1
|
Nimerovsky E, Najbauer EÉ, Becker S, Andreas LB. Great Offset Difference Internuclear Selective Transfer. J Phys Chem Lett 2023; 14:3939-3945. [PMID: 37078685 PMCID: PMC10150390 DOI: 10.1021/acs.jpclett.3c00194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Carbon-carbon dipolar recoupling sequences are frequently used building blocks in routine magic-angle spinning NMR experiments. While broadband homonuclear first-order dipolar recoupling sequences mainly excite intra-residue correlations, selective methods can detect inter-residue transfers and long-range correlations. Here, we present the great offset difference internuclear selective transfer (GODIST) pulse sequence optimized for selective carbonyl or aliphatic recoupling at fast magic-angle spinning, here, 55 kHz. We observe a 3- to 5-fold increase in intensities compared with broadband RFDR recoupling for perdeuterated microcrystalline SH3 and for the membrane protein influenza A M2 in lipid bilayers. In 3D (H)COCO(N)H and (H)CO(CO)NH spectra, inter-residue carbonyl-carbonyl correlations up to about 5 Å are observed in uniformly 13C-labeled proteins.
Collapse
Affiliation(s)
- Evgeny Nimerovsky
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Eszter Éva Najbauer
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Stefan Becker
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| | - Loren B Andreas
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, Göttingen 37077, Germany
| |
Collapse
|
2
|
Nishiyama Y, Hou G, Agarwal V, Su Y, Ramamoorthy A. Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy: Advances in Methodology and Applications. Chem Rev 2023; 123:918-988. [PMID: 36542732 PMCID: PMC10319395 DOI: 10.1021/acs.chemrev.2c00197] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Solid-state NMR spectroscopy is one of the most commonly used techniques to study the atomic-resolution structure and dynamics of various chemical, biological, material, and pharmaceutical systems spanning multiple forms, including crystalline, liquid crystalline, fibrous, and amorphous states. Despite the unique advantages of solid-state NMR spectroscopy, its poor spectral resolution and sensitivity have severely limited the scope of this technique. Fortunately, the recent developments in probe technology that mechanically rotate the sample fast (100 kHz and above) to obtain "solution-like" NMR spectra of solids with higher resolution and sensitivity have opened numerous avenues for the development of novel NMR techniques and their applications to study a plethora of solids including globular and membrane-associated proteins, self-assembled protein aggregates such as amyloid fibers, RNA, viral assemblies, polymorphic pharmaceuticals, metal-organic framework, bone materials, and inorganic materials. While the ultrafast-MAS continues to be developed, the minute sample quantity and radio frequency requirements, shorter recycle delays enabling fast data acquisition, the feasibility of employing proton detection, enhancement in proton spectral resolution and polarization transfer efficiency, and high sensitivity per unit sample are some of the remarkable benefits of the ultrafast-MAS technology as demonstrated by the reported studies in the literature. Although the very low sample volume and very high RF power could be limitations for some of the systems, the advantages have spurred solid-state NMR investigation into increasingly complex biological and material systems. As ultrafast-MAS NMR techniques are increasingly used in multidisciplinary research areas, further development of instrumentation, probes, and advanced methods are pursued in parallel to overcome the limitations and challenges for widespread applications. This review article is focused on providing timely comprehensive coverage of the major developments on instrumentation, theory, techniques, applications, limitations, and future scope of ultrafast-MAS technology.
Collapse
Affiliation(s)
- Yusuke Nishiyama
- JEOL Ltd., Akishima, Tokyo196-8558, Japan
- RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa230-0045, Japan
| | - Guangjin Hou
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian116023, China
| | - Vipin Agarwal
- Tata Institute of Fundamental Research, Sy. No. 36/P, Gopanpally, Hyderabad500 046, India
| | - Yongchao Su
- Analytical Research and Development, Merck & Co., Inc., Rahway, New Jersey07065, United States
| | - Ayyalusamy Ramamoorthy
- Biophysics, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, Michigan Neuroscience Institute, University of Michigan, Ann Arbor, Michigan41809-1055, United States
| |
Collapse
|
3
|
Xiao H, Zhang Z, Yang J. Theory of frequency-selective homonuclear dipolar recoupling in solid-state NMR. J Chem Phys 2021; 155:174105. [PMID: 34742189 DOI: 10.1063/5.0065396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In solid-state nuclear magnetic resonance, frequency-selective homonuclear dipolar recoupling is key to quantitative distance measurement or selective enhancement of correlations between atoms of interest in multiple-spin systems, which are not amenable to band-selective or broadband recoupling. Previous frequency-selective recoupling is mostly based on the so-called rotational resonance (R2) condition that restricts the application to spin pairs with resonance frequencies differing in integral multiples of the magic-angle spinning (MAS) frequency. Recently, we have proposed a series of frequency-selective homonuclear recoupling sequences called SPR (short for Selective Phase-optimized Recoupling), which have been successfully applied for selective 1H-1H or 13C-13C recoupling under from moderate (∼10 kHz) to ultra-fast (150 kHz) MAS frequencies. In this study, we fully analyze the average Hamiltonian theory of SPR sequences and reveal the origin of frequency selectivity in recoupling. The theoretical description, as well as numerical simulations and experiments, demonstrates that the frequency selectivity can be easily controlled by the flip angle (p) in the (p)ϕk(p)ϕk+π unit in the pSPR-Nn sequences. Small flip angles lead to frequency-selective recoupling, while large flip angles may lead to broadband recoupling in principle. The result shall shed new light on the design of homonuclear recoupling sequences with arbitrary frequency bandwidths.
Collapse
Affiliation(s)
- Hang Xiao
- National Center 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
| | - Zhengfeng Zhang
- National Center 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
| | - Jun Yang
- National Center 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
| |
Collapse
|
4
|
Nishiyama Y, Agarwal V, Zhang R. Efficient symmetry-based γ-encoded DQ recoupling sequences for suppression of t 1-noise in solid-state NMR spectroscopy at fast MAS. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2021; 114:101734. [PMID: 34052760 DOI: 10.1016/j.ssnmr.2021.101734] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/02/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Solid-state NMR spectroscopy has played a significant role in elucidating the structure and dynamics of materials and biological solids at a molecular level for decades. In particular, the 1H double-quantum/single-quantum (DQ/SQ) chemical shift correlation experiment is widely used for probing the proximity of protons, rendering it a powerful tool for elucidating the hydrogen-bonding interactions and molecular packing of various complex molecular systems. Two factors, namely, the DQ filtering efficiency and t1-noise, dictate the quality of the 2D 1H DQ/SQ spectra. Experimentally different recoupling sequences show varied DQ filtering efficiencies and t1-noise. Herein, after a systematic search of symmetry-based DQ recoupling sequences, we report that the symmetry-based γ-encoded RNnν sequences show superior performance to other DQ recoupling sequences, which not only have a higher DQ recoupling efficiency but can also significantly reduce t1-noise. The origin of t1-noise is further discussed in detail via extensive numerical simulations. We envisage that such γ-encoded RNnν sequences are superior candidates for DQ recoupling in proton-based solid-state NMR spectroscopy due to its capability of efficiently exciting DQ coherences and suppressing t1-noise.
Collapse
Affiliation(s)
- Yusuke Nishiyama
- RIKEN-JEOL Collaboration Center and SPring-8 Center, RIKEN, Yokohama, Kanagawa, 230-0045, Japan; JEOL RESONANCE Inc., Akishima, Tokyo, 196-8558, Japan.
| | - Vipin Agarwal
- TIFR Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, Sy. No. 36/P, Gopanpally, Ranga Reddy District, Hyderabad, 500 107, India.
| | - Rongchun Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Molecular Science and Engineering (MoSE), South China University of Technology, Guangzhou, 510640, PR China; Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, Guangzhou, 510640, PR China.
| |
Collapse
|
5
|
Ji Y, Liang L, Bao X, Hou G. Recent progress in dipolar recoupling techniques under fast MAS in solid-state NMR spectroscopy. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2021; 112:101711. [PMID: 33508579 DOI: 10.1016/j.ssnmr.2020.101711] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 12/04/2020] [Accepted: 12/05/2020] [Indexed: 06/12/2023]
Abstract
With the recent advances in NMR hardware and probe design technology, magic-angle spinning (MAS) rates over 100 kHz are accessible now, even on commercial solid NMR probes. Under such fast MAS conditions, excellent spectral resolution has been achieved by efficient suppression of anisotropic interactions, which also opens an avenue to the proton-detected NMR experiments in solids. Numerous methods have been developed to take full advantage of fast MAS during the last decades. Among them, dipolar recoupling techniques under fast MAS play vital roles in the determination of the molecular structure and dynamics, and are also key elements in multi-dimensional correlation NMR experiments. Herein, we review the dipolar recoupling techniques, especially those developed in the past two decades for fast-to-ultrafast MAS conditions. A major focus for our discussion is the ratio of RF field strength (in frequency) to MAS frequency, ν1/νr, in different pulse sequences, which determines whether these dipolar recoupling techniques are suitable for NMR experiments under fast MAS conditions. Systematic comparisons are made among both heteronuclear and homonuclear dipolar recoupling schemes. In addition, the schemes developed specially for proton-detection NMR experiments under ultrafast MAS conditions are highlighted as well.
Collapse
Affiliation(s)
- Yi Ji
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lixin Liang
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinhe Bao
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China
| | - Guangjin Hou
- State Key Laboratory of Catalysis, National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, China.
| |
Collapse
|
6
|
Yu Y, Keil P, Stevensson B, Hansen MR, Edén M. Assessment of new symmetry-based dipolar recoupling schemes for homonuclear magnetization exchange between quadrupolar nuclei in two-dimensional correlation MAS NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 316:106734. [PMID: 32590307 DOI: 10.1016/j.jmr.2020.106734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/13/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
We provide an extensive experimental and numerical evaluation of MQ-phase (S)M supercycles with M={3,4} of three groups of symmetry-based homonuclear dipolar recoupling rf-pulse sequences, [Formula: see text] , for establishing proximities among half-integer spin quadrupolar nuclei under moderately fast magic-angle-spinning (MAS) conditions in single-quantum-single-quantum (1Q-1Q) correlation NMR experiments. The relative merits of the (S)M schemes for variations in resonance offsets and rf-amplitude errors were assessed by numerically simulated magnetization transfers in spin-3/2 pairs with variable isotropic chemical shifts and quadrupolar coupling constants. Experimental demonstrations of 23Na (spin-3/2) NMR on Na2MoO4·2H2O and 27Al (spin-5/2) NMR on AlPO-CJ19 [(NH4)2Al4(PO4)4HPO4·H2O] are presented at 14.1 T and 24 kHz MAS. We recommend using the (SR221)3 or (SR221)4 supercycles for samples that exhibit small chemical-shift dispersions (<3 kHz), and any (SRNNN/2)3 scheme with N⩾10 for larger spreads of isotropic chemical shifts. However, because the (SRNNN/2)3 sequences recouple heteronuclear dipolar interactions, their application to proton-bearing samples requires high-power proton decoupling during the mixing period. Alternatively, the (SR241)3 and (SR241)4 schemes may be employed in the absence of proton decoupling, but with poorer compensation to resonance-offsets and rf-amplitude errors.
Collapse
Affiliation(s)
- Yang Yu
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Philipp Keil
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität Münster, DE-48 149 Münster, Germany
| | - Baltzar Stevensson
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Michael Ryan Hansen
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität Münster, DE-48 149 Münster, Germany
| | - Mattias Edén
- Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
| |
Collapse
|
7
|
Zhang Z, Liu H, Deng J, Tycko R, Yang J. Optimization of band-selective homonuclear dipolar recoupling in solid-state NMR by a numerical phase search. J Chem Phys 2019; 150:154201. [PMID: 31005077 DOI: 10.1063/1.5092986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spin polarization transfers among aliphatic 13C nuclei, especially 13Cα-13Cβ transfers, permit correlations of their nuclear magnetic resonance (NMR) frequencies that are essential for signal assignments in multidimensional solid-state NMR of proteins. We derive and demonstrate a new radio-frequency (RF) excitation sequence for homonuclear dipolar recoupling that enhances spin polarization transfers among aliphatic 13C nuclei at moderate magic-angle spinning (MAS) frequencies. The phase-optimized recoupling sequence with five π pulses per MAS rotation period (denoted as PR5) is derived initially from systematic numerical simulations in which only the RF phases are varied. Subsequent theoretical analysis by average Hamiltonian theory explains the favorable properties of numerically optimized phase schemes. The high efficiency of spin polarization transfers in simulations is preserved in experiments, in part because the RF field amplitude in PR5 is only 2.5 times the MAS frequency so that relatively low 1H decoupling powers are required. Experiments on a microcrystalline sample of the β1 immunoglobulin binding domain of protein G demonstrate an average enhancement factor of 1.6 for 13Cα → 13Cβ polarization transfers, compared to the standard 13C-13C spin-diffusion method, implying a two-fold time saving in relevant 2D and 3D experiments.
Collapse
Affiliation(s)
- Zhengfeng Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Hui Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Jing Deng
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA
| | - Jun Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
| |
Collapse
|
8
|
Grüninger H, Schmutzler A, Siegel R, Armstrong K, Frost DJ, Senker J. Quantitative description of 1H SQ and DQ coherences for the hydroxyl disorder within hydrous ringwoodite. Phys Chem Chem Phys 2018; 20:15098-15105. [PMID: 29799049 DOI: 10.1039/c8cp00863a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton-containing point defects in solid materials are important for a variety of properties ranging from ionic transport over thermal conductivity up to compressibility. Ultrafast magic-angle spinning techniques nowadays offer high-resolution solid-state NMR spectra, even for 1H, and thus open up possibilities to study the underlying defect chemistry. Nevertheless, disorder within such defects again leads to heavy spectral overlap of 1H resonances, which prevents quantitative analysis of defect concentrations, if several defect types are present. Here, we present a strategy to overcome this limitation by simulating the 1H lineshape as well as 1H-1H double-quantum buildup curves, which we then validate against the experimental data in a joint cost function. To mimic the local structural disorder, we use molecular dynamics simulations at the DFT level. It turned out to be advantageous for the joint refinement to put the computational effort into the structural optimisation to derive accurate proton positions and to use empirical correlations for the relation between isotropic and anisotropic 1H chemical shifts and structural elements. The expressiveness of this approach is demonstrated on ringwoodite's (γ-Mg2SiO4) OH defect chemistry containing four different defect types in octahedral and tetrahedral voids with both pure Mg and mixed Si and Mg cation environments. Still, we determine the ratio for each defect type with an accuracy of about 5% as a result of the minimization of the joint cost function. We expect that our approach is generally applicable for local proton disorder and might prove to be a valuable alternative to the established AIRSS and Monte Carlo methods, respectively.
Collapse
Affiliation(s)
- Helen Grüninger
- Anorganische Chemie III, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
| | | | | | | | | | | |
Collapse
|
9
|
Najdanova M, Gräsing D, Alia A, Matysik J. Analysis of the Electronic Structure of the Special Pair of a Bacterial Photosynthetic Reaction Center by 13 C Photochemically Induced Dynamic Nuclear Polarization Magic-Angle Spinning NMR Using a Double-Quantum Axis. Photochem Photobiol 2017; 94:69-80. [PMID: 28746728 DOI: 10.1111/php.12812] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/04/2017] [Indexed: 11/28/2022]
Abstract
The origin of the functional symmetry break in bacterial photosynthesis challenges since several decades. Although structurally very similar, the two branches of cofactors in the reaction center (RC) protein complex act very differently. Upon photochemical excitation, an electron is transported along one branch, while the other remains inactive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) 13 C NMR revealed that the two bacteriochlorophyll cofactors forming the "Special Pair" donor dimer are already well distinguished in the electronic ground state. These previous studies are relying solely on 13 C-13 C correlation experiments as radio-frequency-driven recoupling (RFDR) and dipolar-assisted rotational resonance (DARR). Obviously, the chemical-shift assignment is difficult in a dimer of tetrapyrrole macrocycles, having eight pyrrole rings of similar chemical shifts. To overcome this problem, an INADEQUATE type of experiment using a POST C7 symmetry-based approach is applied to selectively isotope-labeled bacterial RC of Rhodobacter (R.) sphaeroides wild type (WT). We, therefore, were able to distinguish unresolved sites of the macromolecular dimer. The obtained chemical-shift pattern is in-line with a concentric assembly of negative charge within the common center of the Special Pair supermolecule in the electronic ground state.
Collapse
Affiliation(s)
- Marija Najdanova
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
| | - Daniel Gräsing
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
| | - A Alia
- Institute of Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany.,Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Jörg Matysik
- Institute of Analytical Chemistry, University of Leipzig, Leipzig, Germany
| |
Collapse
|
10
|
Grüninger H, Armstrong K, Greim D, Boffa-Ballaran T, Frost DJ, Senker J. Hidden Oceans? Unraveling the Structure of Hydrous Defects in the Earth's Deep Interior. J Am Chem Soc 2017; 139:10499-10505. [PMID: 28683554 DOI: 10.1021/jacs.7b05432] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-pressure silicates making up the main proportion of the earth's interior can incorporate a significant amount of water in the form of OH defects. Generally, they are charge balanced by removing low-valent cations such as Mg2+. By combining high-resolution multidimensional single- and double-quantum 1H solid-state NMR spectroscopy with density functional theory calculations, we show that, for ringwoodite (γ-Mg2SiO4), additionally, Si4+ vacancies are formed, even at a water content as low as 0.1 wt %. They are charge balanced by either four protons or one Mg2+ and two protons. Surprisingly, also a significant proportion of coupled Mg and Si vacancies are present. Furthermore, all defect types feature a pronounced orientational disorder of the OH groups, which results in a significant range of OH···O bond distributions. As such, we are able to present unique insight into the defect chemistry of ringwoodite's spinel structure, which not only accounts for a potentially large fraction of the earth's entire water budget, but will also control transport properties in the mantle. We expect that our results will even impact other hydrous spinel-type materials, helping to understand properties such as ion conduction and heterogeneous catalysis.
Collapse
Affiliation(s)
- Helen Grüninger
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Katherine Armstrong
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Dominik Greim
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Tiziana Boffa-Ballaran
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Daniel J Frost
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Jürgen Senker
- Anorganische Chemie III and ‡Bayerisches Geoinstitut, University of Bayreuth , Universitätsstrasse 30, 95447 Bayreuth, Germany
| |
Collapse
|
11
|
Yan ZB, Brouwer DH, Goward GR. 19F Double Quantum NMR Spectroscopy: A Tool for Probing Dynamics in Proton-Conducting Fluorinated Polymer Materials. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01291] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Z. Blossom Yan
- Department
of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada L8S 4M1
| | - Darren H. Brouwer
- Department
of Chemistry, Redeemer University College, Ancaster, Ontario, Canada L9K 1J4
| | - Gillian R. Goward
- Department
of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada L8S 4M1
| |
Collapse
|
12
|
Teymoori G, Pahari B, Edén M. Low-power broadband homonuclear dipolar recoupling in MAS NMR by two-fold symmetry pulse schemes for magnetization transfers and double-quantum excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 261:205-20. [PMID: 26515279 DOI: 10.1016/j.jmr.2015.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/31/2015] [Accepted: 09/07/2015] [Indexed: 05/28/2023]
Abstract
We provide an experimental, numerical, and high-order average Hamiltonian evaluation of an open-ended series of homonuclear dipolar recoupling sequences, SR [Formula: see text] with p=1,2,3,…. While operating at a very low radio-frequency (rf) power, corresponding to a nutation frequency of 1/2 of the magic-angle spinning (MAS) rate (ωnut=ωr/2), these recursively generated double-quantum (2Q) dipolar recoupling schemes offer a progressively improved compensation to resonance offsets and rf inhomogeneity for increasing pulse-sequence order p. The excellent recoupling robustness to these experimental obstacles, as well as to CSA, is demonstrated for 2Q filtering (2QF) experiments and for driving magnetization transfers in 2D NMR correlation spectroscopy, where the sequences may provide either double or zero quantum dipolar Hamiltonians during mixing. Experimental and numerical demonstrations, which mostly target conditions of "ultra-fast" MAS (≳50kHz) and high magnetic fields, are provided for recoupling of (13)C across a wide range of isotropic and anisotropic chemical shifts, as well as dipolar coupling constants, encompassing [2,3-(13)C2]alanine, [1,3-(13)C2]alanine, diammonium [1,4-(13)C2]fumarate, and [U-(13)C]tyrosine. When compared at equal power levels, a superior performance is observed for the SR [Formula: see text] sequences with p⩾3 relative to existing and well-established 2Q recoupling techniques. At ultra-fast MAS, proton decoupling is redundant during the homonuclear dipolar recoupling of dilute spins in organic solids, which renders the family of SR [Formula: see text] schemes the first efficient 2Q recoupling option for general applications, such as 2Q-1Q correlation NMR and high-order multiple-quantum excitation, under truly low-power rf conditions.
Collapse
Affiliation(s)
- Gholamhasan Teymoori
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bholanath Pahari
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Mattias Edén
- Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
| |
Collapse
|
13
|
Zehe CS, Siegel R, Senker J. Influence of proton coupling on symmetry-based homonuclear (19)F dipolar recoupling experiments. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 65:122-131. [PMID: 25572924 DOI: 10.1016/j.ssnmr.2014.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 12/03/2014] [Accepted: 12/05/2014] [Indexed: 06/04/2023]
Abstract
We study the efficiency of two symmetry based homonuclear (19)F double-quantum recoupling sequences for moderate (R142(6)) and ultra-fast (R144(5)) MAS under the influence of strong (1)H-(1)H and (1)H-(19)F dipolar interactions and (1)H continuous wave decoupling. Simulations based on various spin systems derived from the organic solid 1,3,5-tris(2-fluoro-2-methylpropionylamino)benzene (F-BTA), used as a model system, reveal that the strong-decoupling limit is not accessible even for moderate spinning speeds. Additionally, for the no-decoupling limit improved DQ efficiencies are predicted for both moderate and ultra-fast MAS. Strong perturbations of build-up curves can be avoided by additional stabilisation through supercycling. Additional (1)H cw decoupling during (19)F recoupling rapidly reduces the maximum DQ efficiency when deviating from the no-decoupling limit. These effects were confirmed by experimental data on F-BTA. For moderate spinning the influence of (1)H-(1)H and (1)H-(19)F couplings is markedly stronger compared to ultra-fast MAS. For the latter case those influences reduce to a constant scaling if only short excitation times up to the first minimum are taken into account. Based on this analysis the experimental build-up curves of 1,3,5-tris(2-fluoro-2-methylpropionylamino)benzene can be refined with homonuclear (19)F spin systems which allow to probe even subtle structural differences for the fluorine atoms of F-BTA.
Collapse
Affiliation(s)
- Christoph S Zehe
- Inorganic Chemistry III, University of Bayreuth, 95447 Bayreuth, Germany
| | - Renée Siegel
- Inorganic Chemistry III, University of Bayreuth, 95447 Bayreuth, Germany
| | - Jürgen Senker
- Inorganic Chemistry III, University of Bayreuth, 95447 Bayreuth, Germany.
| |
Collapse
|
14
|
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy is a well-established method for the investigation of various types of porous materials. During the past decade, metal–organic frameworks have attracted increasing research interest. Solid-state NMR spectroscopy has rapidly evolved into an important tool for the study of the structure, dynamics and flexibility of these materials, as well as for the characterization of host–guest interactions with adsorbed species such as xenon, carbon dioxide, water, and many others. The present review introduces and highlights recent developments in this rapidly growing field.
Collapse
|
15
|
Low-power broadband homonuclear dipolar recoupling without decoupling: Double-quantum 13C NMR correlations at very fast magic-angle spinning. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.07.053] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
16
|
Edén M, Lo AYH. Supercycled symmetry-based double-quantum dipolar recoupling of quadrupolar spins in MAS NMR: I. Theory. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 200:267-279. [PMID: 19648039 DOI: 10.1016/j.jmr.2009.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 07/04/2009] [Accepted: 07/08/2009] [Indexed: 05/28/2023]
Abstract
Using average Hamiltonian (AH) theory, we analyze recently introduced homonuclear dipolar recoupling pulse sequences for exciting central-transition double-quantum coherences (2QC) between half-integer spin quadrupolar nuclei undergoing magic-angle-spinning. Several previously observed differences among the recoupling schemes concerning their compensation to resonance offsets and radio-frequency (rf) inhomogeneity may qualitatively be rationalized by an AH analysis up to third perturbation order, despite its omission of first-order quadrupolar interactions. General aspects of the engineering of 2Q-recoupling pulse sequences applicable to half-integer spins are discussed, emphasizing the improvements offered from a diversity of supercycles providing enhanced suppression of undesirable AH cross-terms between resonance offsets and rf amplitude errors.
Collapse
Affiliation(s)
- Mattias Edén
- Physical Chemistry Division, Stockholm University, Stockholm, Sweden.
| | | |
Collapse
|
17
|
Herbst C, Herbst J, Leppert J, Ohlenschläger O, Görlach M, Ramachandran R. Numerical design of RN(n)(nu) symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies. JOURNAL OF BIOMOLECULAR NMR 2009; 44:235-244. [PMID: 19557520 DOI: 10.1007/s10858-009-9335-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 06/03/2009] [Indexed: 05/28/2023]
Abstract
An approach for the efficient implementation of RN(n)(nu) symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN(n)(nu) symmetry involve the repeated application of the pulse sandwich {R(phi)R(-phi)}, corresponding to a propagator U(RF) = exp(-i4phiI(z)), where phi = pinu/N and R is typically a pulse that rotates the nuclear spins through 180 degrees about the x-axis. In this study, broadband, phase-modulated 180 degrees pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN(n)(nu) symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13C-13C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here.
Collapse
Affiliation(s)
- Christian Herbst
- Research group Biomolecular NMR spectroscopy, Leibniz Institute for Age Research, Fritz Lipmann Institute, 07745 Jena, Germany
| | | | | | | | | | | |
Collapse
|
18
|
Mafra L, Siegel R, Fernandez C, Schneider D, Aussenac F, Rocha J. High-resolution 1H homonuclear dipolar recoupling NMR spectra of biological solids at MAS rates up to 67 kHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 199:111-114. [PMID: 19410491 DOI: 10.1016/j.jmr.2009.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/25/2009] [Accepted: 04/09/2009] [Indexed: 05/27/2023]
Abstract
Two-dimensional (1)H homonuclear correlation NMR spectra of solids of biological interest have been recorded at high magnetic fields (14.1 and 18.8 T) and MAS rates up to 67 kHz, using RN(n)(nu) symmetry-based homonuclear recoupling and CRAMPS decoupling; this method affords exceptional spectral resolution and is well suited to probe (1)H-(1)H proximities in powdered solids.
Collapse
Affiliation(s)
- Luis Mafra
- Department of Chemistry, University of Aveiro, CICECO, Campus de Santiago, 3810-193 Aveiro, Portugal.
| | | | | | | | | | | |
Collapse
|
19
|
|
20
|
Kristiansen PE, Carravetta M, van Beek JD, Lai WC, Levitt MH. Theory and applications of supercycled symmetry-based recoupling sequences in solid-state nuclear magnetic resonance. J Chem Phys 2006; 124:234510. [PMID: 16821932 DOI: 10.1063/1.2205857] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present the theoretical principles of supercycled symmetry-based recoupling sequences in solid-state magic-angle-spinning NMR. We discuss the construction procedure of the SR26 pulse sequence, which is a particularly robust sequence for double-quantum homonuclear dipole-dipole recoupling. The supercycle removes destructive higher-order average Hamiltonian terms and renders the sequence robust over long time intervals. We demonstrate applications of the SR26 sequence to double-quantum spectroscopy, homonuclear spin counting, and determination of the relative orientations of chemical shift anisotropy tensors.
Collapse
Affiliation(s)
- Per Eugen Kristiansen
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041-Blindern, 0316 Oslo, Norway
| | | | | | | | | |
Collapse
|
21
|
Marin-Montesinos I, Brouwer DH, Antonioli G, Lai WC, Brinkmann A, Levitt MH. Heteronuclear decoupling interference during symmetry-based homonuclear recoupling in solid-state NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 177:307-17. [PMID: 16169757 DOI: 10.1016/j.jmr.2005.07.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/13/2005] [Accepted: 07/14/2005] [Indexed: 05/04/2023]
Abstract
We examine the influence of continuous-wave heteronuclear decoupling on symmetry-based double-quantum homonuclear dipolar recoupling, using experimental measurements, numerical simulations, and average Hamiltonian theory. There are two distinct regimes in which the heteronuclear interference effects are minimized. The first regime utilizes a moderate homonuclear recoupling field and a strong heteronuclear decoupling field; the second regime utilizes a strong homonuclear recoupling field and a weak or absent heteronuclear decoupling field. The second regime is experimentally accessible at moderate or high magic-angle-spinning frequencies and is particularly relevant for many realistic applications of solid-state NMR recoupling experiments to organic or biological materials.
Collapse
|
22
|
Edén M, Brinkmann A. Triple-quantum dynamics in multiple-spin systems undergoing magic-angle spinning: application to 13C homonuclear correlation spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 173:259-279. [PMID: 15780918 DOI: 10.1016/j.jmr.2004.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Revised: 12/15/2004] [Indexed: 05/24/2023]
Abstract
We analyze the multiple-quantum dynamics governed by a new homonuclear recoupling strategy effecting an average dipolar Hamiltonian comprising three-spin triple-quantum operators (e.g., S(p)+S(q)+S(r)+) under magic-angle spinning conditions. Analytical expressions are presented for polarization transfer processes in systems of three and four coupled spins-1/2 subject to triple-quantum filtration (3QF), and high-order multiple-quantum excitation is investigated numerically in moderately large clusters, comprising up to seven spins. This recoupling approach gives highly efficient excitation of triple-quantum coherences: ideally, up to 67% of the initial polarization may be recovered by 3QF in three-spin systems in polycrystalline powders. Two homonuclear 2D correlation strategies are demonstrated experimentally on powders of uniformly 13C-labeled alanine and tyrosine: the first correlates the single-quantum spectrum in the first dimension with the corresponding 3QF spectrum along the other. The second protocol correlates triple-quantum coherences with their corresponding single-quantum coherences within triplets of coupled spins.
Collapse
Affiliation(s)
- Mattias Edén
- Physical Chemistry Division, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
| | | |
Collapse
|
23
|
Heise H, Seidel K, Etzkorn M, Becker S, Baldus M. 3D NMR spectroscopy for resonance assignment and structure elucidation of proteins under MAS: novel pulse schemes and sensitivity considerations. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 173:64-74. [PMID: 15705514 DOI: 10.1016/j.jmr.2004.11.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Revised: 11/15/2004] [Indexed: 05/24/2023]
Abstract
Two types of 3D MAS NMR experiments are introduced, which combine standard (NC,CC) transfer schemes with (1H,1H) mixing to simultaneously detect connectivities and structural constraints of uniformly 15N,13C-labeled proteins with high spectral resolution. The homonuclear CCHHC and CCC experiments are recorded with one double-quantum evolution dimension in order to avoid a cubic diagonal in the spectrum. Depending on the second transfer step, spin systems or proton-proton contacts can be determined with reduced spectral overlap. The heteronuclear NHHCC experiment encodes NH-HC proton-proton interactions, which are indicative for the backbone conformation of the protein. The third dimension facilitates the identification of the amino acid spin system. Experimental results on U-[15N,13C]valine and U-[15N,13C]ubiquitin demonstrate their usefulness for resonance assignments and for the determination of structural constraints. Furthermore, we give a detailed analysis of alternative multidimensional sampling schemes and their effect on sensitivity and resolution.
Collapse
Affiliation(s)
- Henrike Heise
- Department for NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany.
| | | | | | | | | |
Collapse
|
24
|
Brinkmann A, Edén M. Second order average Hamiltonian theory of symmetry-based pulse schemes in the nuclear magnetic resonance of rotating solids: Application to triple-quantum dipolar recoupling. J Chem Phys 2004; 120:11726-45. [PMID: 15268208 DOI: 10.1063/1.1738102] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The average Hamiltonian theory (AHT) of several classes of symmetry-based radio-frequency pulse sequences is developed to second order, allowing quantitative analyses of a wide range of recoupling and decoupling applications in magic-angle-spinning solid state nuclear magnetic resonance. General closed analytical expressions are presented for a cross term between any two interactions recoupled to second order AHT. We classify them into different categories and show that some properties of the recoupling pulse sequence may be predicted directly from this classification. These results are applied to examine a novel homonuclear recoupling strategy, effecting a second order average dipolar Hamiltonian comprising trilinear triple quantum (3Q) spin operators. We discuss general features and design principles of such 3Q recoupling sequences and demonstrate by numerical simulations and experiments that they provide more efficient excitation of (13)C 3Q coherences compared to previous techniques. We passed up to 15% of the signal through a state of 3Q coherence in rotating powders of uniformly (13)C-labeled alanine and tyrosine. Second order recoupling-based (13)C homonuclear 3Q correlation spectroscopy is introduced and demonstrated on tyrosine.
Collapse
Affiliation(s)
- Andreas Brinkmann
- Physical Chemistry/Solid State NMR, NSRIM Center, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
| | | |
Collapse
|
25
|
Kristiansen PE, Carravetta M, Lai WC, Levitt MH. A robust pulse sequence for the determination of small homonuclear dipolar couplings in magic-angle spinning NMR. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.03.075] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
26
|
Hughes CE, Luca S, Baldus M. Radio-frequency driven polarization transfer without heteronuclear decoupling in rotating solids. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.01.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
27
|
Schmedt auf der Günne J. Distance measurements in spin-1/2 systems by 13C and 31P solid-state NMR in dense dipolar networks. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2003; 165:18-32. [PMID: 14568514 DOI: 10.1016/s1090-7807(03)00242-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this article solid-state NMR methods for the determination of internuclear dipole-dipole couplings between homonuclear spin-1/2 nuclei are presented. They are suitable for relatively dense dipolar networks which are still dominated by 2-spin interactions. C-/R-symmetry theory is applied to create a double-quantum average Hamiltonian using phase-modulated radio-frequency irradiation and magic-angle sample-rotation. Symmetry derived pulse sequences with improved compensation against chemical shift anisotropies were found assuming a small isotropic chemical shift difference and using numerical calculations of the spin dynamics. Moreover it is shown that a constant time procedure can be used to acquire reliable double-quantum build-up curves even in systems in which damping obscures oscillations in their symmetric build-up curve. This technique is demonstrated on four crystalline model compounds with 31P and 13C spin systems typical for inorganic and biological applications. Comparison to crystal structure data indicates that the distances derived this way from 31P and 13C double-quantum NMR carry only small systematic errors caused for example by anisotropic J-coupling, dipolar contributions from adjacent spins and relaxation.
Collapse
|
28
|
Matsuki Y, Akutsu H, Fujiwara T. Band-selective recoupling of homonuclear double-quantum dipolar interaction with a generalized composite 0 degrees pulse: application to 13C aliphatic region-selective magnetization transfer in solids. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2003; 162:54-66. [PMID: 12762983 DOI: 10.1016/s1090-7807(02)00191-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recoupling of homonuclear double quantum (DQ)-dipolar interactions is a useful technique for the structural analysis of molecules in solids. We have designed a series of elemental 0 degrees pulses for the recoupling sequences with the rf phase rotation about the z-axis, known as CN. The proposed 0 degrees pulses whose total flip angle >/=360 degrees provide spin rotation vectors in the xy-plane. Thus, the residual spin rotation can be canceled by rf phase rotation about the z-axis. An analysis by the coherent averaging theory showed that effective bandwidths of the recoupling sequences are limited not by the reduction in the dipolar scaling factor but by the increase in the residual spin rotation due to offset. A CN sequence with these elemental pulses provides an effective bandwidth of DQ-dipolar recoupling from ca. 0.5nu(R) to 4nu(R) for numerical simulations. Here, nu(R) is the sample spinning frequency. The 0 degrees pulses were applied to band-selective recoupling for the magnetization transfer in uniformly 13C-labeled molecules. Narrow-band recoupling enhances the magnetization transfer between spins within the effective range by decoupling the dipolar interactions between spins one of which is outside the range. The narrow band operation reduces rf field strength, which improves the CH decoupling. Increases in signal intensities by the use of the proposed 0 degrees pulses are experimentally shown for 13C-labeled amino acids.
Collapse
Affiliation(s)
- Yoh Matsuki
- Division of Molecular Biophysics, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, 565-0871, Suita, Japan
| | | | | |
Collapse
|