1
|
Negroni M, Turhan E, Kress T, Ceillier M, Jannin S, Kurzbach D. Frémy’s Salt as a Low-Persistence Hyperpolarization Agent: Efficient Dynamic Nuclear Polarization Plus Rapid Radical Scavenging. J Am Chem Soc 2022; 144:20680-20686. [PMID: 36322908 PMCID: PMC9673139 DOI: 10.1021/jacs.2c07960] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
![]()
Nuclear magnetic resonance (NMR) spectroscopy is a key
technique
for molecular structure determination in solution. However, due to
its low sensitivity, many efforts have been made to improve signal
strengths and reduce the required substrate amounts. In this regard,
dissolution dynamic nuclear polarization (DDNP) is a versatile approach
as signal enhancements of over 10 000-fold are achievable.
Samples are signal-enhanced ex situ by transferring
electronic polarization from radicals to nuclear spins before dissolving
and shuttling the boosted sample to an NMR spectrometer for detection.
However, the applicability of DDNP suffers from one major drawback,
namely, paramagnetic relaxation enhancements (PREs) that critically
reduce relaxation times due to the codissolved radicals. PREs are
the primary source of polarization losses canceling the signal improvements
obtained by DNP. We solve this problem by using potassium nitrosodisulfonate
(Frémy’s salt) as polarization agent (PA), which provides
high nuclear spin polarization and allows for rapid scavenging under
mild reducing conditions. We demonstrate the potential of Frémy’s
salt, (i) showing that both 1H and 13C polarization
of ∼30% can be achieved and (ii) describing a hybrid sample
shuttling system (HySSS) that can be used with any DDNP/NMR combination
to remove the PA before NMR detection. This gadget mixes the hyperpolarized
solution with a radical scavenger and injects it into an NMR tube,
providing, within a few seconds, quantitatively radical-free, highly
polarized solutions. The cost efficiency and broad availability of
Frémy’s salt might facilitate the use of DDNP in many
fields of research.
Collapse
Affiliation(s)
- Mattia Negroni
- Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria
| | - Ertan Turhan
- Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria
| | - Thomas Kress
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K
| | - Morgan Ceillier
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs (UMR 5082) Université de Lyon/CNRS/Université Claude Bernard Lyon 1/ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Sami Jannin
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs (UMR 5082) Université de Lyon/CNRS/Université Claude Bernard Lyon 1/ENS de Lyon, 5 Rue de la Doua, 69100 Villeurbanne, France
| | - Dennis Kurzbach
- Faculty of Chemistry, Institute of Biological Chemistry, University Vienna, Währinger Straße 38, 1090 Vienna, Austria
| |
Collapse
|
2
|
Soundararajan M, Dubroca T, van Tol J, Hill S, Frydman L, Wi S. Proton-detected solution-state NMR at 14.1 T based on scalar-driven 13C Overhauser dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 343:107304. [PMID: 36228539 DOI: 10.1016/j.jmr.2022.107304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Overhauser dynamic nuclear polarization (ODNP) NMR of solutions at high fields is usually mediated by scalar couplings that polarize the nuclei of heavier, electron-rich atoms. This leaves 1H-detected NMR outside the realm of such studies. This study presents experiments that deliver 1H-detected NMR experiments on relatively large liquid volumes (60 ∼ 100 μL) and at high fields (14.1 T), while relying on ODNP enhancements. To this end 13C NMR polarizations were first enhanced by relying on a mechanism that utilizes e--13C scalar coupling interactions; the nuclear spin alignment thus achieved was then passed on to neighboring 1H for observation, by a reverse INEPT scheme relying on one-bond JCH-couplings. Such 13C →1H polarization transfer ported the 13C ODNP gains into the 1H, permitting detection at higher frequencies and with higher potential sensitivities. For a model solution of labeled 13CHCl3 comixed with a nitroxide-based TEMPO derivative as polarizing agent, an ODNP enhancement factor of ca. 5x could thus be imparted to the 1H signal. When applied to bigger organic molecules like 2-13C-phenylacetylene and 13C8-indole, ODNP enhancements in the 1.2-3x range were obtained. Thus, although handicapped by the lower γ of the 13C, enhancements could be imparted on the 1H thermal acquisitions in all cases. We also find that conventional 1H-13C nuclear Overhauser enhancements (NOEs) are largely absent in these solutions due to the presence of co-dissolved radicals, adding negligible gains and playing negligible roles on the scalar e-→13C ODNP transfer. Potential rationalizations of these effects as well as extensions of these experiments, are briefly discussed.
Collapse
Affiliation(s)
| | - Thierry Dubroca
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Johan van Tol
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Stephen Hill
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA; Department of Physics, Florida State University, Tallahassee, FL 32306, USA
| | - Lucio Frydman
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA; Department of Chemical and Biological Physics, Weizmann Institute of Sciences, 76100001 Rehovot, Israel.
| | - Sungsool Wi
- National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA.
| |
Collapse
|
3
|
Dey A, Banerjee A. Unusual Overhauser Dynamic Nuclear Polarization Behavior of Fluorinated Alcohols at Room Temperature. J Phys Chem B 2019; 123:10463-10469. [PMID: 31714083 DOI: 10.1021/acs.jpcb.9b08144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structure of fluorinated alcohols is a matter of considerable interest in view of wide-ranging biomolecular applications. The microheterogeneity of fluorinated alcohols in the liquid state, in particular, has been a matter of debate and discussion in recent years using experimental and theoretical methods, including neutron or X-ray diffraction, as well as density functional theory (DFT) and molecular dynamics (MD) simulations. Here, we show that 1H and 19F Overhauser dynamic nuclear polarization (ODNP) buildup curves in solution state at room temperature show unusual behavior that could offer a novel approach to investigate the structural heterogeneity and dynamics of such homogeneous liquids with improved sensitivity. A detailed analysis of multiexponential ODNP buildup curves as a function of microwave irradiation time is shown to evidence microheterogeneity in such systems. Experimental ODNP buildup rates are interpreted using simple motional models that yield the motional correlation times of the relevant species in solution. It may be emphasized that this information is not available from standard approaches of high-resolution nuclear magnetic resonance (NMR) spectroscopy. While the present study focuses on fluorinated alcohols, it is to be anticipated that this approach would be valuable in the study of molecular assemblies in the solution state, including peptides, surfactant systems, etc.
Collapse
Affiliation(s)
- Arnab Dey
- MRI-MRS Centre and Department of Chemistry , Indian Institute of Technology-Madras , Chennai 600036 , Tamil Nadu , India
| | - Abhishek Banerjee
- MRI-MRS Centre and Department of Chemistry , Indian Institute of Technology-Madras , Chennai 600036 , Tamil Nadu , India
| |
Collapse
|
4
|
Biller JR, Barnes R, Han S. Perspective of Overhauser dynamic nuclear polarization for the study of soft materials. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
5
|
Khramtsov VV, Bobko AA, Tseytlin M, Driesschaert B. Exchange Phenomena in the Electron Paramagnetic Resonance Spectra of the Nitroxyl and Trityl Radicals: Multifunctional Spectroscopy and Imaging of Local Chemical Microenvironment. Anal Chem 2017; 89:4758-4771. [PMID: 28363027 PMCID: PMC5513151 DOI: 10.1021/acs.analchem.6b03796] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This Feature overviews the basic principles of using stable organic radicals involved in reversible exchange processes as functional paramagnetic probes. We demonstrate that these probes in combination with electron paramagnetic resonance (EPR)-based spectroscopy and imaging techniques provide analytical tools for quantitative mapping of critical parameters of local chemical microenvironment. The Feature is written to be understandable to people who are laymen to the EPR field in anticipation of future progress and broad application of these tools in biological systems, especially in vivo, over the next years.
Collapse
Affiliation(s)
- Valery V. Khramtsov
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Andrey A. Bobko
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Mark Tseytlin
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| | - Benoit Driesschaert
- In Vivo Multifunctional Magnetic Resonance center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia 26506, United States
| |
Collapse
|
6
|
One-thousand-fold enhancement of high field liquid nuclear magnetic resonance signals at room temperature. Nat Chem 2017. [DOI: 10.1038/nchem.2723] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
7
|
Liu G, Liou SH, Enkin N, Tkach I, Bennati M. Photo-induced radical polarization and liquid-state dynamic nuclear polarization using fullerene nitroxide derivatives. Phys Chem Chem Phys 2017; 19:31823-31829. [DOI: 10.1039/c7cp06073d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Continuous wave laser irradiation of fullerene–nitroxide derivatives at room temperature leads to spin polarization and NMR signal enhancement of toluene solvent protons.
Collapse
Affiliation(s)
- Guoquan Liu
- RG EPR Spectroscopy
- Max Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Shu-Hao Liou
- RG EPR Spectroscopy
- Max Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Nikolay Enkin
- RG EPR Spectroscopy
- Max Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Igor Tkach
- RG EPR Spectroscopy
- Max Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Marina Bennati
- RG EPR Spectroscopy
- Max Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
- Department of Chemistry
| |
Collapse
|
8
|
van Meerten SGJ, Tayler MCD, Kentgens APM, van Bentum PJM. Towards Overhauser DNP in supercritical CO(2). JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 267:30-6. [PMID: 27082277 DOI: 10.1016/j.jmr.2016.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/01/2016] [Accepted: 04/03/2016] [Indexed: 05/14/2023]
Abstract
Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for (1)H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in (1)H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2.
Collapse
Affiliation(s)
- S G J van Meerten
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands
| | - M C D Tayler
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands
| | - A P M Kentgens
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands
| | - P J M van Bentum
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands.
| |
Collapse
|
9
|
van Bentum J, van Meerten B, Sharma M, Kentgens A. Perspectives on DNP-enhanced NMR spectroscopy in solutions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 264:59-67. [PMID: 26920831 DOI: 10.1016/j.jmr.2016.01.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/12/2016] [Accepted: 01/13/2016] [Indexed: 05/03/2023]
Abstract
More than 60 years after the seminal work of Albert Overhauser on dynamic nuclear polarization by dynamic cross relaxation of coupled electron-nuclear spin systems, the quest for sensitivity enhancement in NMR spectroscopy is as pressing as ever. In this contribution we will review the status and perspectives for dynamic nuclear polarization in the liquid state. An appealing approach seems to be the use of supercritical solvents that may allow an extension of the Overhauser mechanism towards common high magnetic fields. A complementary approach is the use of solid state DNP on frozen solutions, followed by a rapid dissolution or in-situ melting step and NMR detection with substantially enhanced polarization levels in the liquid state. We will review recent developments in the field and discuss perspectives for the near future.
Collapse
|
10
|
Wang X, Isley Iii WC, Salido SI, Sun Z, Song L, Tsai KH, Cramer CJ, Dorn HC. Optimization and prediction of the electron-nuclear dipolar and scalar interaction in 1H and 13C liquid state dynamic nuclear polarization. Chem Sci 2015; 6:6482-6495. [PMID: 30090267 PMCID: PMC6054052 DOI: 10.1039/c5sc02499d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 07/25/2015] [Indexed: 12/19/2022] Open
Abstract
During the last 10-15 years, dynamic nuclear polarization (DNP) has evolved as a powerful tool for hyperpolarization of NMR and MRI nuclides. However, it is not as well appreciated that solution-state dynamic nuclear polarization is a powerful approach to study intermolecular interactions in solution. For solutions and fluids, the 1H nuclide is usually dominated by an Overhauser dipolar enhancement and can be significantly increased by decreasing the correlation time (τc) of the substrate/nitroxide interaction by utilizing supercritical fluids (SF CO2). For molecules containing the ubiquitous 13C nuclide, the Overhauser enhancement is usually a profile of both scalar and dipolar interactions. For carbon atoms without an attached hydrogen, a dipolar enhancement usually dominates as we illustrate for sp2 hybridized carbons in the fullerenes, C60 and C70. However, the scalar interaction is dependent on a Fermi contact interaction which does not have the magnetic field dependence inherent in the dipolar interaction. For a comprehensive range of molecular systems we show that molecules that exhibit weakly acidic complexation interaction(s) with nitroxides provide corresponding large scalar enhancements. For the first time, we report that sp hybridized (H-C) alkyne systems, for example, the phenylacetylene-nitroxide system exhibit very large scalar dominated enhancements. Finally, we demonstrate for a wide range of molecular systems that the Fermi contact interaction can be computationally predicted via electron-nuclear hyperfine coupling and correlated with experimental 13C DNP enhancements.
Collapse
Affiliation(s)
- X Wang
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - W C Isley Iii
- Department of Chemistry and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455-0431 , USA .
| | - S I Salido
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - Z Sun
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - L Song
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - K H Tsai
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - C J Cramer
- Department of Chemistry and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455-0431 , USA .
| | - H C Dorn
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| |
Collapse
|
11
|
Küçük SE, Neugebauer P, Prisner TF, Sezer D. Molecular simulations for dynamic nuclear polarization in liquids: a case study of TEMPOL in acetone and DMSO. Phys Chem Chem Phys 2015; 17:6618-28. [PMID: 25665728 DOI: 10.1039/c4cp05832a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A computational strategy for calibrating, validating and analyzing molecular dynamics (MD) simulations to predict dynamic nuclear polarization (DNP) coupling factors and relaxivities of proton spins is presented. Simulations of the polarizing agent TEMPOL in liquid acetone and DMSO are conducted at low (infinite dilution) and high (1 M) concentrations of the free radical. Because DNP coupling factors and relaxivities are sensitive to the time scales of the molecular motions, the MD simulations are calibrated to reproduce the bulk translational diffusion coefficients of the pure solvents. The simulations are then validated by comparing with experimental dielectric relaxation spectra, which report on the rotational dynamics of the molecular electric dipole moments. The analysis consists of calculating spectral density functions (SDFs) of the magnetic dipole-dipole interaction between the electron spin of TEMPOL and nuclear spins of the solvent protons. Here, MD simulations are used in combination with an analytically tractable model of molecular motion. While the former provide detailed information at relatively short spin-spin distances, the latter includes contributions at large separations, all the way to infinity. The relaxivities calculated from the SDFs of acetone and DMSO are in excellent agreement with experiments at 9.2 T. For DMSO we calculate a coupling factor in agreement with experiment while for acetone we predict a value that is larger by almost 50%, suggesting a possibility for experimental improvement.
Collapse
Affiliation(s)
- Sami Emre Küçük
- Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı-Tuzla, 34956 Istanbul, Turkey.
| | | | | | | |
Collapse
|
12
|
van der Heijden GHA, Kentgens APM, van Bentum PJM. Liquid state dynamic nuclear polarization of ethanol at 3.4 T (95 GHz). Phys Chem Chem Phys 2014; 16:8493-502. [PMID: 24668422 DOI: 10.1039/c3cp55254c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic Nuclear Polarization (DNP) in the liquid state has become the focus of attention to improve the NMR sensitivity of mass limited samples. The Overhauser model predicts a fast reduction in DNP enhancement at high magnetic fields where the electron Larmor frequency exceeds the typical inverse correlation time of the magnetic interaction between an unpaired electron spin of a radical and proton spins of the solvent molecules. The Overhauser hard sphere model is able to predict quantitatively the DNP enhancement for water TEMPOL solutions. The increase in temperature due to dielectric heating of the sample acts to reduce the correlation times and allows a substantial Overhauser DNP. In this paper we extend the work done on water towards other small molecules, such as ethanol. Experimentally we observe a similar enhancement for all three proton groups in the ethanol molecule. The classical interpretation of the low field Overhauser experiments on ethanol invokes a very fast anisotropic rotation of the hydrogen bonded TEMPOL-ethanol complex to explain the fast relaxation of the OH proton. Here we will discuss W-band relaxation and DNP enhancement within this classical model. Although the description can be made quantitative, the invoked parameters do not seem to be realistic. We will propose an alternative model based on the dynamic interaction both in free collision and due to modulation of the hydrogen bond length of the complex.
Collapse
Affiliation(s)
- G H A van der Heijden
- Institute for Molecules and Materials, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands.
| | | | | |
Collapse
|
13
|
Neudert O, Raich HP, Mattea C, Stapf S, Münnemann K. An Alderman-Grant resonator for S-Band Dynamic Nuclear Polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 242:79-85. [PMID: 24607825 DOI: 10.1016/j.jmr.2014.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/31/2014] [Accepted: 02/01/2014] [Indexed: 06/03/2023]
Abstract
An Alderman-Grant resonator with resonance at 2GHz (S-Band) was simulated, developed and constructed for Dynamic Nuclear Polarization (DNP) experiments at 73mT. The resonator fits into magnet bores with a minimum diameter of 20mm and is compatible with standard 3mm NMR tubes. The compact resonator design achieves good separation of electric and magnetic fields and therefore can be used with comparatively large sample volumes with only small sample heating effects comparable to those obtained with optimized X- and W-Band DNP setups. The saturation efficiency and sample heating effects were investigated for Overhauser DNP experiments of aqueous solutions of TEMPOL radical, showing relative saturation better than 0.9 and sample heating not exceeding a few Kelvin even at high microwave power and long irradiation time. An application is demonstrated, combining the DNP setup with a commercial fast field cycling NMR relaxometer. Using this resonator design at low microwave frequencies can provide DNP polarization for a class of low-field and time-domain NMR experiments and therefore may enable new applications that benefit from increased sensitivity.
Collapse
Affiliation(s)
- Oliver Neudert
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
| | - Hans-Peter Raich
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
| | - Carlos Mattea
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany.
| | - Siegfried Stapf
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany.
| | - Kerstin Münnemann
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
| |
Collapse
|
14
|
Enkin N, Liu G, Tkach I, Bennati M. High DNP efficiency of TEMPONE radicals in liquid toluene at low concentrations. Phys Chem Chem Phys 2014; 16:8795-800. [DOI: 10.1039/c4cp00854e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic nuclear polarization in liquid toluene with TEMPONE radicals leads to high NMR signal enhancements at low polarizer concentrations.
Collapse
Affiliation(s)
- Nikolay Enkin
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Guoquan Liu
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Igor Tkach
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Marina Bennati
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| |
Collapse
|
15
|
Sezer D. Rationalizing Overhauser DNP of nitroxide radicals in water through MD simulations. Phys Chem Chem Phys 2014; 16:1022-32. [DOI: 10.1039/c3cp53565g] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
16
|
Sezer D. Computation of DNP coupling factors of a nitroxide radical in toluene: seamless combination of MD simulations and analytical calculations. Phys Chem Chem Phys 2013; 15:526-40. [DOI: 10.1039/c2cp42430d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
17
|
Neudert O, Mattea C, Spiess HW, Stapf S, Münnemann K. A comparative study of 1H and 19F Overhauser DNP in fluorinated benzenes. Phys Chem Chem Phys 2013; 15:20717-26. [DOI: 10.1039/c3cp52912f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|