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Gizatullin B, Gafurov M, Murzakhanov F, Vakhin A, Mattea C, Stapf S. Molecular Dynamics and Proton Hyperpolarization via Synthetic and Crude Oil Porphyrin Complexes in Solid and Solution States. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6783-6791. [PMID: 34041909 DOI: 10.1021/acs.langmuir.1c00882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The use of vanadyl porphyrins either in synthetic compounds or naturally occurring in asphaltenes is investigated as a source of proton hyperpolarization via dynamic nuclear polarization (DNP) in nuclear magnetic resonance (NMR) experiments. The features of dynamics and location of the vanadyl VO2+ complex in aggregates within the oil asphaltene molecules are studied by means of DNP, electron paramagnetic resonance (EPR), and NMR field cycling relaxometry. Both the solid effect and Overhauser DNP were observed for the asphaltene solution in benzene, as well as in the solution and solid states for synthetic compounds. By comparison with a solution of synthetic vanadyl porphyrins, it is shown that vanadyl porphyrins in asphaltene aggregates are localized outside of the interface of the asphaltene aggregates and more exposed to the maltene molecules than "free" carbon-centered radicals associated with the core of asphaltene molecules. The perceptible contribution of scalar interaction is observed in solutions for both synthetic and asphaltene vanadyl porphyrins.
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Affiliation(s)
- Bulat Gizatullin
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Marat Gafurov
- Kazan Federal University, Kremlevskaya, 18, Kazan 420008, Russia
| | | | - Alexey Vakhin
- Kazan Federal University, Kremlevskaya, 18, Kazan 420008, Russia
| | - Carlos Mattea
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Siegfried Stapf
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
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Neudert O, Mattea C, Stapf S. Molecular dynamics-based selectivity for Fast-Field-Cycling relaxometry by Overhauser and solid effect dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 276:113-121. [PMID: 28183023 DOI: 10.1016/j.jmr.2017.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 06/06/2023]
Abstract
In the last decade nuclear spin hyperpolarization methods, especially Dynamic Nuclear Polarization (DNP), have provided unprecedented possibilities for various NMR techniques by increasing the sensitivity by several orders of magnitude. Recently, in-situ DNP-enhanced Fast Field Cycling (FFC) relaxometry was shown to provide appreciable NMR signal enhancements in liquids and viscous systems. In this work, a measurement protocol for DNP-enhanced NMR studies is introduced which enables the selective detection of nuclear spin hyperpolarized by either Overhauser effect or solid effect DNP. Based on field-cycled DNP and relaxation studies it is shown that these methods allow for the independent measurement of polymer and solvent nuclear spins in a concentrated solution of high molecular weight polybutadiene in benzene doped with α,γ-bisdiphenylene-β-phenylallyl radical. Appreciable NMR signal enhancements of about 10-fold were obtained for both constituents. Moreover, qualitative information about the dynamics of the radical and solvent was obtained. Selective DNP-enhanced FFC relaxometry is applied for the measurement of the 1H nuclear magnetic relaxation dispersion of both constituents with improved precision. The introduced method is expected to greatly facilitate NMR studies of complex systems with multiple overlapping signal contributions that cannot be distinguished by standard methods.
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Affiliation(s)
- Oliver Neudert
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, 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
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Goslar J, Hoffmann SK, Lijewski S. Dynamics of 4-oxo-TEMPO-d16-(15)N nitroxide-propylene glycol system studied by ESR and ESE in liquid and glassy state in temperature range 10-295K. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:162-175. [PMID: 27323281 DOI: 10.1016/j.jmr.2016.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
ESR spectra and electron spin relaxation of nitroxide radical in 4-oxo-TEMPO-d16-(15)N in propylene glycol were studied at X-band in the temperature range 10-295K. The spin-lattice relaxation in the liquid viscous state determined from the resonance line shape is governed by three mechanisms occurring during isotropic molecular reorientations. In the glassy state below 200K the spin-lattice relaxation, phase relaxation and electron spin echo envelope modulations (ESEEM) were studied by pulse spin echo technique using 2-pulse and 3-pulse induced signals. Electron spin-lattice relaxation is governed by a single non-phonon relaxation process produced by localized oscillators of energy 76cm(-1). Electron spin dephasing is dominated by a molecular motion producing a resonance-type peak in the temperature dependence of the dephasing rate around 120K. The origin of the peak is discussed and a simple method for the peak shape analysis is proposed, which gives the activation energy of a thermally activated motion Ea=7.8kJ/mol and correlation time τ0=10(-8)s. The spin echo amplitude is strongly modulated and FT spectrum contains a doublet of lines centered around the (2)D nuclei Zeeman frequency. The splitting into the doublet is discussed as due to a weak hyperfine coupling of nitroxide unpaired electron with deuterium of reorienting CD3 groups.
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Affiliation(s)
- Janina Goslar
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
| | - Stanislaw K Hoffmann
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland.
| | - Stefan Lijewski
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
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Kruk D, Korpała A, Taheri SM, Kozłowski A, Förster S, Rössler EA. 1H relaxation enhancement induced by nanoparticles in solutions: Influence of magnetic properties and diffusion. J Chem Phys 2014; 140:174504. [DOI: 10.1063/1.4871461] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Kruk D, Hoffmann SK, Goslar J, Lijewski S, Kubica-Misztal A, Korpała A, Oglodek I, Kowalewski J, Rössler EA, Moscicki J. ESR lineshape and 1H spin-lattice relaxation dispersion in propylene glycol solutions of nitroxide radicals--joint analysis. J Chem Phys 2013; 139:244502. [PMID: 24387377 DOI: 10.1063/1.4850635] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Electron Spin Resonance (ESR) spectroscopy and Nuclear Magnetic Relaxation Dispersion (NMRD) experiments are reported for propylene glycol solutions of the nitroxide radical: 4-oxo-TEMPO-d16 containing (15)N and (14)N isotopes. The NMRD experiments refer to (1)H spin-lattice relaxation measurements in a broad frequency range (10 kHz-20 MHz). A joint analysis of the ESR and NMRD data is performed. The ESR lineshapes give access to the nitrogen hyperfine tensor components and the rotational correlation time of the paramagnetic molecule. The NMRD data are interpreted in terms of the theory of paramagnetic relaxation enhancement in solutions of nitroxide radicals, recently presented by Kruk et al. [J. Chem. Phys. 138, 124506 (2013)]. The theory includes the effect of the electron spin relaxation on the (1)H relaxation of the solvent. The (1)H relaxation is caused by dipole-dipole interactions between the electron spin of the radical and the proton spins of the solvent molecules. These interactions are modulated by three dynamic processes: relative translational dynamics of the involved molecules, molecular rotation, and electron spin relaxation. The sensitivity to rotation originates from the non-central positions of the interacting spin in the molecules. The electronic relaxation is assumed to stem from the electron spin-nitrogen spin hyperfine coupling, modulated by rotation of the radical molecule. For the interpretation of the NMRD data, we use the nitrogen hyperfine coupling tensor obtained from ESR and fit the other relevant parameters. The consistency of the unified analysis of ESR and NMRD, evaluated by the agreement between the rotational correlation times obtained from ESR and NMRD, respectively, and the agreement of the translation diffusion coefficients with literature values obtained for pure propylene glycol, is demonstrated to be satisfactory.
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Affiliation(s)
- D Kruk
- University of Warmia & Mazury in Olsztyn, Faculty of Mathematics & Computer Science, Sloneczna 54, PL-10710 Olsztyn, Poland
| | - S K Hoffmann
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
| | - J Goslar
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
| | - S Lijewski
- Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
| | - A Kubica-Misztal
- Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - A Korpała
- Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - I Oglodek
- Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
| | - J Kowalewski
- Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, S-106 91 Stockholm, Sweden
| | - E A Rössler
- Universität Bayreuth, Experimentalphysik II, 95440 Bayreuth, Germany
| | - J Moscicki
- Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland
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