1
|
Caracciolo F, Paioni AL, Filibian M, Melone L, Carretta P. Proton and Carbon-13 Dynamic Nuclear Polarization of Methylated β-Cyclodextrins. J Phys Chem B 2018; 122:1836-1845. [PMID: 29350528 DOI: 10.1021/acs.jpcb.7b11950] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
1H and 13C dynamic nuclear polarizations have been studied in 13C-enriched β-cyclodextrins doped with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl free radical. 1H and 13C polarizations raised above 7.5 and 7%, respectively, and for both nuclear species, the transfer of polarization from the electron spins appears to be consistent with a thermal mixing scenario for a concentration of 9 13C nuclei per molecule. When the concentration is increased to 21 13C nuclei per molecule, a decrease in the spin-lattice relaxation and polarization buildup rates is observed. This reduction is associated with the bottleneck effect induced by the decrease in the number of electron spins per nucleus when both the nuclear spin-lattice relaxation and the polarization occur through the electron non-Zeeman reservoir. 13C nuclear spin-lattice relaxation has been studied in the 1.8-340 K range, and the effects of internal molecular motions and of the free radicals on the relaxation are discussed. 13C hyperpolarization performances and room-temperature spin-lattice relaxation times show that these are promising materials for future biomedical applications.
Collapse
Affiliation(s)
| | - Alessandra Lucini Paioni
- Department of Physics, University of Pavia , 27100 Pavia, Italy.,NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Marta Filibian
- Department of Physics, University of Pavia , 27100 Pavia, Italy
| | - Lucio Melone
- Department of Chemistry, Materials, and Chemical Engineering G. Natta, Politecnico di Milano , 20133 Milano, Italy
| | - Pietro Carretta
- Department of Physics, University of Pavia , 27100 Pavia, Italy
| |
Collapse
|
2
|
Organic-inorganic hybrid crystals, (2,4,6-CH3PyH)3Sb2Cl9 and (2,4,6-CH3PyH)3Bi2Cl9. Crystal structure characterization and tunneling of CH3 groups studied by 1H NMR and neutron spectroscopy. Polyhedron 2018. [DOI: 10.1016/j.poly.2017.10.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
3
|
Beckmann PA, Rheingold AL. 1H and 19F spin-lattice relaxation and CH3 or CF3 reorientation in molecular solids containing both H and F atoms. J Chem Phys 2016; 144:154308. [DOI: 10.1063/1.4944981] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
4
|
Beckmann PA, Moore CE, Rheingold AL. Methyl and t-butyl group rotation in a molecular solid: 1H NMR spin-lattice relaxation and X-ray diffraction. Phys Chem Chem Phys 2016; 18:1720-6. [DOI: 10.1039/c5cp04994f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report solid state 1H nuclear magnetic resonance spin-lattice relaxation experiments and X-ray diffractometry in 2-t-butyldimethylsilyloxy-6-bromonaphthalene.
Collapse
Affiliation(s)
| | - Curtis E. Moore
- Department of Chemistry and Biochemistry
- University of California
- La Jolla
- USA
| | | |
Collapse
|
5
|
Bernatowicz P, Shkurenko A, Osior A, Kamieński B, Szymański S. A quantum mechanical alternative to the Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids. Phys Chem Chem Phys 2015; 17:28866-78. [PMID: 26451661 DOI: 10.1039/c5cp04924e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The theory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups have recently been given a consistent quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate (i.e., coherence-damping) processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in the condensed phase can retain quantum character over much broader temperature range than is commonly thought.
Collapse
Affiliation(s)
- Piotr Bernatowicz
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - Aleksander Shkurenko
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland. and Functional Materials Design, Discovery and Development Research Group (FMD3), Advanced Membranes and Porous Materials Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Agnieszka Osior
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - Bohdan Kamieński
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - Sławomir Szymański
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| |
Collapse
|
6
|
Beckmann PA. Nonexponential (1)H spin-lattice relaxation and methyl group rotation in molecular solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 71:91-95. [PMID: 26256302 DOI: 10.1016/j.ssnmr.2015.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/14/2015] [Indexed: 06/04/2023]
Abstract
We report a quantitative measure of the nonexponential (1)H spin-lattice relaxation resulting from methyl group (CH3) rotation in six polycrystalline van der Waals solids. We briefly review the subject in general to put the report in context. We then summarize several significant issues to consider when reporting (1)H or (19)F spin-lattice relaxation measurements when the relaxation is resulting from the rotation of a CH3 or CF3 group in a molecular solid.
Collapse
Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
| |
Collapse
|
7
|
Molecular flexibility and structural instabilities in crystalline l-methionine. Biophys Chem 2013; 180-181:76-85. [PMID: 23886538 DOI: 10.1016/j.bpc.2013.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/14/2013] [Accepted: 06/14/2013] [Indexed: 11/22/2022]
Abstract
We have investigated the dynamics in polycrystalline samples of l-methionine related to the structural transition at about 307K by incoherent inelastic and quasielastic neutron scattering, X-ray powder diffraction as well as ab-initio calculations. l-Methionine is a sulfur amino acid which can be considered a derivative of alanine with the alanine R-group CH3 exchanged by CH3S(CH2)2. Using X-ray powder diffraction we have observed at ~190K an anomalous drop of the c-lattice parameter and an abrupt change of the β-monoclinic angle that could be correlated to the anomalies observed in previous specific heat measurements. Distinct changes in the quasielastic region of the neutron spectra are interpreted as being due to the onset and slowing-down of reorientational motions of the CH3-S group, are clearly distinguished above 130K in crystalline l-methionine. Large-amplitude motions observed at low frequencies are also activated above 275K, while other well-defined vibrations are damped. The ensemble of our results suggests that the crystalline structure of l-methionine is dynamically highly disordered above 275K, and such disorder can be linked to the flexibility of the molecular thiol-ether group.
Collapse
|
8
|
Szymański S. Spin-lattice relaxation of the methyl group protons in solids revisited: damped quantum rotation approach. J Chem Phys 2012; 137:034513. [PMID: 22830717 DOI: 10.1063/1.4734251] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Proton spin-lattice relaxation of the methyl group in solids had been one of the most thoroughly addressed theoretical problems in nuclear magnetic resonance (NMR) spectroscopy, considered at different levels of sophistication. For systems with substantial quantum tunneling effects, several quantum mechanical treatments were reported, although in practical applications the quantum models were always augmented with or replaced by the classical jump model. However, the latter has recently proved invalid in the description of NMR line shape effects in variable-temperature spectra of hindered methyl groups, while the competing theory of damped quantum rotation (DQR) was shown to be adequate. In this work, the spin-lattice relaxation issue for the methyl protons is readdressed using the latter theory. The main outcome is that, while the existing formulas for the relaxation rates remain unchanged, the crucial parameter entering them, the correlation time of the relevant random process, need to be reinterpreted. It proves to be the inverse of one of the two quantum-rate constants entering the DQR model, neither of which, when taken separately, can be related to the jump process. It can be identified with one describing the life-time broadening of the tunnel peaks in inelastic neutron scattering (INS) spectra of the methyl groups. Such a relationship between the relaxation and INS effects was reported from another laboratory long ago, but only for the low-temperature limit where thermal population of the excited torsional levels of the methyl group can be neglected. The whole spectrum of cases encountered in practical relaxation studies on protonated methyl groups is addressed for the first time. Preliminary experimental confirmation of this novel approach is reported, based on already published NMR data for a single crystal of methylmalonic acid. The once extensively debated issues of quenching of the coherent tunneling and of the classical limit in the dynamics of the methyl groups are readdressed and presented in a consistent manner.
Collapse
Affiliation(s)
- S Szymański
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland.
| |
Collapse
|
9
|
Latanowicz L. Proton Spin−Lattice Relaxation of Tunneling Methyl Groups: Calculation of the Time Dependent Correlation Functions. J Phys Chem A 2004. [DOI: 10.1021/jp047668a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- L. Latanowicz
- Institute of Biotechnology and Environmental Sciences, University of Zielona Góra, Monte Cassino 21 B, 65-651 Zielona Góra, Poland
| |
Collapse
|
10
|
Głowinkowski S, Peplińska B, Jurga S. Molecular dynamics in solid pyridoxine as studied by 1H NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2004; 25:1-4. [PMID: 14698377 DOI: 10.1016/j.ssnmr.2003.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Spin-lattice relaxation times T1 and T1d as well as NMR second moment were employed to study molecular dynamics of pyridoxine (vitamin B6) in the temperature range 10-350 K. The T1 minimum observed at low temperatures at 200 MHz is attributed to a motion of methyl group. The motion is interpreted in terms of Haupt's theory, which takes into account the tunneling assisted relaxation. At low temperatures, where T1 is temperature independent, occupation of the ground state only is assumed. A motion of proton of the hydroxyl groups or CH2OH groups probably provides additional mechanism of relaxation, in the high-temperature region.
Collapse
Affiliation(s)
- S Głowinkowski
- Institute of Physics, A. Mickiewicz University, Ul. Umultowska 85, 61-614 Poznań, Poland.
| | | | | |
Collapse
|
11
|
Medycki W. Classical and quantum molecular dynamics of cation in (CH3NH3)3 Sb2Br9 polycrystal as studied by 1H NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1999; 14:137-143. [PMID: 10499659 DOI: 10.1016/s0926-2040(99)00025-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
1H spin-lattice relaxation times and second moments were determined for polycrystalline (CH3NH3)3Sb2Br9 sample in a wide range of temperature (5-200 K) at 24.6 and 55.2 MHz. 2H NMR spectra of (CD3NH3)3Sb2Br9 were recorded between 5 K and room temperature. The relaxation time is interpreted as a result of motion of two different non-equivalent types of monomethylammonium cations occurring at the 2:1 proportion in a unit cell. Below 30 K, the relaxation processes via tunneling are suggested to dominate. Above 30 K, only classical behaviour of methylammonium cations is detected. Two monomethylammonium cations relax with the classical correlated C3 reorientation and the rotational tunnelling mechanism, while the third cation exhibits only the classical correlated reorientation. The dynamic parameters of these motions have been determined.
Collapse
Affiliation(s)
- W Medycki
- Institute of Molecular Physics, PAS, Poznań, Poland.
| |
Collapse
|
12
|
Limbach HH, Ulrich S, Gründemann S, Buntkowsky G, Sabo-Etienne S, Chaudret B, Kubas GJ, Eckert J. NMR and INS Line Shapes of Transition Metal Hydrides in the Presence of Coherent and Incoherent Dihydrogen Exchange. J Am Chem Soc 1998. [DOI: 10.1021/ja962903r] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hans-Heinrich Limbach
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Stefan Ulrich
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Stephan Gründemann
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Gerd Buntkowsky
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Sylviane Sabo-Etienne
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Bruno Chaudret
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Gregory J. Kubas
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| | - Jürgen Eckert
- Contribution from the Institut für Organische Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, the Laboratoire de Chimie de Coordination du CNRS (UP 8241), 205, route de Narbonne, F-31077 Toulouse-Cedex, France, and LANSCE, Los Alamos National Laboratory, Los Alamos, Mail Stop H805, New Mexico 87545
| |
Collapse
|
13
|
Kuhnen A, Vermathen P, Müller-Warmuth W. Methyl tunnelling, reorientation and NMR relaxation in solid acetates. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1998; 10:161-168. [PMID: 9550344 DOI: 10.1016/s0926-2040(97)00025-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Rotational excitations of methyl groups in six solid acetates have been investigated by 1H nuclear magnetic resonance (NMR) relaxation time measurements at 15 MHz and 30 MHz and at temperatures between 10 K and the melting point. Hindering barriers between 1.6 kJ/mol and 3.7 kJ/mol have been found that could be correlated to the tunnelling frequencies observed by inelastic neutron scattering. A consistent description of the relaxation rate dependences from the classical regime at high temperatures to the quantum-mechanical regime at low temperatures is possible by Haupt's equation. The rotational potentials are mainly determined by inter-molecular interaction with an important influence of water of crystallization, if present.
Collapse
Affiliation(s)
- A Kuhnen
- Institut für Physikalische Chemie, der Westfälischen Wilhelms-Universität, Münster, Germany
| | | | | |
Collapse
|
14
|
Prager M, Heidemann A. Rotational Tunneling and Neutron Spectroscopy: A Compilation. Chem Rev 1997; 97:2933-2966. [PMID: 11851482 DOI: 10.1021/cr9500848] [Citation(s) in RCA: 209] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Prager
- Institut Laue-Langevin, B.P. 156, F-38042 Grenoble, France
| | | |
Collapse
|
15
|
The origin and temperature dependence of the single particle, methyl-group rotational potential in acetic acid. Chem Phys 1997. [DOI: 10.1016/s0301-0104(96)00367-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|