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Robinson AD, Hill-Casey F, Duckett SB, Halse ME. Quantitative reaction monitoring using parahydrogen-enhanced benchtop NMR spectroscopy. Phys Chem Chem Phys 2024; 26:14317-14328. [PMID: 38695736 DOI: 10.1039/d3cp06221j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The parahydrogen-induced polarisation (PHIP) NMR signal enhancement technique is used to study H2 addition to Vaska's complex (trans-[IrCl(CO)(PPh3)2]) with both standard high-field (9.4 T) NMR and benchtop (1 T) NMR detection. Accurate and repeatable rate constants of (0.84 ± 0.03) dm3 mol-1 s-1 and (0.89 ± 0.03) dm3 mol-1 s-1 were obtained for this model system using standard high-field and benchtop NMR, respectively. The high-field NMR approach is shown to be susceptible to systematic errors associated with interference from non-hyperpolarised signals, which can be overcome through a multiple-quantum filtered acquisition scheme. This challenge is avoided when using benchtop NMR detection because the non-hyperpolarised signals are much weaker due to the lower magnetic field, enabling the use of a simpler and more efficient single RF pulse detection scheme. Method validation against several experimental parameters (NMR relaxation, %pH2 enrichment and temperature) demonstrates the robustness of the benchtop NMR approach but also highlights the need for sample temperature control throughout reaction monitoring. A simple temperature equilibration protocol, coupled with use of an insulated sample holder while manipulating the sample outside the spectrometer, is found to provide sufficient temperature stabilisation to ensure that accurate and repeatable rate constants are obtained. Finally, the benchtop NMR reaction monitoring protocol is applied to the analysis of a complex mixture, where multiple reaction products form simultaneously. H2 addition to a mixture of three Vaska's complex derivatives was monitored, revealing the presence of competitive reaction pathways within the mixture.
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2
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Czarnota M, Mames A, Pietrzak M, Jopa S, Theiß F, Buntkowsky G, Ratajczyk T. A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line. Angew Chem Int Ed Engl 2024; 63:e202309188. [PMID: 37727926 DOI: 10.1002/anie.202309188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/19/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
Abstract
The hydrogen molecule, which exists in two spin isomers (ortho- and parahydrogen), is a highly studied system due to its fundamental properties and practical applications. Parahydrogen is used for Nuclear Magnetic Resonance signal enhancement, which is hyperpolarization of other molecules, including biorelevant ones. Hyperpolarization can be achieved by using Signal Amplification by Reversible Exchange (SABRE). SABRE can also convert parahydrogen into orthohydrogen, and surprisingly, in some cases, it has been discovered that orthohydrogen's resonance has the Partially Negative Line (PNL) pattern. Here, an approach for obtaining orthohydrogen with a PNL signal is presented for two catalysts: Ir-IMes, and Ir-IMesBn. The type of solvent in which SABRE is conducted is crucial for the observation of PNL. Specifically, a PNL signal can be easily generated in benzene using both catalysts, but it is more intense for Ir-IMesBn. In acetone, PNL is observed only for Ir-IMesBn. In methanol, no PNL is detected. The PNL effect is only detectable during the initial steps of pre-catalyst activation, and disappears as the activation process progresses. We have proposed a working hypothesis that explains our results. The presented data may facilitate the further investigation of PNL and its applications in material science and catalysis.
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Affiliation(s)
- Marek Czarnota
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Adam Mames
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Sylwia Jopa
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warsaw, Poland
| | - Franziska Theiß
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Gerd Buntkowsky
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Tomasz Ratajczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
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3
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Snadin AV, Chuklina NO, Kiryutin AS, Lukzen NN, Yurkovskaya AV. Magnetic field dependence of the para-ortho conversion rate of molecular hydrogen in SABRE experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107630. [PMID: 38364339 DOI: 10.1016/j.jmr.2024.107630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 01/10/2024] [Accepted: 01/29/2024] [Indexed: 02/18/2024]
Abstract
The use of parahydrogen - the isomer of molecular hydrogen with zero nuclear spin - is important for promising and actively developing methods for spin hyperpolarization of nuclei called parahydrogen induced polarization (PHIP). However, the dissolved parahydrogen in PHIP experiments quickly loses its spin order, resulting in the formation of orthohydrogen and reduction of the overall nuclear polarization of the substrate. This process is due to the difference of chemical shifts of hydride protons, as well as spin-spin couplings between nuclei, in the intermediate catalytic complexes, and it has not been rigorously explained so far. We proposed a new experimental technique based on magnetic field cycling for measuring the rate of molecular hydrogen para-ortho conversion in solution and applied it for non-hydrogenative PHIP Signal Amplification By Reversible Exchange (SABRE) experiments. The para-ortho conversion rate was measured over a wide range of magnetic field from 0.5 mT to 9.4 T. It was found that the conversion rate strongly depends on the magnetic field in which the reaction occurs, as well as on the concentrations of reactants. The rate decreases with increasing the concentration of pyridine ligand and increases with increasing the concentration of iridium catalyst. The model, which takes into account the reversible exchange of molecular hydrogen with the catalyst, nuclear spin-spin interaction of hydride protons with nuclei of ligands within catalytic complex and nuclear Zeeman interactions, qualitatively describes the experimental data. Two types of complexes with different spin system symmetry contribute to the molecular hydrogen conversion. In asymmetric complexes possessing hydride protons with different chemical shifts due to the presence of chlorine anion ligand the para-ortho conversion rate increases with magnetic field, while for symmetric complexes this mechanism is not operable. In the magnetic field where level anti-crossing occurs the resonant feature for the rate of para-ortho conversion is found. The results of this work can be utilized for finding the optimal conditions for obtaining the maximum hyperpolarization in the experiments employing parahydrogen.
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Affiliation(s)
- Alexander V Snadin
- Novosibirsk State University, Novosibirsk 630090, Russia; Nesmeyanov Institute of Organoelement Compounds RAS, Moscow 119991, Russia
| | - Natalia O Chuklina
- International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Alexey S Kiryutin
- Novosibirsk State University, Novosibirsk 630090, Russia; International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia.
| | - Nikita N Lukzen
- Novosibirsk State University, Novosibirsk 630090, Russia; International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Alexandra V Yurkovskaya
- International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090, Russia
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4
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Ghorbani B, Zendehboudi S, Saady NMC, Duan X, Albayati TM. Strategies To Improve the Performance of Hydrogen Storage Systems by Liquefaction Methods: A Comprehensive Review. ACS OMEGA 2023; 8:18358-18399. [PMID: 37273600 PMCID: PMC10233851 DOI: 10.1021/acsomega.3c01072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/05/2023] [Indexed: 06/06/2023]
Abstract
The main challenges of liquid hydrogen (H2) storage as one of the most promising techniques for large-scale transport and long-term storage include its high specific energy consumption (SEC), low exergy efficiency, high total expenses, and boil-off gas losses. This article reviews different approaches to improving H2 liquefaction methods, including the implementation of absorption cooling cycles (ACCs), ejector cooling units, liquid nitrogen/liquid natural gas (LNG)/liquid air cold energy recovery, cascade liquefaction processes, mixed refrigerant systems, integration with other structures, optimization algorithms, combined with renewable energy sources, and the pinch strategy. This review discusses the economic, safety, and environmental aspects of various improvement techniques for H2 liquefaction systems in more detail. Standards and codes for H2 liquefaction technologies are presented, and the current status and future potentials of H2 liquefaction processes are investigated. The cost-efficient H2 liquefaction systems are those with higher production rates (>100 tonne/day), higher efficiency (>40%), lower SEC (<6 kWh/kgLH2), and lower investment costs (1-2 $/kgLH2). Increasing the stages in the conversion of ortho- to para-H2 lowers the SEC and increases the investment costs. Moreover, using low-temperature waste heat from various industries and renewable energy in the ACC for precooling is significantly more efficient than electricity generation in power generation cycles to be utilized in H2 liquefaction cycles. In addition, the substitution of LNG cold recovery for the precooling cycle is associated with the lower SEC and cost compared to its combination with the precooling cycle.
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Affiliation(s)
- Bahram Ghorbani
- Faculty
of Engineering and Applied Science, Memorial
University, St. John’s, Newfoundland and Labrador A1B
3X5, Canada
| | - Sohrab Zendehboudi
- Faculty
of Engineering and Applied Science, Memorial
University, St. John’s, Newfoundland and Labrador A1B
3X5, Canada
| | - Noori M. Cata Saady
- Faculty
of Engineering and Applied Science, Memorial
University, St. John’s, Newfoundland and Labrador A1B
3X5, Canada
| | - Xili Duan
- Faculty
of Engineering and Applied Science, Memorial
University, St. John’s, Newfoundland and Labrador A1B
3X5, Canada
| | - Talib M. Albayati
- Department
of Chemical Engineering, University of Technology—Iraq, Baghdad 10071, Iraq
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5
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Wang W, Wang Q, Xu J, Deng F. Understanding Heterogeneous Catalytic Hydrogenation by Parahydrogen-Induced Polarization NMR Spectroscopy. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
Affiliation(s)
- Weiyu Wang
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Qiang Wang
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Jun Xu
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Feng Deng
- National Centre for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
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6
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Chimenti RV, Daley J, Sack J, Necsutu J, Whiting N. Reconversion of Parahydrogen Gas in Surfactant-Coated Glass NMR Tubes. Molecules 2023; 28:2329. [PMID: 36903572 PMCID: PMC10004819 DOI: 10.3390/molecules28052329] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/23/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
The application of parahydrogen gas to enhance the magnetic resonance signals of a diversity of chemical species has increased substantially in the last decade. Parahydrogen is prepared by lowering the temperature of hydrogen gas in the presence of a catalyst; this enriches the para spin isomer beyond its normal abundance of 25% at thermal equilibrium. Indeed, parahydrogen fractions that approach unity can be attained at sufficiently low temperatures. Once enriched, the gas will revert to its normal isomeric ratio over the course of hours or days, depending on the surface chemistry of the storage container. Although parahydrogen enjoys long lifetimes when stored in aluminum cylinders, the reconversion rate is significantly faster in glass containers due to the prevalence of paramagnetic impurities that are present within the glass. This accelerated reconversion is especially relevant for nuclear magnetic resonance (NMR) applications due to the use of glass sample tubes. The work presented here investigates how the parahydrogen reconversion rate is affected by surfactant coatings on the inside surface of valved borosilicate glass NMR sample tubes. Raman spectroscopy was used to monitor changes to the ratio of the (J: 0 → 2) vs. (J: 1 → 3) transitions that are indicative of the para and ortho spin isomers, respectively. Nine different silane and siloxane-based surfactants of varying size and branching structures were examined, and most increased the parahydrogen reconversion time by 1.5×-2× compared with equivalent sample tubes that were not treated with surfactant. This includes expanding the pH2 reconversion time from 280 min in a control sample to 625 min when the same tube is coated with (3-Glycidoxypropyl)trimethoxysilane.
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Affiliation(s)
- Robert V. Chimenti
- Department of Physics & Astronomy, Rowan University, Glassboro, NJ 08028, USA
- Advanced Materials & Manufacturing Institute, Rowan University, Glassboro, NJ 08028, USA
| | - James Daley
- Department of Physics & Astronomy, Rowan University, Glassboro, NJ 08028, USA
| | - James Sack
- Department of Physics & Astronomy, Rowan University, Glassboro, NJ 08028, USA
| | - Jennifer Necsutu
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, USA
| | - Nicholas Whiting
- Department of Physics & Astronomy, Rowan University, Glassboro, NJ 08028, USA
- Department of Biological & Biomedical Sciences, Rowan University, Glassboro, NJ 08028, USA
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Buntkowsky G, Theiss F, Lins J, Miloslavina YA, Wienands L, Kiryutin A, Yurkovskaya A. Recent advances in the application of parahydrogen in catalysis and biochemistry. RSC Adv 2022; 12:12477-12506. [PMID: 35480380 PMCID: PMC9039419 DOI: 10.1039/d2ra01346k] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/23/2022] [Indexed: 12/15/2022] Open
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy and Magnetic Resonance Imaging (MRI) are analytical and diagnostic tools that are essential for a very broad field of applications, ranging from chemical analytics, to non-destructive testing of materials and the investigation of molecular dynamics, to in vivo medical diagnostics and drug research. One of the major challenges in their application to many problems is the inherent low sensitivity of magnetic resonance, which results from the small energy-differences of the nuclear spin-states. At thermal equilibrium at room temperature the normalized population difference of the spin-states, called the Boltzmann polarization, is only on the order of 10-5. Parahydrogen induced polarization (PHIP) is an efficient and cost-effective hyperpolarization method, which has widespread applications in Chemistry, Physics, Biochemistry, Biophysics, and Medical Imaging. PHIP creates its signal-enhancements by means of a reversible (SABRE) or irreversible (classic PHIP) chemical reaction between the parahydrogen, a catalyst, and a substrate. Here, we first give a short overview about parahydrogen-based hyperpolarization techniques and then review the current literature on method developments and applications of various flavors of the PHIP experiment.
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Affiliation(s)
- Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt Alarich-Weiss-Str. 8 D-64287 Darmstadt Germany
| | - Franziska Theiss
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt Alarich-Weiss-Str. 8 D-64287 Darmstadt Germany
| | - Jonas Lins
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt Alarich-Weiss-Str. 8 D-64287 Darmstadt Germany
| | - Yuliya A Miloslavina
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt Alarich-Weiss-Str. 8 D-64287 Darmstadt Germany
| | - Laura Wienands
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt Alarich-Weiss-Str. 8 D-64287 Darmstadt Germany
| | - Alexey Kiryutin
- International Tomography Center, Siberian Branch of the Russian Academy of Science Novosibirsk 630090 Russia
| | - Alexandra Yurkovskaya
- International Tomography Center, Siberian Branch of the Russian Academy of Science Novosibirsk 630090 Russia
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8
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Schmidt AB, Bowers CR, Buckenmaier K, Chekmenev EY, de Maissin H, Eills J, Ellermann F, Glöggler S, Gordon JW, Knecht S, Koptyug IV, Kuhn J, Pravdivtsev AN, Reineri F, Theis T, Them K, Hövener JB. Instrumentation for Hydrogenative Parahydrogen-Based Hyperpolarization Techniques. Anal Chem 2022; 94:479-502. [PMID: 34974698 PMCID: PMC8784962 DOI: 10.1021/acs.analchem.1c04863] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Andreas B. Schmidt
- Department of Radiology – Medical Physics, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Killianstr. 5a, Freiburg 79106, Germany
- German Cancer Consortium (DKTK), partner site Freiburg and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - C. Russell Bowers
- Department of Chemistry, University of Florida, 2001 Museum Road, Gainesville, Florida 32611, USA
- National High Magnetic Field Laboratory, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - Kai Buckenmaier
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Max-Planck-Ring 11, 72076, Tübingen, Germany
| | - Eduard Y. Chekmenev
- Intergrative Biosciences (Ibio), Department of Chemistry, Karmanos Cancer Institute (KCI), Wayne State University, 5101 Cass Ave, Detroit, MI 48202, United States
- Russian Academy of Sciences (RAS), Leninskiy Prospect, 14, 119991 Moscow, Russia
| | - Henri de Maissin
- Department of Radiology – Medical Physics, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Killianstr. 5a, Freiburg 79106, Germany
- German Cancer Consortium (DKTK), partner site Freiburg and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany
| | - James Eills
- Institute for Physics, Johannes Gutenberg University, D-55090 Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Helmholtz-Institut Mainz, 55128 Mainz, Germany
| | - Frowin Ellermann
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Am Botanischen Garten 14, 24118, Kiel, Germany
| | - Stefan Glöggler
- NMR Signal Enhancement Group Max Planck Institutefor Biophysical Chemistry Am Fassberg 11, 37077 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration of UMG Von-Siebold-Str. 3A, 37075 Göttingen, Germany
| | - Jeremy W. Gordon
- Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry St., San Francisco, CA, 94158, USA
| | | | - Igor V. Koptyug
- International Tomography Center, SB RAS, 3A Institutskaya St., Novosibirsk 630090, Russia
| | - Jule Kuhn
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Am Botanischen Garten 14, 24118, Kiel, Germany
| | - Andrey N. Pravdivtsev
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Am Botanischen Garten 14, 24118, Kiel, Germany
| | - Francesca Reineri
- Dept. Molecular Biotechnology and Health Sciences, Via Nizza 52, University of Torino, Italy
| | - Thomas Theis
- Departments of Chemistry, Physics and Biomedical Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Kolja Them
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Am Botanischen Garten 14, 24118, Kiel, Germany
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Am Botanischen Garten 14, 24118, Kiel, Germany
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9
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Bengs C, Dagys L, Moustafa GAI, Whipham JW, Sabba M, Kiryutin AS, Ivanov KL, Levitt MH. Nuclear singlet relaxation by chemical exchange. J Chem Phys 2021; 155:124311. [PMID: 34598559 DOI: 10.1063/5.0066182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The population imbalance between nuclear singlet states and triplet states of strongly coupled spin-1/2 pairs, also known as nuclear singlet order, is well protected against several common relaxation mechanisms. We study the nuclear singlet relaxation of 13C pairs in aqueous solutions of 1,2-13C2 squarate over a range of pH values. The 13C singlet order is accessed by introducing 18O nuclei in order to break the chemical equivalence. The squarate dianion is in chemical equilibrium with hydrogen-squarate (SqH-) and squaric acid (SqH2) characterized by the dissociation constants pK1 = 1.5 and pK2 = 3.4. Surprisingly, we observe a striking increase in the singlet decay time constants TS when the pH of the solution exceeds ∼10, which is far above the acid-base equilibrium points. We derive general rate expressions for chemical-exchange-induced nuclear singlet relaxation and provide a qualitative explanation of the TS behavior of the squarate dianion. We identify a kinetic contribution to the singlet relaxation rate constant, which explicitly depends on kinetic rate constants. Qualitative agreement is achieved between the theory and the experimental data. This study shows that infrequent chemical events may have a strong effect on the relaxation of nuclear singlet order.
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Affiliation(s)
- Christian Bengs
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | - Laurynas Dagys
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | - Gamal A I Moustafa
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | - James W Whipham
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | - Mohamed Sabba
- School of Chemistry, University of Southampton, Southampton, United Kingdom
| | | | | | - Malcolm H Levitt
- School of Chemistry, University of Southampton, Southampton, United Kingdom
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10
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Pokochueva EV, Burueva DB, Salnikov OG, Koptyug IV. Heterogeneous Catalysis and Parahydrogen-Induced Polarization. Chemphyschem 2021; 22:1421-1440. [PMID: 33969590 DOI: 10.1002/cphc.202100153] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 05/05/2021] [Indexed: 01/11/2023]
Abstract
Parahydrogen-induced polarization with heterogeneous catalysts (HET-PHIP) has been a subject of extensive research in the last decade since its first observation in 2007. While NMR signal enhancements obtained with such catalysts are currently below those achieved with transition metal complexes in homogeneous hydrogenations in solution, this relatively new field demonstrates major prospects for a broad range of advanced fundamental and practical applications, from providing catalyst-free hyperpolarized fluids for biomedical magnetic resonance imaging (MRI) to exploring mechanisms of industrially important heterogeneous catalytic processes. This review covers the evolution of the heterogeneous catalysts used for PHIP observation, from metal complexes immobilized on solid supports to bulk metals and single-atom catalysts and discusses the general visions for maximizing the obtained NMR signal enhancements using HET-PHIP. Various practical applications of HET-PHIP, both for catalytic studies and for potential production of hyperpolarized contrast agents for MRI, are described.
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Affiliation(s)
- Ekaterina V Pokochueva
- Laboratory of Magnetic Resonance Microimaging, International Tomography Center SB RAS, 3 A Institutskaya St., 630090, Novosibirsk, Russia.,Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russia
| | - Dudari B Burueva
- Laboratory of Magnetic Resonance Microimaging, International Tomography Center SB RAS, 3 A Institutskaya St., 630090, Novosibirsk, Russia.,Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russia
| | - Oleg G Salnikov
- Laboratory of Magnetic Resonance Microimaging, International Tomography Center SB RAS, 3 A Institutskaya St., 630090, Novosibirsk, Russia.,Novosibirsk State University, 2 Pirogova St., 630090, Novosibirsk, Russia.,Boreskov Institute of Catalysis SB RAS, 5 Acad. Lavrentiev Ave., 630090, Novosibirsk, Russia
| | - Igor V Koptyug
- Laboratory of Magnetic Resonance Microimaging, International Tomography Center SB RAS, 3 A Institutskaya St., 630090, Novosibirsk, Russia.,Boreskov Institute of Catalysis SB RAS, 5 Acad. Lavrentiev Ave., 630090, Novosibirsk, Russia
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11
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Hancock JT, Russell G. Downstream Signalling from Molecular Hydrogen. PLANTS (BASEL, SWITZERLAND) 2021; 10:367. [PMID: 33672953 PMCID: PMC7918658 DOI: 10.3390/plants10020367] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/09/2021] [Accepted: 02/09/2021] [Indexed: 12/23/2022]
Abstract
Molecular hydrogen (H2) is now considered part of the suite of small molecules that can control cellular activity. As such, H2 has been suggested to be used in the therapy of diseases in humans and in plant science to enhance the growth and productivity of plants. Treatments of plants may involve the creation of hydrogen-rich water (HRW), which can then be applied to the foliage or roots systems of the plants. However, the molecular action of H2 remains elusive. It has been suggested that the presence of H2 may act as an antioxidant or on the antioxidant capacity of cells, perhaps through the scavenging of hydroxyl radicals. H2 may act through influencing heme oxygenase activity or through the interaction with reactive nitrogen species. However, controversy exists around all the mechanisms suggested. Here, the downstream mechanisms in which H2 may be involved are critically reviewed, with a particular emphasis on the H2 mitigation of stress responses. Hopefully, this review will provide insight that may inform future research in this area.
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Affiliation(s)
- John T. Hancock
- Department of Applied Sciences, University of the West of England, Bristol BS16 1QY, UK;
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12
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Ratajczyk T, Buntkowsky G, Gutmann T, Fedorczyk B, Mames A, Pietrzak M, Puzio Z, Szkudlarek PG. Magnetic Resonance Signal Amplification by Reversible Exchange of Selective PyFALGEA Oligopeptide Ligands Towards Epidermal Growth Factor Receptors. Chembiochem 2020; 22:855-860. [PMID: 33063920 DOI: 10.1002/cbic.202000711] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Indexed: 12/13/2022]
Abstract
The biorelevant PyFALGEA oligopeptide ligand, which is selective towards the epidermal growth factor receptor (EGFR), has been successfully employed as a substrate in magnetic resonance signal amplification by reversible exchange (SABRE) experiments. It is demonstrated that PyFALGEA and the iridium catalyst IMes form a PyFALGEA:IMes molecular complex. The interaction between PyFALGEA:IMes and H2 results in a ternary SABRE complex. Selective 1D EXSY experiments reveal that this complex is labile, which is an essential condition for successful hyperpolarization by SABRE. Polarization transfer from parahydrogen to PyFALGEA is observed leading to significant enhancement of the 1 H NMR signals of PyFALGEA. Different iridium catalysts and peptides are inspected to discuss the influence of their molecular structures on the efficiency of hyperpolarization. It is observed that PyFALGEA oligopeptide hyperpolarization is more efficient when an iridium catalyst with a sterically less demanding NHC ligand system such as IMesBn is employed. Experiments with shorter analogues of PyFALGEA, that is, PyLGEA and PyEA, show that the bulky phenylalanine from the PyFALGEA oligopeptide causes steric hindrance in the SABRE complex, which hampers hyperpolarization with IMes. Finally, a single-scan 1 H NMR SABRE experiment of PyFALGEA with IMesBn revealed a unique pattern of NMR lines in the hydride region, which can be treated as a fingerprint of this important oligopeptide.
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Affiliation(s)
- Tomasz Ratajczyk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Gerd Buntkowsky
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Torsten Gutmann
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, 64287, Darmstadt, Germany
| | - Bartłomiej Fedorczyk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warsaw, Poland.,Biological and Chemical Research Centre, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Adam Mames
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Zuzanna Puzio
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662, Warsaw, Poland
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13
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A forty year journey: The generation and roles of NO in plants. Nitric Oxide 2019; 93:53-70. [DOI: 10.1016/j.niox.2019.09.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/28/2019] [Accepted: 09/16/2019] [Indexed: 02/07/2023]
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14
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Schmidt AB, Wörner J, Pravdivtsev A, Knecht S, Scherer H, Weber S, Hennig J, von Elverfeldt D, Hövener J. Lifetime of Parahydrogen in Aqueous Solutions and Human Blood. Chemphyschem 2019; 20:2408-2412. [PMID: 31479580 PMCID: PMC7687157 DOI: 10.1002/cphc.201900670] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/16/2019] [Indexed: 02/03/2023]
Abstract
Molecular hydrogen has unique nuclear spin properties. Its nuclear spin isomer, parahydrogen (pH2 ), was instrumental in the early days of quantum mechanics and allows to boost the NMR signal by several orders of magnitude. pH2- induced polarization (PHIP) is based on the survival of pH2 spin order in solution, yet its lifetime has not been investigated in aqueous or biological media required for in vivo applications. Herein, we report longitudinal relaxation times (T1 ) and lifetimes of pH2 ( τ P O C ) in methanol and water, with or without O2 , NaCl, rhodium-catalyst or human blood. Furthermore, we present a relaxation model that uses T1 and τ P O C for more precise theoretical predictions of the H2 spin state in PHIP experiments. All measured T1 values were in the range of 1.4-2 s and τ P O C values were of the order of 10-300 minutes. These relatively long lifetimes hold great promise for emerging in vivo implementations and applications of PHIP.
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Affiliation(s)
- Andreas B. Schmidt
- Department of Radiology, Medical Physics Albert-Ludwigs-Universität FreiburgUniversitätsklinikum FreiburgKilianstr. 5A79106FreiburgGermany.
- Department of Radiology and Neuroradiology Section Biomedical Imaging, MOIN CCUniversitätsklinikum Schleswig-Holstein, Universität KielAm Botanischen Garten 1424118KielGermany
| | - Jakob Wörner
- Institut für Physikalische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104FreiburgGermany
| | - Andrey Pravdivtsev
- Department of Radiology and Neuroradiology Section Biomedical Imaging, MOIN CCUniversitätsklinikum Schleswig-Holstein, Universität KielAm Botanischen Garten 1424118KielGermany
| | - Stephan Knecht
- Department of Radiology, Medical Physics Albert-Ludwigs-Universität FreiburgUniversitätsklinikum FreiburgKilianstr. 5A79106FreiburgGermany.
- Chemie, Arbeitskreis BuntkowskyTechnische Universität DarmstadtAlarich-Weiss-Str. 864287DarmstadtGermany
| | - Harald Scherer
- Institut für Anorganische und Analytische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104FreiburgGermany
| | - Stefan Weber
- Institut für Physikalische ChemieAlbert-Ludwigs-Universität FreiburgAlbertstr. 2179104FreiburgGermany
| | - Jürgen Hennig
- Department of Radiology, Medical Physics Albert-Ludwigs-Universität FreiburgUniversitätsklinikum FreiburgKilianstr. 5A79106FreiburgGermany.
| | - Dominik von Elverfeldt
- Department of Radiology, Medical Physics Albert-Ludwigs-Universität FreiburgUniversitätsklinikum FreiburgKilianstr. 5A79106FreiburgGermany.
| | - Jan‐Bernd Hövener
- Department of Radiology and Neuroradiology Section Biomedical Imaging, MOIN CCUniversitätsklinikum Schleswig-Holstein, Universität KielAm Botanischen Garten 1424118KielGermany
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15
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Das T, Choi JG, Oh IH. Synthesis of Highly Effective α-Fe2O3 Catalyst for the Spin Conversion of Liquid Hydrogen. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES INDIA SECTION A-PHYSICAL SCIENCES 2019. [DOI: 10.1007/s40010-019-00599-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Hancock JT, Neill SJ. Nitric Oxide: Its Generation and Interactions with Other Reactive Signaling Compounds. PLANTS (BASEL, SWITZERLAND) 2019; 8:E41. [PMID: 30759823 PMCID: PMC6409986 DOI: 10.3390/plants8020041] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 02/07/2019] [Accepted: 02/10/2019] [Indexed: 12/25/2022]
Abstract
Nitric oxide (NO) is an immensely important signaling molecule in animals and plants. It is involved in plant reproduction, development, key physiological responses such as stomatal closure, and cell death. One of the controversies of NO metabolism in plants is the identification of enzymatic sources. Although there is little doubt that nitrate reductase (NR) is involved, the identification of a nitric oxide synthase (NOS)-like enzyme remains elusive, and it is becoming increasingly clear that such a protein does not exist in higher plants, even though homologues have been found in algae. Downstream from its production, NO can have several potential actions, but none of these will be in isolation from other reactive signaling molecules which have similar chemistry to NO. Therefore, NO metabolism will take place in an environment containing reactive oxygen species (ROS), hydrogen sulfide (H₂S), glutathione, other antioxidants and within a reducing redox state. Direct reactions with NO are likely to produce new signaling molecules such as peroxynitrite and nitrosothiols, and it is probable that chemical competitions will exist which will determine the ultimate end result of signaling responses. How NO is generated in plants cells and how NO fits into this complex cellular environment needs to be understood.
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Affiliation(s)
- John T Hancock
- Department of Applied Sciences, University of the West of England, Bristol BS16 1QY, UK.
| | - Steven J Neill
- Faculty of Health and Applied Sciences, University of the West of England, Bristol BS16 1QY, UK.
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17
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Gołowicz D, Kazimierczuk K, Urbańczyk M, Ratajczyk T. Monitoring Hydrogenation Reactions using Benchtop 2D NMR with Extraordinary Sensitivity and Spectral Resolution. ChemistryOpen 2019; 8:196-200. [PMID: 30815327 PMCID: PMC6376214 DOI: 10.1002/open.201800294] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/21/2019] [Indexed: 12/02/2022] Open
Abstract
Low-field benchtop nuclear magnetic resonance (BT-NMR) spectrometers with Halbach magnets are being increasingly used in science and industry as cost-efficient tools for the monitoring of chemical reactions, including hydrogenation. However, their use of low-field magnets limits both resolution and sensitivity. In this paper, we show that it is possible to alleviate these two problems through the combination of parahydrogen-induced polarization (PHIP) and fast correlation spectroscopy with time-resolved non-uniform sampling (TR-NUS). PHIP can enhance NMR signals so that substrates are easily detectable on BT-NMR spectrometers. The interleaved acquisition of one- and two-dimensional spectra with TR-NUS provides unique insight into the consecutive moments of hydrogenation reactions, with a spectral resolution unachievable in a standard approach. We illustrate the potential of the technique with two examples: the hydrogenation of ethylphenyl propiolate and the hydrogenation of a mixture of two substrates - ethylphenyl propiolate and ethyl 2-butynoate.
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Affiliation(s)
- Dariusz Gołowicz
- Faculty of Chemistry, Biological and Chemical Research CentreUniversity of WarsawŻwirki i Wigury 10102-089WarsawPoland
- Centre of New TechnologiesUniversity of WarsawBanacha 2 C02-097WarsawPoland
| | | | - Mateusz Urbańczyk
- Centre of New TechnologiesUniversity of WarsawBanacha 2 C02-097WarsawPoland
- NMR Research UnitUniversity of Oulu90014OuluFinland
| | - Tomasz Ratajczyk
- Institute of Physical ChemistryPolish Academy of SciencesKasprzaka 44/5201-224WarsawPoland
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18
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Parrott AJ, Dallin P, Andrews J, Richardson PM, Semenova O, Halse ME, Duckett SB, Nordon A. Quantitative In Situ Monitoring of Parahydrogen Fraction Using Raman Spectroscopy. APPLIED SPECTROSCOPY 2019; 73:88-97. [PMID: 30203662 DOI: 10.1177/0003702818798644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Raman spectroscopy has been used to provide a rapid, noninvasive, and nondestructive quantification method for determining the parahydrogen fraction of hydrogen gas. The basis of the method is the measurement of the ratio of the first two rotational bands of hydrogen at 355 cm-1 and 586 cm-1 corresponding to parahydrogen and orthohydrogen, respectively. The method has been used to determine the parahydrogen content during a production process and a reaction. In the first example, the performance of an in-house liquid nitrogen cooled parahydrogen generator was monitored both at-line and on-line. The Raman measurements showed that it took several hours for the generator to reach steady state and, hence, for maximum parahydrogen production (50%) to be reached. The results obtained using Raman spectroscopy were compared to those obtained by at-line low-field nuclear magnetic resonance (NMR) spectroscopy. While the results were in good agreement, Raman analysis has several advantages over NMR for this application. The Raman method does not require a reference sample, as both spin isomers (ortho and para) of hydrogen can be directly detected, which simplifies the procedure and eliminates some sources of error. In the second example, the method was used to monitor the fast conversion of parahydrogen to orthohydrogen in situ. Here the ability to acquire Raman spectra every 30 s enabled a conversion process with a rate constant of 27.4×10-4 s-1 to be monitored. The Raman method described here represents an improvement on previously reported work, in that it can be easily applied on-line and is approximately 500 times faster. This offers the potential of an industrially compatible method for determining parahydrogen content in applications that require the storage and usage of hydrogen.
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Affiliation(s)
- Andrew J Parrott
- 1 WestCHEM, Department of Pure and Applied Chemistry and CPACT, University of Strathclyde, Glasgow, UK
| | | | | | - Peter M Richardson
- 3 Centre for Hyperpolarisation in Magnetic Resonance (CHyM), Department of Chemistry, University of York, York, UK
| | - Olga Semenova
- 3 Centre for Hyperpolarisation in Magnetic Resonance (CHyM), Department of Chemistry, University of York, York, UK
| | - Meghan E Halse
- 3 Centre for Hyperpolarisation in Magnetic Resonance (CHyM), Department of Chemistry, University of York, York, UK
| | - Simon B Duckett
- 3 Centre for Hyperpolarisation in Magnetic Resonance (CHyM), Department of Chemistry, University of York, York, UK
| | - Alison Nordon
- 1 WestCHEM, Department of Pure and Applied Chemistry and CPACT, University of Strathclyde, Glasgow, UK
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19
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Emondts M, Colell JFP, Blümich B, Schleker PPM. Polarization transfer efficiency in PHIP experiments. Phys Chem Chem Phys 2018; 19:21933-21937. [PMID: 28808726 DOI: 10.1039/c7cp04296e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Parahydrogen induced polarization (PHIP) is a hyperpolarization method for NMR signal enhancement with applications in spectroscopy and imaging. Although parahydrogen can be easily enriched up to nearly 95%, the polarization detected on the hydrogenated substrate is substantially lower, where numerous loss mechanisms between the start of the hydrogenation reaction and detection affect polarization levels. The quality of PHIP systems is commonly determined by stating either the polarization degree or the enhancement factor of the product at the time of detection. In this study, we present a method that allows the distinction of polarization loss due to both the catalytic cycle and T1 relaxation of the formed product prior to detection. We determine the influence of homogeneous catalysts and define a rigorous measure of the polarization transfer efficiency (PTE). Our results show that the PTE strongly depends on the concentration of all components and the chemical structure of the catalyst as well as on the magnetic field of detection.
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Affiliation(s)
- M Emondts
- RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Worringer Weg 1, 52074 Aachen, Germany.
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20
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Kiryutin AS, Sauer G, Hadjiali S, Yurkovskaya AV, Breitzke H, Buntkowsky G. A highly versatile automatized setup for quantitative measurements of PHIP enhancements. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 285:26-36. [PMID: 29073504 DOI: 10.1016/j.jmr.2017.10.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/12/2017] [Accepted: 10/14/2017] [Indexed: 05/02/2023]
Abstract
The design and application of a versatile and inexpensive experimental extension to NMR spectrometers is described that allows to carry out highly reproducible PHIP experiments directly in the NMR sample tube, i.e. under PASADENA condition, followed by the detection of the NMR spectra of hyperpolarized products with high spectral resolution. Employing this high resolution it is feasible to study kinetic processes in the solution with high accuracy. As a practical example the dissolution of hydrogen gas in the liquid and the PHIP kinetics during the hydrogenation reaction of Fmoc-O-propargyl-l-tyrosine in acetone-d6 are monitored. The timing of the setup is fully controlled by the pulse-programmer of the NMR spectrometer. By flushing with an inert gas it is possible to efficiently quench the hydrogenation reaction in a controlled fashion and to detect the relaxation of hyperpolarization without a background reaction. The proposed design makes it possible to carry out PHIP experiments in an automatic mode and reliably determine the enhancement of polarized signals.
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Affiliation(s)
- Alexey S Kiryutin
- International Tomography Center, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Grit Sauer
- Technische Universität Darmstadt, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, Darmstadt 64287, Germany
| | - Sara Hadjiali
- Technische Universität Darmstadt, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, Darmstadt 64287, Germany
| | - Alexandra V Yurkovskaya
- International Tomography Center, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Hergen Breitzke
- Technische Universität Darmstadt, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, Darmstadt 64287, Germany
| | - Gerd Buntkowsky
- Technische Universität Darmstadt, Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, Darmstadt 64287, Germany.
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21
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Terenzi C, Bouguet-Bonnet S, Canet D. Direct 1H NMR evidence of spin-rotation coupling as a source of para → ortho-H 2 conversion in diamagnetic solvents. J Chem Phys 2017; 146:154203. [PMID: 28433034 DOI: 10.1063/1.4980079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
At ambient temperature, conversion from 100% enriched para-hydrogen (p-H2; singlet state) to ortho-hydrogen (o-H2; triplet state) leads necessarily to the thermodynamic equilibrium proportions: 75% of o-H2 and 25% of p-H2. When p-H2 is dissolved in a diamagnetic organic solvent, conversion is very slow and can be considered as arising from nuclear spin relaxation phenomena. A first relaxation mechanism, specific to the singlet state and involving a combination of auto-correlation and cross correlation spectral densities, can be retained: randomly fluctuating magnetic fields due to inter-molecular dipolar interactions. We demonstrate here that (i) this dipolar mechanism is not sufficient for accounting for the para→ortho conversion rate, (ii) spin-rotation interaction, an intra-molecular mechanism, behaves similarly to random-field interaction and, thus, may be involved in the singlet relaxation rate. Also, as the para→ortho conversion is monitored by proton nuclear magnetic resonance (NMR) of dissolved o-H2 (p-H2 is NMR-silent), one has to account for H2 exchange between the liquid phase and the gas phase within the NMR tube, as well as for dissolution effects. Experimental evidence of the above statements is brought here in the case of two organic solvents: acetone-d6 and carbon disulfide. The observed temperature dependence of the para→ortho conversion rate shows that spin-rotation can be the dominant contribution to the p-H2 relaxation rate in the absence of tangible dipolar interactions. Our findings shed new light on the "mysterious" mechanism of the para→ortho conversion which has been searched for several decades.
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Affiliation(s)
- Camilla Terenzi
- Université de Lorraine, CRM2, UMR 7036, Vandæuvre-lès-Nancy F-54506, France
| | | | - Daniel Canet
- Université de Lorraine, IJB, FR 2843, Vandæuvre-lès-Nancy F-54506, France
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22
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Hartl M, Gillis RC, Daemen L, Olds DP, Page K, Carlson S, Cheng Y, Hügle T, Iverson EB, Ramirez-Cuesta AJ, Lee Y, Muhrer G. Hydrogen adsorption on two catalysts for the ortho- to parahydrogen conversion: Cr-doped silica and ferric oxide gel. Phys Chem Chem Phys 2016; 18:17281-93. [DOI: 10.1039/c6cp01154c] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Interaction of molecular hydrogen with the surface of the ortho–para conversion catalyst.
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Affiliation(s)
| | | | - Luke Daemen
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Daniel P. Olds
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Katherine Page
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | | | - Yongqiang Cheng
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Thomas Hügle
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
| | - Erik B. Iverson
- Spallation Neutron Source
- Oak Ridge National Laboratory
- Oak Ridge
- USA
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23
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Pravdivtsev AN, Ivanov KL, Yurkovskaya AV, Petrov PA, Limbach HH, Kaptein R, Vieth HM. Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 261:73-82. [PMID: 26529205 DOI: 10.1016/j.jmr.2015.10.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/05/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the (1)H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes. We studied two Ir-complexes and have shown that the presence of a (31)P atom in the SABRE complex doubles the number of LACs and, consequently, the number of peaks in the SABRE field dependence. Interestingly, the polarization of SABRE substrates is always accompanied by the para-to-ortho conversion in dihydride species that results in enhancement of the NMR signal of free (H2) and catalyst-bound H2 (Ir-HH). The field dependences of hyperpolarized H2 and Ir-HH by means of SABRE are studied here, for the first time, in detail. The field dependences depend on the chemical shifts and coupling constants of Ir-HH, in which the polarization transfer takes place. A negative coupling constant of -7Hz between the two chemically equivalent but magnetically inequivalent hydride nuclei is determined, which indicates that Ir-HH is a dihydride with an HH distance larger than 2Å. Finally, the field dependence of SABRE at high fields as found earlier has been investigated and attributed to polarization transfer to the substrate by cross-relaxation. The present study provides further evidence for the key role of LACs in the formation of SABRE-derived polarization. Understanding the spin dynamics behind the SABRE method opens the way to optimizing its performance and overcoming the main limitation of NMR, its notoriously low sensitivity.
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Affiliation(s)
- Andrey N Pravdivtsev
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Konstantin L Ivanov
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Alexandra V Yurkovskaya
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Pavel A Petrov
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia; Nikolaev Institute of Inorganic Chemistry SB RAS, Acad. Lavrentiev Ave., 3, Novosibirsk 630090, Russia
| | - Hans-Heinrich Limbach
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany
| | - Robert Kaptein
- Utrecht University, Bijvoet Center, Padualaan 8, NL-3584 CH Utrecht, The Netherlands
| | - Hans-Martin Vieth
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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24
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Terenzi C, Bouguet-Bonnet S, Canet D. Electron Spin Polarization Transfer to ortho-H2 by Interaction of para-H2 with Paramagnetic Species: A Key to a Novel para → ortho Conversion Mechanism. J Phys Chem Lett 2015; 6:1611-1615. [PMID: 26263322 DOI: 10.1021/acs.jpclett.5b00518] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report that at ambient temperature and with 100% enriched para-hydrogen (p-H2) dissolved in organic solvents, paramagnetic spin catalysis of para → ortho hydrogen conversion is accompanied at the onset by a negative ortho-hydrogen (o-H2) proton NMR signal. This novel finding indicates an electron spin polarization transfer, and we show here that this can only occur if the H2 molecule is dissociated upon its transient adsorption by the paramagnetic catalyst. Following desorption, o-H2 is created until the thermodynamic equilibrium is reached. A simple theory confirms that in the presence of a static magnetic field, the hyperfine coupling between unpaired electrons and nuclear spins is responsible for the observed polarization transfer. Owing to the negative electron gyromagnetic ratio, this explains the experimental results and ascertains an as yet unexplored mechanism for para → ortho conversion. Finally, we show that the recovery of o-H2 magnetization toward equilibrium can be simply modeled, leading to the para → ortho conversion rate.
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Affiliation(s)
- Camilla Terenzi
- †Université de Lorraine, CRM2, UMR 7036, Vandœuvre-lès-Nancy F-54506, France
- ‡CNRS, CRM2, UMR 7036, Vandœuvre-lès-Nancy F-54506, France
| | - Sabine Bouguet-Bonnet
- †Université de Lorraine, CRM2, UMR 7036, Vandœuvre-lès-Nancy F-54506, France
- ‡CNRS, CRM2, UMR 7036, Vandœuvre-lès-Nancy F-54506, France
| | - Daniel Canet
- §Université de Lorraine, IJB, FR 2843, Vandœuvre-lès-Nancy F-54506, France
- ∥CNRS, IJB, FR 2843, Vandœuvre-lès-Nancy F-54506, France
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25
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Barskiy DA, Salnikov OG, Kovtunov KV, Koptyug IV. NMR Signal Enhancement for Hyperpolarized Fluids Continuously Generated in Hydrogenation Reactions with Parahydrogen. J Phys Chem A 2015; 119:996-1006. [DOI: 10.1021/jp510572d] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Danila A. Barskiy
- International
Tomography Center, Siberian Branch of the Russian Academy of Sciences, 3A Institutskaya Street, Novosibirsk, Russia, 630090
- Novosibirsk State University, 2 Pirogova
Street, Novosibirsk, Russia, 630090
| | - Oleg G. Salnikov
- International
Tomography Center, Siberian Branch of the Russian Academy of Sciences, 3A Institutskaya Street, Novosibirsk, Russia, 630090
- Novosibirsk State University, 2 Pirogova
Street, Novosibirsk, Russia, 630090
| | - Kirill V. Kovtunov
- International
Tomography Center, Siberian Branch of the Russian Academy of Sciences, 3A Institutskaya Street, Novosibirsk, Russia, 630090
- Novosibirsk State University, 2 Pirogova
Street, Novosibirsk, Russia, 630090
| | - Igor V. Koptyug
- International
Tomography Center, Siberian Branch of the Russian Academy of Sciences, 3A Institutskaya Street, Novosibirsk, Russia, 630090
- Novosibirsk State University, 2 Pirogova
Street, Novosibirsk, Russia, 630090
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26
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Hama T, Watanabe N. Surface Processes on Interstellar Amorphous Solid Water: Adsorption, Diffusion, Tunneling Reactions, and Nuclear-Spin Conversion. Chem Rev 2013; 113:8783-839. [DOI: 10.1021/cr4000978] [Citation(s) in RCA: 211] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tetsuya Hama
- Institute of Low Temperature
Science, Hokkaido University, N19W8 Kita-ku, Sapporo, Hokkaido 060-0819, Japan
| | - Naoki Watanabe
- Institute of Low Temperature
Science, Hokkaido University, N19W8 Kita-ku, Sapporo, Hokkaido 060-0819, Japan
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27
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Gutmann T, del Rosal I, Chaudret B, Poteau R, Limbach HH, Buntkowsky G. From Molecular Complexes to Complex Metallic Nanostructures-2H Solid-State NMR Studies of Ruthenium-Containing Hydrogenation Catalysts. Chemphyschem 2013; 14:3026-33. [DOI: 10.1002/cphc.201300200] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 11/08/2022]
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28
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Hövener JB, Bär S, Leupold J, Jenne K, Leibfritz D, Hennig J, Duckett SB, von Elverfeldt D. A continuous-flow, high-throughput, high-pressure parahydrogen converter for hyperpolarization in a clinical setting. NMR IN BIOMEDICINE 2013; 26:124-131. [PMID: 22833391 DOI: 10.1002/nbm.2827] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 05/10/2012] [Accepted: 05/12/2012] [Indexed: 06/01/2023]
Abstract
Pure parahydrogen (pH(2) ) is the prerequisite for optimal pH(2) -based hyperpolarization experiments, promising approaches to access the hidden orders of magnitude of MR signals. pH(2) production on-site in medical research centers is vital for the proliferation of these technologies in the life sciences. However, previously suggested designs do not meet our requirements for safety or production performance (flow rate, pressure or enrichment). In this article, we present the safety concept, design and installation of a pH(2) converter, operated in a clinical setting. The apparatus produces a continuous flow of four standard liters per minute of ≈98% enriched pH(2) at a pressure maximum of 50 bar. The entire production cycle, including cleaning and cooling to 25 K, takes less than 5 h, only ≈45 min of which are required for actual pH(2) conversion. A fast and simple quantification procedure is described. The lifetimes of pH(2) in a glass vial and aluminum storage cylinder are measured to be T(1C) (glass vial) =822 ± 29 min and T(1C) (Al cylinder) =129 ± 36 days, thus providing sufficiently long storage intervals and allowing the application of pH(2) on demand. A dependence of line width on pH(2) enrichment is observed. As examples, (1) H hyperpolarization of pyridine and (13) C hyperpolarization of hydroxyethylpropionate are presented.
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Affiliation(s)
- Jan-Bernd Hövener
- Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany.
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29
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Körner M, Sauer G, Heil A, Nasu D, Empting M, Tietze D, Voigt S, Weidler H, Gutmann T, Avrutina O, Kolmar H, Ratajczyk T, Buntkowsky G. PHIP-label: parahydrogen-induced polarization in propargylglycine-containing synthetic oligopeptides. Chem Commun (Camb) 2013; 49:7839-41. [DOI: 10.1039/c3cc43978j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Gutmann T, Ratajczyk T, Xu Y, Breitzke H, Grünberg A, Dillenberger S, Bommerich U, Trantzschel T, Bernarding J, Buntkowsky G. Understanding the leaching properties of heterogenized catalysts: a combined solid-state and PHIP NMR study. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2010; 38:90-96. [PMID: 21435842 DOI: 10.1016/j.ssnmr.2011.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/01/2011] [Accepted: 03/02/2011] [Indexed: 05/30/2023]
Abstract
Para-hydrogen induced polarization (PHIP) NMR in solution, combined with solid-state NMR, can be efficiently employed for the highly sensitive in-situ detection of the leaching properties of immobilized catalysts. The knowledge of this property is important for possible applications of PHIP experiments in medicine, biology or industry, where leached catalysts poison the solution of hyperpolarized products. As experimental example Wilkinson's catalyst RhCl(PPh(3))(3) (1) immobilized on mesoporous silica is chosen. As model reaction the hydrogenation of styrene in solvents with different polarities (methanol-d(4), acetone-d(6) and benzene-d(6)) is used. A (31)P solid-state MAS-NMR study reveals that there are two different species of catalysts on the silica, namely coordinatively bound catalysts and physisorbed catalyst. Only the second species exhibits substantial leaching, which is visible in a strong PHIP enhancement of the reaction product.
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Affiliation(s)
- Torsten Gutmann
- Institute of Physical Chemistry, Technical University Darmstadt, Petersenstrasse 22, D-64287 Darmstadt, Germany
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31
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Limbach HH, Schowen KB, Schowen RL. Heavy atom motions and tunneling in hydrogen transfer reactions: the importance of the pre-tunneling state. J PHYS ORG CHEM 2010. [DOI: 10.1002/poc.1663] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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32
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Buntkowsky G, Limbach HH, Walaszek B, Adamczyk A, Xu Y, Breitzke H, Schweitzer A, Gutmann T, Wächtler M, Amadeu N, Tietze D, Chaudret B. Mechanisms of Dipolar Ortho/Para-H2O Conversion in Ice. Z PHYS CHEM 2009. [DOI: 10.1524/zpch.2008.5359] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
In this paper a possible explanation for an unexpected ortho/para-water ratio in the gas clouds of comets is given. The description is based on the quantum-mechanical density matrix formalism and the spin temperature concept. Only the nuclear spin system is treated quantum-mechanically. Employing the model of a four spin system, created by two nearest neighbour water molecules, spin eigenstates and their dynamics under the influence of their mutual dipolar interactions are studied. It is shown that a fast conversion between ortho- and para-states occurs on a msec time scale, caused by the intermolecular homonuclear magnetic dipolar interaction. Moreover the spin eigenstates of water in an ice crystal are determined by magnetic dipolar interactions and are not given by normal ortho- and para-H2O states of gaseous water. As a result of this the spin temperature of gaseous water evaporated from ice depends strongly on its evaporation history and the ortho/para-ratio of water molecules are only an indirect measure of the temperature of ice crystals from where they descend. This result could explain the unexpected experimentally observed ortho/para-ratios in the clouds of comets.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Bruno Chaudret
- Laboratoire de Chimie de Doordination du CNRS, Toulouse Cedex 04, Frankreich
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33
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Walaszek B, Yeping X, Adamczyk A, Breitzke H, Pelzer K, Limbach HH, Huang J, Li H, Buntkowsky G. 2H-solid-state-NMR study of hydrogen adsorbed on catalytically active ruthenium coated mesoporous silica materials. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2009; 35:164-171. [PMID: 19359146 DOI: 10.1016/j.ssnmr.2009.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 02/17/2009] [Accepted: 02/26/2009] [Indexed: 05/27/2023]
Abstract
(2)H solid-state NMR measurements were performed on three samples of ruthenium nanoparticles synthesized inside two different kinds of mesoporous silica, namely SBA-3 silica materials and SBA-15 functionalized with -COOH groups and loaded with deuterium gas. The line-shape analyses of the spectra reveal the different deuteron species. In all samples a strong -OD signal is found, which shows the catalytic activity of the metal, which activates the D-D bond and deuterates the -SiOH groups through the gas phase, corroborating their usability as catalysts for hydrogenation reactions. At room temperature the mobility of the -Si-OD groups depends on the sample preparation. In addition to the -Si-OD deuterons, the presence of different types of deuterons bound to the metal is revealed. The singly coordinated -Ru-D species exhibit several different quadrupolar couplings, which indicate the presence of several non-equivalent binding sites with differing binding strength. In addition to the dissociated hydrogen species there is also a dihydrogen species -Ru-D(2), which is attributed to defect sites on the surface. It exhibits a fast rotational dynamics at all temperatures. Finally there are also indications of three-fold coordinated surface deuterons and octahedrally coordinated deuterons inside the metal.
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Affiliation(s)
- Bernadeta Walaszek
- Institut für Physikalische und Theoretische Chemie, Freie Universität Berlin, Berlin, Germany
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34
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Gutmann T, Sellin M, Breitzke H, Stark A, Buntkowsky G. Para-hydrogen induced polarization in homogeneous phase—an example of how ionic liquids affect homogenization and thus activation of catalysts. Phys Chem Chem Phys 2009; 11:9170-5. [DOI: 10.1039/b908198d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Sartori E, Ruzzi M, Lawler RG, Turro NJ. Nitroxide paramagnet-induced para-ortho conversion and nuclear spin relaxation of H2 in organic solvents. J Am Chem Soc 2008; 130:12752-6. [PMID: 18712869 DOI: 10.1021/ja8037195] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The kinetics of para-ortho conversion and nuclear spin relaxation of H 2 in chloroform- d 1 were investigated in the presence of nitroxides as paramagnetic catalysts. The back conversion from para-hydrogen ( p-H 2) to ortho-hydrogen ( o-H 2) was followed by NMR by recording the increase in the intensity of the signal of o-H 2 at regular intervals of time. The nitroxides proved to be hundreds of times more effective at inducing relaxation among the spin levels of o-H 2 than they are in bringing about transitions between p-H 2 and the levels of o-H 2. The value of the encounter distance d between H 2 and the paramagnetic molecule, calculated from the experimental bimolecular conversion rate constant k 0, using the Wigner theory of para-ortho conversion, agrees perfectly with that calculated from the experimental relaxivity R 1 using the force free diffusion theory of spin-lattice relaxation.
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Affiliation(s)
- Elena Sartori
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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36
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Adamczyk A, Xu Y, Walaszek B, Roelofs F, Pery T, Pelzer K, Philippot K, Chaudret B, Limbach HH, Breitzke H, Buntkowsky G. Solid State and Gas Phase NMR Studies of Immobilized Catalysts and Catalytic Active Nanoparticles. Top Catal 2008. [DOI: 10.1007/s11244-008-9054-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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37
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Morré DJ, Orczyk J, Hignite H, Kim C. Regular oscillatory behavior of aqueous solutions of CuII salts related to effects on equilibrium dynamics of ortho/para hydrogen spin isomers of water. J Inorg Biochem 2007; 102:260-7. [PMID: 17936362 DOI: 10.1016/j.jinorgbio.2007.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 08/03/2007] [Accepted: 08/23/2007] [Indexed: 10/22/2022]
Abstract
Cell surface and growth-related NADH oxidases with protein disulfide-thiol interchange activity, ECTO-NOX, exhibit copper-dependent, clock-related, temperature-independent and entrainable patterns of regular oscillations in the rate of oxidation of NAD(P)H as do aqueous solutions of copper salts. Because of time scale similarities, a basis for the oscillatory patterns in nuclear spin orientations of the hydrogen atoms of the copper-associated water was sought. Extended X-ray absorption fine structure (EXAFS) measurements at 9302 eV on pure water were periodic with a ca. 3.5 min peak to peak separation. Decomposition fits revealed 5 unequally spaced maxima similar to those observed previously for Cu(II)Cl(2) to generate a period length of about 18 min. With D(2)O, the period length was proportionately increased by 30% to 24 min. The redox potential of water and of D(2)O also oscillated with 18 and 24 min period lengths, respectively. Measurements in the middle infrared spectral region above a water sample surface revealed apparent oscillations in the two alternative orientations of the nuclear spins (ortho and para) of the hydrogen atoms of the water or D(2)O with 5 unequally spaced maxima and respective period lengths of 18 and 24 min. Thus, the time keeping oscillations of ECTO-NOX proteins appear to reflect the equilibrium dynamics of ortho-para hydrogen atom spin ratios of water where the presence of metal cations such as Cu(II) in solution determine period length.
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Affiliation(s)
- D J Morré
- Department of Medicinal Chemistry and Molecular Pharmacology, Hansen Life Sciences Research Building, Purdue University, 201 S. University Street, West Lafayette, IN 47907-2064, United States.
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38
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Quantum separation of para- and ortho-fulvene with coherent light: The influence of the conical intersection. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.05.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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39
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Koptyug IV, Kovtunov KV, Burt SR, Anwar MS, Hilty C, Han SI, Pines A, Sagdeev RZ. para-Hydrogen-Induced Polarization in Heterogeneous Hydrogenation Reactions. J Am Chem Soc 2007; 129:5580-6. [PMID: 17408268 DOI: 10.1021/ja068653o] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate the creation and observation of para-hydrogen-induced polarization in heterogeneous hydrogenation reactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on either modified silica gel or a polymer, is shown to hydrogenate styrene into ethylbenzene and to produce enhanced spin polarizations, observed through NMR, when the reaction was performed with H2 gas enriched in the para spin isomer. Furthermore, gaseous phase para-hydrogenation of propylene to propane with two catalysts, the Wilkinson's catalyst supported on modified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene; sulfos = -O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstrates heterogeneous catalytic conversion resulting in large spin polarizations. These experiments serve as a direct verification of the mechanism of heterogeneous hydrogenation reactions involving immobilized metal complexes and can be potentially developed into a practical tool for producing catalyst-free fluids with highly polarized nuclear spins for a broad range of hyperpolarized NMR and MRI applications.
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Affiliation(s)
- Igor V Koptyug
- International Tomography Center, 3A Institutskaya Street, Novosibirsk 630090, Russia.
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40
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Deeb O, Leibscher M, Manz J, von Muellern W, Seideman T. Toward Separation of Nuclear Spin Isomers with Coherent Light. Chemphyschem 2007; 8:322-8. [PMID: 17183525 DOI: 10.1002/cphc.200600543] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We propose an approach for separating nuclear spin isomers with coherent light and illustrate it by numerical calculations using fulvene as a model system. The scheme employs the equivalence of torsion and interchange of equivalent H-atoms in a class of molecules of which fulvene is a simple example. The exchange symmetry couples with the rotational symmetry to produce a spatial distinction between the two photo-excited nuclear spin isomers, and wavepacket interferometry is applied to separate the species.
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Affiliation(s)
- Omar Deeb
- Department of Chemistry and Chemical Technology, Al-Quds University, P.O.Box 20002 Jerusalem (Palestinian Authority)
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