1
|
Yokoo H, Tanaka S, Yamamoto E, Tsuji G, Demizu Y, Uchiyama N. Advanced Solid-State NMR Analysis of Two Crystal Forms of Ranitidine Hydrochloride: Detection of 1H- 14N Intra-/Intermolecular Correlations. Chem Pharm Bull (Tokyo) 2023; 71:58-63. [PMID: 36288936 DOI: 10.1248/cpb.c22-00628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Understanding the characteristics of crystal polymorphism of active pharmaceutical ingredients and analyzing them with high sensitivity is important for quality of drug products, appropriate characterization strategies, and appropriate screening and selection processes. However, there are few methods to measure intra- and intermolecular correlations in crystals other than X-ray crystallography, for which it is sometimes difficult to obtain suitable single crystals. Recently, solid-state NMR has been recognized as a straightforward method for measuring molecular correlations. In this study, we selected ranitidine hydrochloride, which is known to exist in two forms, 1 and 2, as the model drug and investigated each form using solid-state NMR. In conducting the analysis, rotating the sample tube, which had a 1-mm inner diameter, increased the solid-state NMR resolution at 70 kHz. The 1H-14N dipolar-based heteronuclear multiple quantum coherence (D-HMQC) analysis revealed the intermolecular correlation of Form 1 between the N atom of the nitro group and a proton of the furan moiety, which were closer than those of the intramolecular correlation reported using single X-ray crystal analysis. Thus, 1H-14N D-HMQC analysis could be useful for characterizing intermolecular interaction in ranitidine hydrochloride crystals. In addition, we reassigned the 13C solid-state NMR signals of ranitidine hydrochloride according to the liquid-state and multiple solid-state NMR experiments.
Collapse
Affiliation(s)
- Hidetomo Yokoo
- National Institute of Health Sciences.,Medical Chemistry, Graduate School of Medical Science, Kyoto Prefectural University of Medicine
| | | | | | | | | | | |
Collapse
|
2
|
Duong NT, Nishiyama Y. Detection of remote proton-nitrogen correlations by 1H-detected 14N overtone solid-state NMR at fast MAS. Phys Chem Chem Phys 2022; 24:10717-10726. [PMID: 35315474 DOI: 10.1039/d2cp00155a] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Detecting proton and nitrogen correlations in solid-state nuclear magnetic resonance (NMR) is important for the structural determination of biological and chemical systems. Recent advances in proton detection-based approaches under fast magic-angle spinning have facilitated the detection of 1H-14N correlations by solid-state NMR. However, observing remote 1H-14N correlations by these approaches is still a challenge, especially for 14N sites having large quadrupolar couplings. To address this issue, we introduce the 1H-14N overtone continuous wave rotational-echo saturation-pulse double-resonance (1H-14N OT CW-RESPDOR) sequence. Unlike regular 2D correlation experiments where the indirect dimension is recorded in the time domain, the 1H-14N OT CW-RESPDOR experiment is directly observed in the frequency domain. A set of 1H-14N OT CW-RESPDOR filtered 1H spectra is recorded at varying 14N OT frequencies. Thanks to the selective nature of the 14N OT pulse, the filtered 1H spectra appear only if the 14N OT frequency hits the positions of the 14N OT central band or one of the spinning sidebands. This set of filtered 1H spectra represents a 2D 1H-14N OT correlation map. We have also investigated the optimizable parameters for CW-RESPDOR and figured out that these parameters are not strictly needed for our working magnetic field of 14.1 T. Hence, the experiment is easy to set up and requires almost no optimization. We have demonstrated the experimental feasibility of 1H-14N OT CW-RESPDOR on monoclinic L-histidine and L-alanyl L-alanine. The remote 1H-14N correlations have been efficiently detected, no matter how large the 14N quadrupolar interaction is, and agree with the crystal structures. In addition, based on the remote 1H-14N correlations from the non-protonated 14N site of L-histidine, we can unambiguously distinguish the orthorhombic and monoclinic forms.
Collapse
Affiliation(s)
- Nghia Tuan Duong
- Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan.
| | - Yusuke Nishiyama
- Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa 230-0045, Japan. .,JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan
| |
Collapse
|
3
|
Koptyug IV, Stern Q, Jannin S, Elliott SJ. Frozen water NMR lineshape analysis enables absolute polarization quantification. Phys Chem Chem Phys 2022; 24:5956-5964. [PMID: 35195621 DOI: 10.1039/d1cp05127j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Typical magnetic resonance experiments are routinely limited by weak signal responses. In some cases, the low intrinsic sensitivity can be alleviated by the implementation of hyperpolarization technologies. Dissolution-dynamic nuclear polarization offers a means of hyperpolarizing small molecules. Hyperpolarized water is employed in several dynamic nuclear polarization studies, and hence accurate and rapid quantification of the 1H polarization level is of utmost importance. The solid-state nuclear magnetic resonance spectrum of water acquired under dissolution-dynamic nuclear polarization conditions has revealed lineshapes which become asymmetric at high levels of 1H polarization, which is an interesting fundamental problem in itself, but also complicates data interpretation and can prevent correct estimations of polarization levels achieved. In previous studies, attempts to simulate the 1H spectral lineshape of water as a function of the 1H polarization led to significant disagreement with the experimental results. Here we propose and demonstrate that such simulations, and therefore polarization quantification, can be implemented accurately, in particular by taking into account the detector dead time during 1H signal acquisition that can lead to severe spectral distortions. Based on these findings, we employed an echo-based radiofrequency pulse sequence to achieve distortion-free 1H spectra of hyperpolarized water, and adequate simulations of these echo-based spectra were implemented to extract the absolute 1H polarization level from the hyperpolarized water signal only, thus alleviating the need for lengthy and insensitive measurements of thermal equilibrium signals.
Collapse
Affiliation(s)
- Igor V Koptyug
- International Tomography Center, SB RAS, 3A Institutskaya St., Novosibirsk, 630090, Russia
| | - Quentin Stern
- Univ. Lyon, CNRS, ENS Lyon, UCBL, Université de Lyon, CRMN UMR 5280, 69100 Villeurbanne, France.
| | - Sami Jannin
- Univ. Lyon, CNRS, ENS Lyon, UCBL, Université de Lyon, CRMN UMR 5280, 69100 Villeurbanne, France.
| | - Stuart J Elliott
- Univ. Lyon, CNRS, ENS Lyon, UCBL, Université de Lyon, CRMN UMR 5280, 69100 Villeurbanne, France.
| |
Collapse
|
4
|
14N, 13C, and 119Sn solid-state NMR characterization of tin(II) carbodiimide Sn(NCN). ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2021. [DOI: 10.1515/znb-2021-0122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We report the first magic-angle spinning (MAS) nuclear magnetic resonance (NMR) study on Sn(NCN). In this compound the spatially elongated (NCN)2− ion is assumed to develop two distinct forms: either cyanamide (N≡C–N2−) or carbodiimide (−N=C=N−). Our 14N MAS NMR results reveal that in Sn(NCN) the (NCN)2− groups exist exclusively in the form of symmetric carbodiimide ions with two equivalent nitrogen sites, which is in agreement with the X-ray diffraction data. The 14N quadrupolar coupling constant
|
C
Q
|
$\vert {C}_{\text{Q}}\vert $
≈ 1.1 MHz for the −N=C=N− ion in Sn(NCN) is low when compared to those observed in molecular compounds that comprise cyano-type N≡C– moieties (
|
C
Q
|
$\vert {C}_{\text{Q}}\vert $
> 3.5 MHz). This together with the information from 14N and 13C chemical shifts indicates that solid-state NMR is a powerful tool for providing atomic-level insights into anion species present in these compounds. The experimental NMR results are corroborated by high-level calculations with quantum chemistry methods.
Collapse
|
5
|
Duong NT, Gan Z, Nishiyama Y. Selective 1H- 14N Distance Measurements by 14N Overtone Solid-State NMR Spectroscopy at Fast MAS. Front Mol Biosci 2021; 8:645347. [PMID: 33898521 PMCID: PMC8061749 DOI: 10.3389/fmolb.2021.645347] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 01/28/2021] [Indexed: 01/25/2023] Open
Abstract
Accurate distance measurements between proton and nitrogen can provide detailed information on the structures and dynamics of various molecules. The combination of broadband phase-modulated (PM) pulse and rotational-echo saturation-pulse double-resonance (RESPDOR) sequence at fast magic-angle spinning (MAS) has enabled the measurement of multiple 1H-14N distances with high accuracy. However, complications may arise when applying this sequence to systems with multiple inequivalent 14N nuclei, especially a single 1H sitting close to multiple 14N atoms. Due to its broadband characteristics, the PM pulse saturates all 14N atoms; hence, the single 1H simultaneously experiences the RESPDOR effect from multiple 1H-14N couplings. Consequently, no reliable H-N distances are obtained. To overcome the problem, selective 14N saturation is desired, but it is difficult because 14N is an integer quadrupolar nucleus. Alternatively, 14N overtone (OT) NMR spectroscopy can be employed owing to its narrow bandwidth for selectivity. Moreover, owing to the sole presence of two energy levels (m = ± 1), the 14N OT spin dynamics behaves similarly to that of spin-1/2. This allows the interchangeability between RESPDOR and rotational-echo double-resonance (REDOR) since their principles are the same except the degree of 14N OT population transfer; saturation for the former whereas inversion for the latter. As the ideal saturation/inversion is impractical due to the slow and orientation-dependent effective nutation of 14N OT, the working condition is usually an intermediate between REDOR and RESPDOR. The degree of 14N OT population transfer can be determined from the results of protons with short distances to 14N and then can be used to obtain long-distance determination of other protons to the same 14N site. Herein, we combine the 14N OT and REDOR/RESPDOR to explore the feasibility of selective 1H-14N distance measurements. Experimental demonstrations on simple biological compounds of L-tyrosine.HCl, N-acetyl-L-alanine, and L-alanyl-L-alanine were performed at 14.1 T and MAS frequency of 62.5 kHz. The former two consist of a single 14N site, whereas the latter consists of two 14N sites. The experimental optimizations and reliable fittings by the universal curves are described. The extracted 1H-14N distances by OT-REDOR are in good agreement with those determined by PM-RESPDOR and diffraction techniques.
Collapse
Affiliation(s)
- Nghia Tuan Duong
- NMR Science and Development Division, RIKEN SPring-8 Center, Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Japan
| | - Zhehong Gan
- Centre of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Yusuke Nishiyama
- NMR Science and Development Division, RIKEN SPring-8 Center, Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Yokohama, Japan
- JEOL RESONANCE Inc., Tokyo, Japan
| |
Collapse
|
6
|
Paluch P, Rankin AGM, Trébosc J, Lafon O, Amoureux JP. Analysis of HMQC experiments applied to a spin ½ nucleus subject to very large CSA. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 100:11-25. [PMID: 30908976 DOI: 10.1016/j.ssnmr.2019.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
The acquisition of solid-state NMR spectra of "heavy" spin I = 1/2 nuclei, such as 119Sn, 195Pt, 199Hg or 207Pb can often prove challenging due to the presence of large chemical shift anisotropy (CSA), which can cause significant broadening of spectral lines. However, previous publications have shown that well-resolved spectra can be obtained via inverse 1H detection using HMQC experiments in combination with fast magic angle spinning. In this work, the efficiencies of different 195Pt excitation schemes are analyzed using SIMPSON numerical simulations and experiments performed on cis- and transplatin samples. These schemes include: hard pulses (HP), selective long pulses (SLP) and rotor-synchronized DANTE trains of pulses. The results show that for spectra of species with very large CSA, HP is little efficient, but that both DANTE and SLP provide efficient excitation profiles over a wide range of CSA values. In particular, it is revealed that the SLP scheme is highly robust to offset, pulse amplitude and length, and is simple to set up. These factors make SLP ideally suited to widespread use by "non-experts" for carrying out analyses of materials containing "heavy" spin I = 1/2 nuclei that are subject to very large CSAs. Finally, the existence of an "intermediate" excitation regime, with an rf-field strength in between those of HP and SLP, which is effective for large CSA, is demonstrated. It must be noted that in some samples, multiple sites may exist with very different CSAs. This is the case for 195Pt species with either square-planar or octahedral structures, with large or small CSA, respectively. These two types of CSAs can only be excited simultaneously with DANTE trains, which scale up the effective rf-field. Another way to obtain all the information is to perform two different experiments: one with SLP and the second with HP to excite the sites with moderate/large and small/moderate CSAs, respectively. These two complementary experiments, recorded with two different spinning speeds, can also be used to discriminate the center-band resonances from the spinning sidebands.
Collapse
Affiliation(s)
- Piotr Paluch
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90 363 Lodz, Poland; Univ. Lille, CNRS 8181, UCCS: Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France.
| | - Andrew G M Rankin
- Univ. Lille, CNRS 8181, UCCS: Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France
| | - Julien Trébosc
- Univ. Lille, CNRS 8181, UCCS: Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France
| | - Olivier Lafon
- Univ. Lille, CNRS 8181, UCCS: Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Institut Universitaire de France, 1 Rue Descartes, F-75231 Paris Cedex 05, France
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS 8181, UCCS: Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Bruker Biospin, 34 Rue de L'Industrie, F-67166 Wissembourg, France.
| |
Collapse
|
7
|
Carnevale D, Pelupessy P, Bodenhausen G. Cross-term Splittings Due to the Orientational Inequivalence of Proton Magnetic Shielding Tensors: Do Water Molecules Trapped in Crystals Hop or Tunnel? J Phys Chem Lett 2019; 10:3224-3231. [PMID: 31059264 DOI: 10.1021/acs.jpclett.9b00914] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Water molecules trapped in crystals of barium chlorate monohydrate have been investigated by magic-angle spinning (MAS) proton NMR spectroscopy in the temperature range 110-300 K. At high temperatures, a single spinning sideband pattern is observed. Below 150 K, however, two interleaved spinning sideband manifolds appear, with distinct centerbands that do not coincide with the average isotropic chemical shift seen at high temperatures. This hitherto unknown "cross-term splitting" results from the interplay of the homonuclear dipole-dipole coupling and two anisotropic proton shielding tensors that have identical principal components but nonequivalent orientations. The resulting cross terms cannot be averaged out by rotation about the magic angle. The analysis of the exchange-induced broadening, coalescence, and narrowing of the cross-term splitting in MAS spectra allows one to estimate the rate of exchange of the two protons between 140 and 190 K. The experimental data is compared with 2H and 1H NMR studies of the same sample reported in the literature. Density functional theory methods are utilized to estimate the thermal activation energy for a 2-fold hopping process of proton exchange about the H-O-H bisector. The Bell-Limbach model allows one to take into account contributions due to incoherent quantum tunneling in the low-temperature regime.
Collapse
Affiliation(s)
- Diego Carnevale
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
| | - Philippe Pelupessy
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
| | - Geoffrey Bodenhausen
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
| |
Collapse
|
8
|
Rankin AGM, Trébosc J, Paluch P, Lafon O, Amoureux JP. Evaluation of excitation schemes for indirect detection of 14N via solid-state HMQC NMR experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 303:28-41. [PMID: 30999136 DOI: 10.1016/j.jmr.2019.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 06/09/2023]
Abstract
It has previously been shown that 14N NMR spectra can be reliably obtained through indirect detection via HMQC experiments. This method exploits the transfer of coherence between single-(SQ) or double-quantum (DQ) 14N coherences, and SQ coherences of a suitable spin-1/2 'spy' nucleus, e.g., 1H. It must be noted that SQ-SQ methods require a carefully optimized setup to minimize the broadening related to the first-order quadrupole interaction (i.e., an extremely well-adjusted magic angle and a highly stable spinning speed), whereas DQ-SQ ones do not. In this work, the efficiencies of four 14N excitation schemes (DANTE, XiX, Hard Pulse (HP), and Selective Long Pulse (SLP)) are compared using J-HMQC based numerical simulations and either SQ-SQ or DQ-SQ 1H-{14N} D-HMQC experiments on l-histidine HCl and N-acetyl-l-valine at 18.8 T and 62.5 kHz MAS. The results demonstrate that both DANTE and SLP provide a more efficient 14N excitation profile than XiX and HP. Furthermore, it is shown that the SLP scheme: (i) is efficient over a large range of quadrupole interaction, (ii) is highly robust to offset and rf-pulse length and amplitude, and (iii) is very simple to set up. These factors make SLP ideally suited to widespread, non-specialist use in solid-state NMR analyses of nitrogen-containing materials.
Collapse
Affiliation(s)
- Andrew G M Rankin
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France.
| | - Julien Trébosc
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Univ. Lille, CNRS-FR2638, Fédération Chevreul, F-59000 Lille, France
| | - Piotr Paluch
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, PL-90363 Lodz, Poland
| | - Olivier Lafon
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Institut Universitaire de France, 1 rue Descartes, F-75231 Paris Cedex 05, France
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unit of Catalysis and Chemistry of Solids, F-59000 Lille, France; Bruker Biospin, 34 rue de l'industrie, F-67166 Wissembourg, France.
| |
Collapse
|
9
|
Perras FA, Goh TW, Wang LL, Huang W, Pruski M. Enhanced 1H-X D-HMQC performance through improved 1H homonuclear decoupling. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 98:12-18. [PMID: 30669006 DOI: 10.1016/j.ssnmr.2019.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/05/2019] [Accepted: 01/06/2019] [Indexed: 06/09/2023]
Abstract
The sensitivity of solid-state NMR experiments that utilize 1H zero-quantum heteronuclear dipolar recoupling, such as D-HMQC, is compromised by poor homonuclear decoupling. This leads to a rapid decay of recoupled magnetization and an inefficient recoupling of long-range dipolar interactions, especially for nuclides with low gyromagnetic ratios. We investigated the use, in symmetry-based 1H heteronuclear recoupling sequences, of a basic R element that was principally designed for efficient homonuclear decoupling. By shortening the time required to suppress the effects of homonuclear dipolar interactions to the duration of a single inversion pulse, spin diffusion was effectively quenched and long-lived recoupled coherence lifetimes could be obtained. We show, both theoretically and experimentally, that these modified sequences can yield considerable sensitivity improvements over the current state-of-the-art methods and applied them to the indirect detection of 89Y in a metal-organic framework.
Collapse
Affiliation(s)
| | - Tian Wei Goh
- US Department of Energy, Ames Laboratory, Ames, IA, 50011, USA; Department of Chemistry, Iowa State University, Ames, IA, 50011, USA
| | - Lin-Lin Wang
- US Department of Energy, Ames Laboratory, Ames, IA, 50011, USA
| | - Wenyu Huang
- US Department of Energy, Ames Laboratory, Ames, IA, 50011, USA; Department of Chemistry, Iowa State University, Ames, IA, 50011, USA
| | - Marek Pruski
- US Department of Energy, Ames Laboratory, Ames, IA, 50011, USA; Department of Chemistry, Iowa State University, Ames, IA, 50011, USA.
| |
Collapse
|
10
|
Li Y, Trébosc J, Hu B, Shen M, Amoureux JP, Lafon O. Indirect detection of broad spectra in solid-state NMR using interleaved DANTE trains. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 294:101-114. [PMID: 30032034 DOI: 10.1016/j.jmr.2018.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 07/03/2018] [Accepted: 07/07/2018] [Indexed: 06/08/2023]
Abstract
We analyze the performances and the optimization of 1H-{I} HMQC experiments using basic and interleaved DANTE schemes for the indirect detection of nuclei I = 1/2 or 1 exhibiting wide lines dominated by chemical shift anisotropy (CSA) or quadrupole interaction, respectively. These sequences are first described using average Hamiltonian theory. Then, we analyze using numerical simulations (i) the optimal lengths of the DANTE train and the individual pulses, (ii) the robustness of these experiments to offset, and (iii) the optimal choice of the defocusing and refocusing times for both 1H-{I} J- and D-HMQC sequences for 195Pt (I = 1/2) and 14N (I = 1) nuclei subject to large CSA and quadrupole interaction, respectively. These simulations are compared to 1H-{14N} D-HMQC experiments on γ-glycine and L-histidine.HCl at B0 = 18.8 T and MAS frequency of 62.5 kHz. The present study shows that (i) the optimal defocusing and refocusing times do not depend on the chosen DANTE scheme, (ii) the DANTE trains must be applied with the highest rf-field compatible with the probe specifications and the stability of the sample, (iii) the excitation bandwidth along the indirect dimension of HMQC sequence using DANTE trains is inversely proportional to their length, (iv) interleaved DANTE trains increase the excitation bandwidth of these sequences, and (v) dephasing under residual 1H-1H and 1H-I dipolar couplings, as well as 14N second-order quadrupole interaction, during the length of the DANTE scheme attenuate the transfer efficiency.
Collapse
Affiliation(s)
- Yixuan Li
- Univ. Lille, CNRS, UMR 8181-UCCS, Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France; Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
| | - Julien Trébosc
- Univ. Lille, CNRS, UMR 8181-UCCS, Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France
| | - Bingwen Hu
- Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
| | - Ming Shen
- Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS, UMR 8181-UCCS, Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France; Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China; Bruker France, 34 rue de l'Industrie, F-67166 Wissembourg, France.
| | - Olivier Lafon
- Univ. Lille, CNRS, UMR 8181-UCCS, Unité de Catalyse et de Chimie du Solide, F-59000 Lille, France; Institut Universitaire de France, 1, rue Descartes, 75231 Paris, France.
| |
Collapse
|
11
|
Nimerovsky E, Makrinich M, Goldbourt A. Analysis of large-anisotropy-spin recoupling pulses for distance measurement under magic-angle spinning NMR shows the superiority and robustness of a phase modulated saturation pulse. J Chem Phys 2018; 146:124202. [PMID: 28388136 DOI: 10.1063/1.4978472] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The distance between a spin one-half and an attached spin possessing a large anisotropy can be obtained using different dipolar recoupling sequences that are based on the rotational-echo double resonance technique under magic-angle spinning solid-state NMR. The general difference between these sequences with respect to the coupled spin is the set of pulses applied in order to drive this spin out of equilibrium, thereby recoupling the dipolar interaction. Since complete inversion is practically not possible due to the coupled-spin anisotropy, using one or another pulse depends on the experimental and spin conditions: the spinning speed, the strength of the radio frequency field, the size of the anisotropic interaction (quadrupolar or chemical shiftanisotropy couplings), the offset, and the accuracy of setting the magic angle. Here we present a detailed description of the behavior of the anisotropic spin magnetization, including the macroscopic level transition probabilities, the degree of inversion, and the microscopic and macroscopic magnetizations during the applications of these pulses under different experimental conditions. As simulations show, a complete randomization of spin populations under a wide range of experimental conditions occurs under a specific phase modulation of the recoupling pulse while for all other cases dependence on experimental conditions is large and the achievable bandwidth is limited. A result of this detailed analysis is that the extension of the phase modulated pulse extends even further its robustness. The saturation capability is demonstrated experimentally for the quadrupolar spin of boron-11 in 4-methoxyphenylboronic acid.
Collapse
Affiliation(s)
- E Nimerovsky
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | - M Makrinich
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | - A Goldbourt
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
12
|
Nagashima H, Tricot G, Trébosc J, Lafon O, Amoureux JP, Pourpoint F. 3D correlation NMR spectrum between three distinct heteronuclei for the characterization of inorganic samples: Application on sodium alumino-phosphate materials. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2017; 84:164-170. [PMID: 28351540 DOI: 10.1016/j.ssnmr.2017.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/03/2017] [Accepted: 03/13/2017] [Indexed: 06/06/2023]
Abstract
We report here an original NMR sequence allowing the acquisition of 3D correlation NMR spectra between three distinct heteronuclei, among which two are half-integer spin quadrupolar nuclei. Furthermore, as two of them exhibit close Larmor frequency, this experiment was acquired using a standard triple-resonance probe equipped with a commercial frequency splitter. This NMR technique was tested and applied to sodium alumino-phosphate compounds with 31P as the spin-1/2 nucleus and 23Na and 27Al as the close Larmor frequencies isotopes. To the best of our knowledge, such experiment with direct 31P and indirect 27Al and 23Na detection is the first example of 3D NMR experiment in solids involving three distinct heteronuclei. This sequence has first been demonstrated on a mixture of Al(PO3)3 and NaAlP2O7 crystalline phases, for which a selective observation of NaAlP2O7 is possible through the 3D map edition. This 3D correlation experiment is then applied to characterize mixing and phase segregation in a partially devitrified glass that has been proposed as a material for the sequestration of radioactive waste. The 31P-{23Na,27Al} 3D experiment conducted on the partially devitrified glass material conclusively demonstrates that the amorphous component of the material does not contain aluminum. The as-synthesized material thus presents a poor resistance against water, which is a severe limitation for its application in the radioactive waste encapsulation domain.
Collapse
Affiliation(s)
- Hiroki Nagashima
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France
| | - Grégory Tricot
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Julien Trébosc
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France
| | - Olivier Lafon
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France; Institut Universitaire de France, 1 rue Descartes, Paris Cedex 5 75231, France
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France
| | - Frédérique Pourpoint
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille, France.
| |
Collapse
|
13
|
Carnevale D, Chinthalapalli S, Bodenhausen G. Exciting Wide NMR Spectra of Static Solid Samples with Weak Radiofrequency Fields. Z PHYS CHEM 2016. [DOI: 10.1515/zpch-2016-0808] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Trains of short pulses in the manner of ‘delays alternating with nutations for tailored excitation’ (DANTE) have been applied to the Pake patterns of protons of water molecules trapped in a static powdered sample of barium chlorate monohydrate. The spin dynamics in the course of such experiments have been investigated by means of numerical simulations and compared with the ideal refocusing that can be achieved under magic-angle spinning (MAS). Solid echoes yield essentially undistorted lineshapes, in contrast to direct excitation without refocusing that leads to severe dispersions of the phases because of inhomogeneous interactions such as homonuclear dipolar couplings and anisotropic chemical shifts. The selectivity of DANTE sequences allows one to access ‘slices’ of the Pake pattern that can be related to particular crystallite orientations. Single-crystal spectra can therefore be extracted from powder spectra. A similar behavior is expected for both dipolar and quadrupolar echoes.
Collapse
Affiliation(s)
- Diego Carnevale
- Neuchâtel Platform of Analytical Chemistry (NPAC), Institut de Chimie, Université de Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland
- Institut des sciences et ingénierie chimiques (ISIC), Ecole Polytechnique Fédérale de La USA nne (EPFL), 1015 La USA nne, Switzerland
| | - Srinivas Chinthalapalli
- Institut des sciences et ingénierie chimiques (ISIC), Ecole Polytechnique Fédérale de La USA nne (EPFL), 1015 La USA nne, Switzerland
- Analytical and Spectroscopy Division (ASD), Analytical, Spectroscopy and Ceramics Group (ASCG), Propellants, Polymers, Chemicals and Materials (PCM) Entity, Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram 695 022, India
| | - Geoffrey Bodenhausen
- Institut des sciences et ingénierie chimiques (ISIC), Ecole Polytechnique Fédérale de La USA nne (EPFL), 1015 La USA nne, Switzerland
- Departement de Chimie, Ecole Normale Superieure, PSL Research University, UPMC Univ Paris 06, CNRS, Laboratoire des Biomolecules (LBM), 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universites, UPMC Univ Paris 06, Ecole Normale Superieure, CNRS, Laboratoire des Biomolecules (LBM), Paris, France
| |
Collapse
|
14
|
Shen M, Trébosc J, Lafon O, Gan Z, Pourpoint F, Hu B, Chen Q, Amoureux JP. Solid-state NMR indirect detection of nuclei experiencing large anisotropic interactions using spinning sideband-selective pulses. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:104-117. [PMID: 26411981 DOI: 10.1016/j.ssnmr.2015.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/04/2015] [Accepted: 09/04/2015] [Indexed: 06/05/2023]
Abstract
Under Magic-Angle Spinning (MAS), a long radio-frequency (rf) pulse applied on resonance achieves the selective excitation of the center-band of a wide NMR spectrum. We show herein that these rf pulses can be applied on the indirect channel of Hetero-nuclear Multiple-Quantum Correlation (HMQC) sequences, which facilitate the indirect detection via spin-1/2 isotopes of nuclei exhibiting wide spectra. Numerical simulations show that this indirect excitation method is applicable to spin-1/2 nuclei experiencing a large chemical shift anisotropy, as well as to spin-1 isotopes subject to a large quadrupole interaction, such as (14)N. The performances of the long pulses are analyzed by the numerical simulations of scalar-mediated HMQC (J-HMQC) experiments indirectly detecting spin-1/2 or spin-1 nuclei, as well as by dipolar-mediated HMQC (D-HMQC) experiments achieving indirect detection of (14)N nuclei via (1)H in crystalline γ-glycine and N-acetyl-valine samples at a MAS frequency of 60kHz. We show on these solids that for the acquisition of D-HMQC spectra between (1)H and (14)N nuclei, the efficiency of selective moderate excitation with long-pulses at the (14)N Larmor frequency, ν0((14)N), is comparable to those with strong excitation pulses at ν0((14)N) or 2ν0((14)N) frequencies, given the rf field delivered by common solid-state NMR probes. Furthermore, the D-HMQC experiments also demonstrate that the use of long pulses does not produce significant spectral distortions along the (14)N dimension. In summary, the use of center-band selective weak pulses is advantageous for HMQC experiments achieving the indirect detection of wide spectra since it (i) requires a moderate rf field, (ii) can be easily optimized, (iii) displays a high robustness to CSAs, offsets, rf-field inhomogeneities, and fluctuations in MAS frequency, and (iv) is little dependent on the quadrupolar coupling constant.
Collapse
Affiliation(s)
- Ming Shen
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Julien Trébosc
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France
| | - Olivier Lafon
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France.
| | - Zhehong Gan
- Center of Interdisciplinary Magnetic Resonance, NHMFL, Tallahassee, FL 32310, USA
| | | | - Bingwen Hu
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Qun Chen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Jean-Paul Amoureux
- UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
| |
Collapse
|
15
|
Shen M, Trébosc J, O'Dell LA, Lafon O, Pourpoint F, Hu B, Chen Q, Amoureux JP. Comparison of various NMR methods for the indirect detection of nitrogen-14 nuclei via protons in solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 258:86-95. [PMID: 26232366 DOI: 10.1016/j.jmr.2015.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 06/11/2015] [Accepted: 06/18/2015] [Indexed: 06/04/2023]
Abstract
We present an experimental comparison of several through-space Hetero-nuclear Multiple-Quantum Correlation experiments, which allow the indirect observation of homo-nuclear single- (SQ) or double-quantum (DQ) (14)N coherences via spy (1)H nuclei. These (1)H-{(14)N} D-HMQC sequences differ not only by the order of (14)N coherences evolving during the indirect evolution, t1, but also by the radio-frequency (rf) scheme used to excite and reconvert these coherences under Magic-Angle Spinning (MAS). Here, the SQ coherences are created by the application of center-band frequency-selective pulses, i.e. long and low-power rectangular pulses at the (14)N Larmor frequency, ν0((14)N), whereas the DQ coherences are excited and reconverted using rf irradiation either at ν0((14)N) or at the (14)N overtone frequency, 2ν0((14)N). The overtone excitation is achieved either by constant frequency rectangular pulses or by frequency-swept pulses, specifically Wide-band, Uniform-Rate, and Smooth-Truncation (WURST) pulse shapes. The present article compares the performances of four different (1)H-{(14)N} D-HMQC sequences, including those with (14)N rectangular pulses at ν0((14)N) for the indirect detection of homo-nuclear (i) (14)N SQ or (ii) DQ coherences, as well as their overtone variants using (iii) rectangular or (iv) WURST pulses. The compared properties include: (i) the sensitivity, (ii) the spectral resolution in the (14)N dimension, (iii) the rf requirements (power and pulse length), as well as the robustness to (iv) rf offset and (v) MAS frequency instabilities. Such experimental comparisons are carried out for γ-glycine and l-histidine.HCl monohydrate, which contain (14)N sites subject to moderate quadrupole interactions. We demonstrate that the optimum choice of the (1)H-{(14)N} D-HMQC method depends on the experimental goal. When the sensitivity and/or the robustness to offset are the major concerns, the D-HMQC sequence allowing the indirect detection of (14)N SQ coherences should be employed. Conversely, when the highest resolution and/or adjusted indirect spectral width are needed, overtone experiments are the method of choice. The overtone scheme using WURST pulses results in broader excitation bandwidths than that using rectangular pulses, at the expense of reduced sensitivity. Numerically exact simulations also show that the sensitivity of the overtone (1)H-{(14)N} D-HMQC experiment increases for larger quadrupole interactions.
Collapse
Affiliation(s)
- Ming Shen
- UCCS, CNRS UMR 8181, Univ. Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Julien Trébosc
- UCCS, CNRS UMR 8181, Univ. Lille, Villeneuve d'Ascq 59652, France
| | - Luke A O'Dell
- Institute for Frontier Materials, Deakin University, Waurn Ponds Campus, Geelong, Victoria 3220, Australia
| | - Olivier Lafon
- UCCS, CNRS UMR 8181, Univ. Lille, Villeneuve d'Ascq 59652, France.
| | | | - Bingwen Hu
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Qun Chen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Jean-Paul Amoureux
- UCCS, CNRS UMR 8181, Univ. Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
| |
Collapse
|
16
|
Pell AJ, Pintacuda G. Broadband solid-state MAS NMR of paramagnetic systems. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 84-85:33-72. [PMID: 25669740 DOI: 10.1016/j.pnmrs.2014.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
The combination of new magnet and probe technology with increasingly sophisticated pulse sequences has resulted in an increase in the number of applications of solid-state nuclear magnetic resonance (NMR) spectroscopy to paramagnetic materials and biomolecules. The interaction between the paramagnetic metal ions and the NMR-active nuclei often yields crucial structural or electronic information about the system. In particular the application of magic-angle spinning (MAS) has been shown to be crucial to obtaining resolution that is sufficiently high for studying complex systems. However such systems are generally extremely difficult to study as the shifts and shift anisotropies resulting from the same paramagnetic interaction broaden the spectrum beyond excitation and detection, and the paramagnetic relaxation enhancement (PRE) shortens the lifetimes of the excited signals considerably. One specific area that has therefore been receiving significant attention in recent years, and for which great improvements have been seen, is the development of broadband NMR sequences. The development of new excitation and inversion sequences for paramagnetic systems under MAS has often made the difference between the spectrum being unobtainable, and a complete NMR study being possible. However the development of the new sequences must explicitly take account of the modulation of the anisotropic shift interactions due to the sample rotation, with the resulting spin dynamics often being complicated considerably. The NMR sequences can either be helped or hindered by MAS, with the efficiency of some pulse schemes being destroyed, and others being greatly enhanced. This review describes the pulse sequences that have recently been proposed for broadband excitation, inversion, and refocussing of the signal components of paramagnetic systems. In doing so we define exactly what is meant by "broadband" under spinning conditions, and what the perfect pulse scheme should deliver. We also give a unified description of the spin dynamics under MAS which highlights the strengths and weaknesses of the various schemes, and which can be used as guidance for future research in this area. All the reviewed pulse schemes are evaluated both with simulations and experimental data obtained on the battery material LiFe(0.5)Mn(0.5)PO(4) which is typical of the complexity of the paramagnetic systems that are currently under study.
Collapse
Affiliation(s)
- Andrew J Pell
- Centre de RMN à Très Hauts Champs, Université de Lyon, Institute of Analytical Sciences UMR 5280 (CNRS/CNRS, Ecole Normale Supérieure de Lyon/Lyon, Université Claude Bernard Lyon 1), 5 rue de la Doua, 69100 Villeurbanne, France.
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Université de Lyon, Institute of Analytical Sciences UMR 5280 (CNRS/CNRS, Ecole Normale Supérieure de Lyon/Lyon, Université Claude Bernard Lyon 1), 5 rue de la Doua, 69100 Villeurbanne, France.
| |
Collapse
|
17
|
Shen M, Trébosc J, Lafon O, Pourpoint F, Hu B, Chen Q, Amoureux JP. Improving the resolution in proton-detected through-space heteronuclear multiple quantum correlation NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 245:38-49. [PMID: 24929867 DOI: 10.1016/j.jmr.2014.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 06/03/2023]
Abstract
Connectivities and proximities between protons and low-gamma nuclei can be probed in solid-state NMR spectroscopy using two-dimensional (2D) proton-detected heteronuclear correlation, through Heteronuclear Multiple Quantum Correlation (HMQC) pulse sequence. The indirect detection via protons dramatically enhances the sensitivity. However, the spectra are often broadened along the indirect F1 dimension by the decay of heteronuclear multiple-quantum coherences under the strong (1)H-(1)H dipolar couplings. This work presents a systematic comparison of the performances of various decoupling schemes during the indirect t1 evolution period of dipolar-mediated HMQC (D-HMQC) experiment. We demonstrate that (1)H-(1)H dipolar decoupling sequences during t1, such as symmetry-based schemes, phase-modulated Lee-Goldburg (PMLG) and Decoupling Using Mind-Boggling Optimization (DUMBO), provide better resolution than continuous wave (1)H irradiation. We also report that high resolution requires the preservation of (1)H isotropic chemical shifts during the decoupling sequences. When observing indirectly broad spectra presenting numerous spinning sidebands, the D-HMQC sequence must be fully rotor-synchronized owing to the rotor-synchronized indirect sampling and dipolar recoupling sequence employed. In this case, we propose a solution to reduce artefact sidebands caused by the modulation of window delays before and after the decoupling application during the t1 period. Moreover, we show that (1)H-(1)H dipolar decoupling sequence using Smooth Amplitude Modulation (SAM) minimizes the t1-noise. The performances of the various decoupling schemes are assessed via numerical simulations and compared to 2D (1)H-{(13)C} D-HMQC experiments on [U-(13)C]-L-histidine⋅HCl⋅H2O at various magnetic fields and Magic Angle spinning (MAS) frequencies. Great resolution and sensitivity enhancements resulting from decoupling during t1 period enable the detection of heteronuclear correlation between aliphatic protons and ammonium (14)N sites in L-histidine⋅HCl⋅H2O.
Collapse
Affiliation(s)
- Ming Shen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - J Trébosc
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - O Lafon
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - F Pourpoint
- UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France
| | - Bingwen Hu
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - Qun Chen
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
| | - J-P Amoureux
- Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; UCCS, University Lille North of France, Villeneuve d'Ascq 59652, France.
| |
Collapse
|