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Pradhan BL, Lodhi L, Dey KK, Ghosh M. Analyzing atomic scale structural details and nuclear spin dynamics of four macrolide antibiotics: erythromycin, clarithromycin, azithromycin, and roxithromycin. RSC Adv 2024; 14:17733-17770. [PMID: 38832242 PMCID: PMC11145140 DOI: 10.1039/d4ra00718b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 05/26/2024] [Indexed: 06/05/2024] Open
Abstract
The current investigation centers on elucidating the intricate molecular architecture and dynamic behavior of four macrolide antibiotics, specifically erythromycin, clarithromycin, azithromycin, and roxithromycin, through the application of sophisticated solid-state nuclear magnetic resonance (SSNMR) methodologies. We have measured the principal components of chemical shift anisotropy (CSA) parameters, and the site-specific spin-lattice relaxation time at carbon nuclei sites. To extract the principal components of CSA parameters, we have employed 13C 2DPASS CP-MAS SSNMR experiments at two different values of magic angle spinning (MAS) frequencies, namely 2 kHz and 600 Hz. Additionally, the spatial correlation between 13C and 1H nuclei has been investigated using 1H-13C frequency switched Lee-Goldburg heteronuclear correlation (FSLGHETCOR) experiment at a MAS frequency of 24 kHz. Our findings demonstrate that the incorporation of diverse functional groups, such as the ketone group and oxime group with the lactone ring, exerts notable influences on the structure and dynamics of the macrolide antibiotic. In particular, we have observed a significant decrease in the spin-lattice relaxation time of carbon nuclei residing on the lactone ring, desosamine, and cladinose in roxithromycin, compared to erythromycin. Overall, our findings provide detailed insight into the relationship between the structure and dynamics of macrolide antibiotics, which is eventually correlated with their biological activity. This knowledge can be utilized to develop new and more effective drugs by providing a rational basis for drug discovery and design.
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Affiliation(s)
- Bijay Laxmi Pradhan
- Physics Section, Mahila Maha Vidyalaya, Banaras Hindu University Varanasi-221005 Uttar-Pradesh India
- Department of Physics, Institute of Science, Banaras Hindu University Varanasi-221005 Uttar-Pradesh India
| | - Lekhan Lodhi
- Department of Zoology, Dr Harisingh Gour Central University Sagar-470003 Madhya-Pradesh India
| | - Krishna Kishor Dey
- Department of Physics, Dr Harisingh Gour Central University Sagar-470003 Madhya-Pradesh India
| | - Manasi Ghosh
- Physics Section, Mahila Maha Vidyalaya, Banaras Hindu University Varanasi-221005 Uttar-Pradesh India
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2
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Southern SA, Liu DJ, Chatterjee P, Li Y, Perras FA. 1H chemical shift anisotropy: a high sensitivity solid-state NMR dynamics probe for surface studies? Phys Chem Chem Phys 2023; 25:5348-5360. [PMID: 36399032 DOI: 10.1039/d2cp04406d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Dynamics play significant roles in chemistry and biochemistry-molecular motions impact both large- and small-scale chemical reactions in addition to biochemical processes. In many systems, including heterogeneous catalysts, the characterization of dynamics remains a challenge. The most common approaches involve the solid-state NMR measurement of anisotropic interactions, in particular 2H quadrupolar coupling and 1H-X dipolar coupling, which generally require isotope enrichment. Due to the high sensitivity of 1H NMR, 1H chemical shift anisotropy (CSA) is a particularly enticing, and underexplored, dynamics probe. We carried out 1H CSA and 1H-13C dipolar coupling measurements in a series of model supported complexes to understand how 1H CSA can be leveraged to gain dynamic information for heterogeneous catalysts. Mathematical descriptions are given for the dynamic averaging of the CSA tensor, and its dependence on orientation and asymmetry. The variability of the orientation of the tensor in the molecular frame, in addition to its magnitude and asymmetry, negatively impacts attempts to extract quantitative dynamic information. Nevertheless, 1H CSA measurements can reveal useful qualitative insights into the motions of a particularly dilute site, such as from a surface species.
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Affiliation(s)
- Scott A Southern
- Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, IA 50014, USA.
| | - Da-Jiang Liu
- Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, IA 50014, USA.
| | - Puranjan Chatterjee
- Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, IA 50014, USA. .,Department of Chemistry, Iowa State University, Ames, IA 50014, USA
| | - Yuting Li
- Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, IA 50014, USA.
| | - Frédéric A Perras
- Division of Chemical and Biological Sciences, Ames National Laboratory, Ames, IA 50014, USA.
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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.
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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
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Liang L, Ji Y, Chen K, Gao P, Zhao Z, Hou G. Solid-State NMR Dipolar and Chemical Shift Anisotropy Recoupling Techniques for Structural and Dynamical Studies in Biological Systems. Chem Rev 2022; 122:9880-9942. [PMID: 35006680 DOI: 10.1021/acs.chemrev.1c00779] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
With the development of NMR methodology and technology during the past decades, solid-state NMR (ssNMR) has become a particularly important tool for investigating structure and dynamics at atomic scale in biological systems, where the recoupling techniques play pivotal roles in modern high-resolution MAS NMR. In this review, following a brief introduction on the basic theory of recoupling in ssNMR, we highlight the recent advances in dipolar and chemical shift anisotropy recoupling methods, as well as their applications in structural determination and dynamical characterization at multiple time scales (i.e., fast-, intermediate-, and slow-motion). The performances of these prevalent recoupling techniques are compared and discussed in multiple aspects, together with the representative applications in biomolecules. Given the recent emerging advances in NMR technology, new challenges for recoupling methodology development and potential opportunities for biological systems are also discussed.
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Affiliation(s)
- 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
| | - 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
| | - Kuizhi Chen
- 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
| | - Pan Gao
- 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
| | - Zhenchao Zhao
- 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
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Shcherbakov AA, Medeiros-Silva J, Tran N, Gelenter MD, Hong M. From Angstroms to Nanometers: Measuring Interatomic Distances by Solid-State NMR. Chem Rev 2021; 122:9848-9879. [PMID: 34694769 DOI: 10.1021/acs.chemrev.1c00662] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Internuclear distances represent one of the main structural constraints in molecular structure determination using solid-state NMR spectroscopy, complementing chemical shifts and orientational restraints. Although a large number of magic-angle-spinning (MAS) NMR techniques have been available for distance measurements, traditional 13C and 15N NMR experiments are inherently limited to distances of a few angstroms due to the low gyromagnetic ratios of these nuclei. Recent development of fast MAS triple-resonance 19F and 1H NMR probes has stimulated the design of MAS NMR experiments that measure distances in the 1-2 nm range with high sensitivity. This review describes the principles and applications of these multiplexed multidimensional correlation distance NMR experiments, with an emphasis on 19F- and 1H-based distance experiments. Representative applications of these long-distance NMR methods to biological macromolecules as well as small molecules are reviewed.
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Affiliation(s)
- Alexander A Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - João Medeiros-Silva
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - Nhi Tran
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - Martin D Gelenter
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139, United States
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Kobayashi T, Perras FA, Nishiyama Y. Determination of the chemical shift tensor anisotropy and asymmetry of strongly dipolar coupled protons under fast MAS. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2021; 114:101743. [PMID: 34153880 DOI: 10.1016/j.ssnmr.2021.101743] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
Orientationally-dependent interactions such as dipolar coupling, quadrupolar coupling, and chemical shift anisotropy (CSA) contain a wealth of spatial information that can be used to elucidate molecular conformations and dynamics. To determine the sign of the chemical shift tensor anisotropy parameter (δaniso), both the |m| = 1 and |m| = 2 components of the CSA need to be symmetry allowed, while the recoupling of the |m| = 1 term is accompanied with the reintroduction of homonuclear dipolar coupling components. Therefore, previously suggested sequences which solely recouple the |m| = 2 term cannot determine the sign a 1H's δaniso in a densely-coupled network. In this study, we demonstrate the CSA recoupling of strongly dipolar coupled 1H spins using the Cnn1(9003601805400360180900) sequence. This pulse scheme recouples both the |m| = 1 and |m| = 2 CSA terms but the scaling factors for the homonuclear dipolar coupling terms are zeroed. Consequently, the sequence is sensitive to the sign of δaniso but is not influenced by homonuclear dipolar interactions.
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Affiliation(s)
- Takeshi Kobayashi
- U.S. DOE, Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States.
| | - Frédéric A Perras
- U.S. DOE, Ames Laboratory, Iowa State University, Ames, IA, 50011-3020, United States
| | - Yusuke Nishiyama
- RIKEN-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa, 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo, 196-8558, Japan
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7
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Design, synthesis and HR – MAS NMR characterization of molecular imprinted polymers with emerging contaminants templates. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.117860] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Hodgkinson P. NMR crystallography of molecular organics. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 118-119:10-53. [PMID: 32883448 DOI: 10.1016/j.pnmrs.2020.03.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/25/2020] [Accepted: 03/13/2020] [Indexed: 06/11/2023]
Abstract
Developments of NMR methodology to characterise the structures of molecular organic structures are reviewed, concentrating on the previous decade of research in which density functional theory-based calculations of NMR parameters in periodic solids have become widespread. With a focus on demonstrating the new structural insights provided, it is shown how "NMR crystallography" has been used in a spectrum of applications from resolving ambiguities in diffraction-derived structures (such as hydrogen atom positioning) to deriving complete structures in the absence of diffraction data. As well as comprehensively reviewing applications, the different aspects of the experimental and computational techniques used in NMR crystallography are surveyed. NMR crystallography is seen to be a rapidly maturing subject area that is increasingly appreciated by the wider crystallographic community.
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Affiliation(s)
- Paul Hodgkinson
- Department of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, UK.
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Zhang R, Hong YL, Ravula T, Nishiyama Y, Ramamoorthy A. High-resolution proton-detected MAS experiments on self-assembled diphenylalanine nanotubes enabled by fast MAS and high magnetic field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 313:106717. [PMID: 32240957 DOI: 10.1016/j.jmr.2020.106717] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 06/11/2023]
Abstract
The advent of ultrahigh magnetic field and fast magic-angle-spinning (MAS) probe technology has led to dramatically enhanced spectral resolution and sensitivity in solid-state NMR spectroscopy. In particular, proton-based multidimensional solid-state NMR techniques have become feasible to investigate the structure and dynamics at atomic resolution, due to the increased chemical shift span and spectral resolution. Herein, the benefits of faster MAS and higher magnetic field are demonstrated on a self-assembled diphenylalanine (Phe-Phe) nanomaterial. Proton-detected 2D 1H/1H single-quantum/single-quantum (SQ/SQ) correlation, double-quantum/single-quantum (DQ/SQ) correlation, and 1H chemical shift anisotropy/chemical shift (CSA/CS) correlation spectra obtained at two different spinning speeds (60 and 100 kHz) and two different magnetic fields (600 and 900 MHz) are reported. The dramatic enhancement of proton spectral resolution achieved with the use of a 900 MHz magnetic field and 100 kHz MAS is remarkable and enabled the measurement of proton CSA tensors, which will be useful to better understand the self-assembled structures of Phe-Phe nanotubes. We also show through numerical simulations that the unaveraged proton-proton dipolar couplings can result in broadening of CSA lines, leading to inaccurate determination of CSA tensors of protons. Thus, our results clearly show the insufficiency of a 600 MHz magnetic field to resolve 1H spectra lines and the inability of a moderate spinning speed of 60 kHz to completely suppress 1H-1H dipolar couplings, which further justify the pursuit of ultrahigh magnetic field beyond 1 GHz and ultrafast MAS beyond 100 kHz.
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Affiliation(s)
- Rongchun Zhang
- Biophysics and Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA.
| | - You-Lee Hong
- Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan; Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Institute for Advanced Study, and AIST-Kyoto University Chemical Energy Material Open Innovation Laboratory (ChEM-OIL), Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
| | - Thirupathi Ravula
- Biophysics and Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Yusuke Nishiyama
- Nano-Crystallography Unit, RIKEN-JEOL Collaboration Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan; NMR Science and Development Division, RIKEN SPring-8 Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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Mann SK, Pham TN, McQueen LL, Lewandowski JR, Brown SP. Revealing Intermolecular Hydrogen Bonding Structure and Dynamics in a Deep Eutectic Pharmaceutical by Magic-Angle Spinning NMR Spectroscopy. Mol Pharm 2020; 17:622-631. [PMID: 31887061 PMCID: PMC7007282 DOI: 10.1021/acs.molpharmaceut.9b01075] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Liquid forms of pharmaceuticals (ionic liquids and deep eutectic solvents) offer a number of potential advantages over solid-state drugs; a key question is the role of intermolecular hydrogen bonding interactions in enabling membrane transport. Characterization is challenging since high sample viscosities, typical of liquid pharmaceutical formulations, hamper the use of conventional solution NMR at ambient temperature. Here, we report the application of magic-angle spinning (MAS) NMR spectroscopy to the deep eutectic pharmaceutical, lidocaine ibuprofen. Using variable temperature MAS NMR, the neat system, at a fixed molar ratio, can be studied over a wide range of temperatures, characterized by changing mobility, using a single experimental setup. Specific intermolecular hydrogen bonding interactions are identified by two-dimensional 1H-1H NOESY and ROESY MAS NMR experiments. Hydrogen-bonding dynamics are quantitatively determined by following the chemical exchange process between the labile protons by means of line-width analysis of variable temperature 1H MAS NMR spectra.
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Affiliation(s)
- Sarah K Mann
- Department of Physics , University of Warwick , Coventry CV4 7AL , U.K
| | - Tran N Pham
- GSK R&D , Stevenage , Hertfordshire SG1 2NY , U.K
| | - Lisa L McQueen
- GSK R&D , Collegeville , Pennsylvania 19426 , United States
| | | | - Steven P Brown
- Department of Physics , University of Warwick , Coventry CV4 7AL , U.K
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Malär AA, Dong S, Kehr G, Erker G, Meier BH, Wiegand T. Characterization of H 2 -Splitting Products of Frustrated Lewis Pairs: Benefit of Fast Magic-Angle Spinning. Chemphyschem 2019; 20:672-679. [PMID: 30663843 DOI: 10.1002/cphc.201900006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 01/19/2019] [Indexed: 11/09/2022]
Abstract
Proton spectroscopy in solid-state NMR on catalytic materials offers new opportunities in structural characterization, in particular of reaction products of catalytic reactions such as hydrogenation reactions. Unfortunately, the 1 H NMR line widths in magic-angle spinning solid-state spectra are often broadened by an incomplete averaging of 1 H-1 H dipolar couplings. We herein discuss two model compounds, namely the H2 -splitting products of two phosphane-borane Frustrated Lewis Pairs (FLPs), to study potentials and limitations of proton solid-state NMR experiments employing magic-angle spinning frequencies larger than 100 kHz at a static magnetic field strength of 20.0 T. The 1 H lines are homogeneously broadened as illustrated by spin-echo decay experiments. We study two structurally similar materials which however show significant differences in 1 H line widths which we explain by differences in their 1 H-1 H dipolar networks. We discuss the benefit of fast MAS experiments up to 110 kHz to detect the resonances of the H+ /H- pair in the hydrogenation products of FLPs.
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Affiliation(s)
- Alexander A Malär
- Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
| | - Shunxi Dong
- Organisch-Chemisches Institut, WWU Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerald Kehr
- Organisch-Chemisches Institut, WWU Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Gerhard Erker
- Organisch-Chemisches Institut, WWU Münster, Corrensstraße 40, 48149, Münster, Germany
| | - Beat H Meier
- Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
| | - Thomas Wiegand
- Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
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Pandey MK, Damron JT, Ramamoorthy A, Nishiyama Y. Proton-detected 3D 1H anisotropic/ 14N/ 1H isotropic chemical shifts correlation NMR under fast magic angle spinning on solid samples without isotopic enrichment. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 97:40-45. [PMID: 30623800 DOI: 10.1016/j.ssnmr.2018.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/25/2018] [Accepted: 12/26/2018] [Indexed: 06/09/2023]
Abstract
The chemical shift anisotropy (CSA) interaction of a nucleus is an important indicator of the local electronic environment particularly for the contributions arising from hydrogen (H)-bonding, electrostatic and π-π interactions. CSAs of protons bonded to nitrogen atoms are of significant interest due to their common role as H-bonding partners in many chemical, pharmaceutical and biological systems. Although very fast (∼100 kHz) magic angle sample spinning (MAS) experiments have enabled the measurement of proton CSAs directly from solids, due to a narrow chemical shift (CS) distribution, overlapping NH proton resonances are common and necessitate the introduction of an additional frequency dimension to the regular 2D 1H CSA/1H CS correlation method to achieve sufficient resolution. While this can be accomplished by using the isotropic shift frequency of 14N or 15N nuclei, the use of the naturally-abundant 14N nucleus avoids 15N isotopic labeling and therefore would be useful for a variety of solids. To this end, we propose a proton-detected 3D 1H CSA/14N/1H CS correlation method under fast MAS (90 kHz) to determine the CSA tensors of NH protons in samples without isotopic enrichment. Our experimental results demonstrate that the proposed 3D NMR experiment is capable of resolving the overlapping 1H resonances of amide (NH) groups through the 14N isotropic shift frequency dimension and enables the accurate measurement of site-specific 1H CSAs directly from powder samples under fast MAS conditions. In addition to the 3D 1H CSA/14N/1H CS experiment, an approach employing 14N-edited 2D 1H CSA/1H CS experiment is also demonstrated as an additional means to address spectral overlap of NH resonances with aliphatic and other proton resonances in solids.
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Affiliation(s)
- Manoj Kumar Pandey
- Indian Institute of Technology Ropar, Nangal Road, Rupnagar, 140001, Punjab, India.
| | - Joshua T Damron
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI, 48109-1055, USA
| | - Ayyalusamy Ramamoorthy
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI, 48109-1055, USA; Biophysics Program, University of Michigan, 930 N. University Ave., Ann Arbor, MI, 48109, USA
| | - Yusuke Nishiyama
- RIKEN-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa, 230-0045, Japan; JEOL RESONANCE Inc., Musashino, Akishima, Tokyo, 196-8558, Japan.
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