.1021/jp9938011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jian Z. Hu
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - Mark S. Solum
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - Robert A. Wind
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - Brad L. Nilsson
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - Matt A. Peterson
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - Ronald J. Pugmire
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
| | - David M. Grant
- Departments of Chemistry and Chemical and Fuels Engineering, University of Utah, Salt Lake City, Utah 84112, Environmental and Molecular Sciences Laboratory, Battelle Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, Department of Chemistry, Brigham Young University, Provo, Utah 84602
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Reynhardt EC, High GL. Dynamic nuclear polarization of diamond. I. Solid state and thermal mixing effects. J Chem Phys 1998. [DOI: 10.1063/1.477009] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Reynhardt EC, High GL. Dynamic nuclear polarization of diamond. II. Nuclear orientation via electron spin-locking. J Chem Phys 1998. [DOI: 10.1063/1.477010] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shabanova E, Schaumburg K, Sellschop JPF. 13C NMR Investigations of Spin-Lattice Relaxation in 99% 13C-Enriched Diamonds. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 1998; 130:8-17. [PMID: 9469891 DOI: 10.1006/jmre.1997.1283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The paper is devoted to investigations of spin-lattice relaxation processes in 99% 13C-enriched diamonds. Relaxation time measurements were performed as a function of orientation, magnetic field, and temperature. Both experimental results and theoretical discussion are presented. Multiexponential behavior of nuclear magnetization recovery was observed. There was found no significant influence of the diamond orientation on the nuclear spin-lattice relaxation. The field dependence of the spin-lattice relaxation time was found to be proportional to the second power of the magnetic field. The temperature measurements showed a weak increase of the spin-lattice relaxation time with decreasing temperature. Possible mechanisms of impurity relaxation are considered and compared with the experimental data. Copyright 1998 Academic Press. Copyright 1998 Academic Press
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Affiliation(s)
- E Shabanova
- CISMI, University of Copenhagen, Symbion Science Park, Fruebjergvej 3, Copenhagen, DK-2100, Denmark
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Hu JZ, Zhou J, Yang B, Li L, Qiu J, Ye C, Solum MS, Wind RA, Pugmire RJ, Grant DM. Dynamic nuclear polarization of nitrogen-15 in benzamide. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1997; 8:129-137. [PMID: 9203286 DOI: 10.1016/s0926-2040(96)01263-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A 15N dynamic nuclear polarization (DNP) experiment is reported in which a 15N DNP enhancement factor of approximately 2.6 x 10(2) is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of alpha, gamma-bisdiphenylene-beta-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.
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Affiliation(s)
- J Z Hu
- Laboratory of Magnetic Resonance, and Atomic and Molecular Physics, Wuhan Institute of Physics, Chinese Academy of Sciences, People's Republic of China
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Zhou J, Yang B, Hu J, Hu H, Li L, Qiu J, Zeng F, Ye C. Investigation of a naphthalene pitch by high-resolution solid-state dynamic nuclear polarization. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1996; 6:127-133. [PMID: 8784951 DOI: 10.1016/0926-2040(95)01218-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The possibility of applying the dynamic nuclear polarization (DNP) technique to a study of char is explored with a naphthalene-derived pitch. It is shown that a 13C DNP enhancement factor of about 10(2) is obtained when the polarization is directly transferred from the unpaired electrons to the 13C nuclei. An undistorted spectrum with an enhancement factor of 8 is obtained by the DNP cross-polarization magic-angle spinning nuclear magnetic resonance (DNP-CP-MAS NMR) method. With such a high increase in S/N, it is possible to measure the 13C polarization time (Tp) and the spin-lattice relaxation time (T1) of the system in a reasonable experimental time. The resultant values are Tp = 19 s and T1 = 38 s, respectively. Based on the DNP enhancement as a function of the microwave frequency, it is found that the predominant DNP mechanism in the pitch is the solid-state effect.
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Affiliation(s)
- J Zhou
- Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics, Chinese Academy of Sciences, People's Republic of China
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Zhou J, Li L, Hu H, Yang B, Dan Z, Qiu J, Guo J, Chen F, Ye C. Study of natural diamonds by dynamic nuclear polarization-enhanced 13C nuclear magnetic resonance spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1994; 3:339-351. [PMID: 7842279 DOI: 10.1016/0926-2040(94)90018-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The results of a study of two types of natural-diamond crystals by dynamic nuclear polarization (DNP)-enhanced high-resolution solid-state 13C nuclear magnetic resonance (NMR) are reported. The home-built DNP magic-angle spinning (MAS) 13C NMR spectrometer operates at 54 GHz for electrons and 20.2 MHz for carbons. The power of the microwave source was about 30 W and the highest DNP enhancement factor came near to 10(3). It was shown that in the MAS spectra the 13C NMR linewidths of the Ib-type diamond were broader than those of IaB3-type diamond. From the hyperfine structure of the DNP enhancement as a function of frequency, four kinds of nitrogen-centred and one kind of carbon-centred free radicals could be identified in the Ib-type diamond. The hyperfine structures of the DNP enhancement curve that originated from the anisotropic hyperfine interaction between electron and nuclei could be partially averaged out by MAS. The 13C polarization time of DNP was rather long, i.e. 1500 s, and the spin-lattice relaxation time (without microwave irradiation) was about 300 s, which was somewhat shorter than anticipated. Discussions on these experimental results have been made in this report.
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Affiliation(s)
- J Zhou
- Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics, Chinese Academy of Sciences, Wuhan
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Hoch MJ, Reynhardt EC. Nuclear spin-lattice relaxation of dilute spins in semiconducting diamond. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:9222-9226. [PMID: 9944305 DOI: 10.1103/physrevb.37.9222] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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A quantitative investigation of the dynamic nuclear polarization effect by fixed paramagnetic centra of abundant and rare spins in solids at room temperature. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0378-4363(86)90503-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mark Henrichs P, Cofield ML, Young RH, Michael Hewitt J. Nuclear spin-lattice relaxation via paramagnetic centers in solids. 13C NMR of diamonds. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0022-2364(84)90009-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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