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Mishra SK, Suryaprakash N. Pure shift edited NMR methodologies for the extraction of Homo- and heteronuclear couplings with ultra-high resolution. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 136-137:1-60. [PMID: 37716754 DOI: 10.1016/j.pnmrs.2023.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 01/20/2023] [Accepted: 02/01/2023] [Indexed: 09/18/2023]
Abstract
The scalar couplings that result in the splitting of the signals in the NMR spectrum arise due to the interaction of the nuclear spins, whereby the spin polarization is transmitted through chemical bonds. The interaction strengths depend inter alia on the number of consecutive chemical bonds intervening between the two interacting spins and on the molecular conformation. The pairwise interaction of many spins in a molecule resulting in a complex spectrum poses a severe challenge to analyse the spectrum and hence the determination of magnitudes and signs of homo- and heteronuclear couplings. The problem is more severe in the analysis of 1H spectra than the spectra of most of the other nuclei due to the often very small chemical shift dispersion. As a consequence, the straightforward analysis and the accurate extraction of the coupling constants from the 1H spectrum of a complex spin system continues to remain a challenge, and often may be a formidable task. Over the years, the several pure shift-based one-dimensional and two-dimensional methodologies have been developed by workers in the field, which provide broadband homonuclear decoupling of proton spectra, removing the complexity but at the cost of the very informative scalar couplings. To circumvent this problem, several one-dimensional and two-dimensional NMR experiments have been developed for the determination of homonuclear and heteronuclear couplings (nJHX, where n = 1,2,3) while retaining the high resolution obtained by implementing pure shift strategies. This review attempts to summarize the extensive work reported by a large number of researchers over the years for the accurate determination of homo- and heteronuclear scalar couplings.
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Affiliation(s)
- Sandeep Kumar Mishra
- Department of Physics and NMR Research Centre, Indian Institute of Science Education and Research, Pune 411008, India.
| | - N Suryaprakash
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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2
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Raics M, Timári I, Szilágyi L, Gabius HJ, Kövér KE. Introducing 77Se NMR Spectroscopy to Analyzing Galectin -Ligand Interaction. Methods Mol Biol 2022; 2442:105-123. [PMID: 35320522 DOI: 10.1007/978-1-0716-2055-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Their emerging nature as multifunctional effectors explains the large interest to monitor glycan binding to galectins and to define bound-state conformer(s) of their ligands in solution. Basically, NMR spectroscopy facilitates respective experiments. Towards developing new and even better approaches for these purposes, extending the range of exploitable isotopes beyond 1H, 13C, and 15N offers promising perspectives. Having therefore prepared selenodigalactoside and revealed its bioactivity as galectin ligand, monitoring of its binding by 77Se NMR spectroscopy at a practical level becomes possible by setting up a 2D 1H, 77Se CPMG-HSQBMC experiment including CPMG-INEPT long-range transfer. This first step into applying 77Se as sensor for galectin binding substantiates its potential for screening relative to inhibitory potencies in compound mixtures and for achieving sophisticated epitope mapping. The documented strategic combination of synthetic carbohydrate chemistry and NMR spectroscopy prompts to envision to work with isotopically pure 77Se-containing β-galactosides and to build on the gained experience with 77Se by adding 19F as second sensor in doubly labeled glycosides.
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Affiliation(s)
- Mária Raics
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Debrecen, Hungary
| | - István Timári
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Debrecen, Hungary
| | - László Szilágyi
- Department of Organic Chemistry, University of Debrecen, Debrecen, Hungary
| | - Hans-Joachim Gabius
- Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, Munich, Germany.
| | - Katalin E Kövér
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Debrecen, Hungary.
- MTA-DE Molecular Recognition and Interaction Research Group, University of Debrecen, Debrecen, Hungary.
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3
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Elyashberg M, Argyropoulos D. Computer Assisted Structure Elucidation (CASE): Current and future perspectives. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:669-690. [PMID: 33197069 DOI: 10.1002/mrc.5115] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/31/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
The first efforts for the development of methods for Computer-Assisted Structure Elucidation (CASE) were published more than 50 years ago. CASE expert systems based on one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) data have matured considerably by now. The structures of a great number of complex natural products have been elucidated and/or revised using such programs. In this article, we discuss the most likely directions in which CASE will evolve. We act on the premise that a synergistic interaction exists between CASE, new NMR experiments, and methods of computational chemistry, which are continuously being improved. The new developments in NMR experiments (long-range correlation experiments, pure-shift methods, coupling constants measurement and prediction, residual dipolar couplings [RDCs]), and residual chemical shift anisotropies [RCSAs], evolution of density functional theory (DFT), and machine learning algorithms will have an influence on CASE systems and vice versa. This is true also for new techniques for chemical analysis (Atomic Force Microscopy [AFM], "crystalline sponge" X-ray analysis, and micro-Electron Diffraction [micro-ED]), which will be used in combination with expert systems. We foresee that CASE will be utilized widely and become a routine tool for NMR spectroscopists and analysts in academic and industrial laboratories. We believe that the "golden age" of CASE is still in the future.
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Ilgen J, Nowag J, Kaltschnee L, Schmidts V, Thiele CM. Gradient selected pure shift EASY-ROESY techniques facilitate the quantitative measurement of 1H, 1H-distance restraints in congested spectral regions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 324:106900. [PMID: 33503522 DOI: 10.1016/j.jmr.2020.106900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
For elucidating molecular structure and dynamics in solution, NMR experiments such as NOESY, ROESY and EXSY have been used excessively over the past decades, to provide interatomic distance restraints or rates for chemical exchange. The extraction of such information, however, is often prohibited by signal overlap in these spectra. To reduce this problem, pure shift methods for improving the spectral resolution have become popular. We report on pure shift EASY-ROESY experiments and their application to extract cross-relaxation rates, proton-proton distances and exchange rates. Homonuclear decoupling (pure shift) is applied in the indirect dimension using the PSYCHE or the perfectBASH technique, to enhance the spectral resolution of severely overcrowded spectral regions. The spectral quality is further improved by using a gradient selected F1-PSYCHE-EASY-ROESY, which produces significantly less t1-noise than the experiment used previously, as also demonstrated by employing the recently introduced SAN (signal-artefact-noise) plots. Applications include the quantification of distance restraints in a peptide organocatalyst and the extraction of a number of distance restraints in cyclosporine A, which were previously not available for analysis, because they were either located in overcrowded spectral regions or hidden under t1-noise. Distances extracted and exchange rates obtained are accurate. Also, the 2D gradient-selected F1-perfectBASH-EASY-ROESY with the additional gradient selection proposed herein, which is superior in terms of sensitivity, can be used to accurately quantify cross-relaxation.
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Affiliation(s)
- Julian Ilgen
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany
| | - Jens Nowag
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany
| | - Lukas Kaltschnee
- Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration (BIN), Von-Siebold-Str. 3a, 37075 Göttingen, Germany
| | - Volker Schmidts
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany
| | - Christina M Thiele
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany.
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Dal Poggetto G, Soares JV, Tormena CF. Selective Nuclear Magnetic Resonance Experiments for Sign-Sensitive Determination of Heteronuclear Couplings: Expanding the Analysis of Crude Reaction Mixtures. Anal Chem 2020; 92:14047-14053. [PMID: 32924438 PMCID: PMC7660590 DOI: 10.1021/acs.analchem.0c02976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
State-of-the-art nuclear magnetic resonance (NMR) selective experiments are capable of directly analyzing crude reaction mixtures. A new experiment named HD-HAPPY-FESTA yields ultrahigh-resolution total correlation subspectra, which are suitable for sign-sensitive determination of heteronuclear couplings, as demonstrated here by measuring the sign and magnitude for proton-fluorine couplings (JHF) from major and minor isomer products of a two-step reaction without any purification. Proton-fluorine couplings ranging from 51.5 to -2.6 Hz could be measured using HD-HAPPY-FESTA, with the smallest measured magnitude of 0.8 Hz. Experimental JHF values were used to identify the two fluoroketone intermediates and the four fluoroalcohol products. Results were rationalized and compared with the density functional theory (DFT) calculations. Experimental data were further compared with the couplings reported in the literature, where pure samples were analyzed.
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Affiliation(s)
- Guilherme Dal Poggetto
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
| | - João Vitor Soares
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
| | - Cláudio F Tormena
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
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Lin Y, Zeng Q, Lin L, Chen Z, Barker PB. High-resolution methods for the measurement of scalar coupling constants. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 109:135-159. [PMID: 30527134 DOI: 10.1016/j.pnmrs.2018.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 08/14/2018] [Accepted: 08/14/2018] [Indexed: 06/09/2023]
Abstract
Scalar couplings provide important information regarding molecular structure and dynamics. The measurement of scalar coupling constants constitutes a topic of interest and significance in NMR spectroscopy. However, the measurement of J values is often not straightforward because of complex signal splitting patterns and signal overlap. Many methods have been proposed for the measurement of scalar coupling constants, both for homonuclear and heteronuclear cases. Different approaches to the measurement of scalar coupling constants are reviewed here with several applications presented. The accurate measurement of scalar coupling constants can greatly facilitate molecular structure elucidation and the study of molecule dynamics.
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Affiliation(s)
- Yanqin Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China.
| | - Qing Zeng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Liangjie Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Zhong Chen
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China
| | - Peter B Barker
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; F. M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205, USA
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Dumez JN. Spatial encoding and spatial selection methods in high-resolution NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 109:101-134. [PMID: 30527133 DOI: 10.1016/j.pnmrs.2018.08.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 08/01/2018] [Accepted: 08/01/2018] [Indexed: 06/09/2023]
Abstract
A family of high-resolution NMR methods share the common concept of acquiring in parallel different sub-experiments in different spatial regions of the NMR tube. These spatial encoding and spatial selection methods were for the most part introduced independently from each other and serve different purposes, but they share common ingredients, often derived from magnetic resonance imaging, and they all benefit from a greatly improved time-efficiency. This review article provides a description of several spatial encoding and spatial selection methods, including single-scan multidimensional experiments (ultrafast 2D NMR, DOSY, Z spectroscopy, inversion recovery and Laplace NMR), pure shift and selective refocusing experiments (including Zangger-Sterk decoupling, G-SERF and PSYCHE), a Z filter, and fast-pulsing slice-selective experiments. Some key elements for spatial parallelisation are introduced and when possible a common framework is used for the analysis of each method. Sensitivity considerations are discussed, and a selection of applications is analysed to illustrate which questions can be answered thanks to spatial encoding and spatial selection methods, and discuss the perspectives for future developments and applications.
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Affiliation(s)
- Jean-Nicolas Dumez
- Institut de Chimie des Substances Naturelles, CNRS UPR2301, Univ. Paris Sud, Université Paris-Saclay, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
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Timári I, Kövér KE. Broadband homonuclear decoupled HSQMBC methods. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:910-917. [PMID: 29240977 DOI: 10.1002/mrc.4700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/03/2017] [Accepted: 12/05/2017] [Indexed: 06/07/2023]
Abstract
Long-range heteronuclear coupling constants convey invaluable information for stereochemical and conformational analysis of molecules from synthetic and natural origin. Here, we report a real-time Zangger-Sterk CPMG-HSQMBC method for the precise and direct measurement of multiple-bond heteronuclear couplings. It is demonstrated that the real-time acquisition strategy combined with multiple slice selective excitation can provide substantial improvement in sensitivity (or reduction of experimental time) as compared to other variants of broadband homonuclear decoupled HSQMBC methods published previously. Scope and limitations of the different strategies applied for decoupling are reviewed. Moreover, practical guidelines for the choice of the most appropriate method are also presented. Applications are given on a metal complex incorporating P-heterocycles and two diglycosyl-selenides for the extraction of n J(1 H, 31 P) and n J(1 H, 77 Se), respectively.
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Affiliation(s)
- István Timári
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, H-4032, Debrecen, Hungary
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, 43210, Columbus, OH, USA
| | - Katalin E Kövér
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, H-4032, Debrecen, Hungary
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9
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Bigler P, Furrer J. Measurement of long-range heteronuclear coupling constants using the peak intensity in classical 1D HMBC spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:329-337. [PMID: 29336081 DOI: 10.1002/mrc.4713] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/04/2018] [Accepted: 01/05/2018] [Indexed: 06/07/2023]
Abstract
In this contribution, we show that the magnitude of heteronuclear long-range coupling constants can be directly extracted from the classical 1D HMBC spectra, as all multiplet lines of a cross-peak always and exclusively vanish for the condition Δ = k/n JCH . To the best of our knowledge, this feature of the classical HMBC has not yet been noticed and exploited. This condition holds true, irrespective of the magnitude and numbers of additional active and passive homonuclear n JHH' couplings. Alternatively, the n JCH value may also be evaluated by fitting the peak's intensity in the individual spectra to its simple sin(πn JCH Δ)exp(-Δ/T2eff ) dependence. Compared to the previously proposed J-HMBC sequences that also use the variation of the cross-peak's intensity for extracting the coupling constants, the classical HMBC pulse sequence is significantly more sensitive.
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Affiliation(s)
- Peter Bigler
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, Berne, CH-3012, Switzerland
| | - Julien Furrer
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, Berne, CH-3012, Switzerland
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10
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Ilgen J, Kaltschnee L, Thiele CM. A pure shift experiment with increased sensitivity and superior performance for strongly coupled systems. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 286:18-29. [PMID: 29172170 DOI: 10.1016/j.jmr.2017.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/03/2017] [Accepted: 11/05/2017] [Indexed: 06/07/2023]
Abstract
Motivated by the persisting need for enhanced resolution in solution state NMR spectra, pure shift techniques such as Zangger-Sterk decoupling have recently attracted widespread interest. These techniques for homonuclear decoupling offer enhanced resolution in one- and multidimensional proton detected experiments by simplifying multiplet structures. In this work, a modification to the popular Zangger-Sterk technique PEPSIE (Perfect Echo Pure Shift Improved Experiment) is presented, which decouples pairs of spins even if they share the same volume element. This in turn can drastically improve the sensitivity, as compared to classical Zangger-Sterk decoupling, as larger volume elements can be used to collect the detected signal. Most interestingly, even in the presence of moderate strong coupling, the PEPSIE experiment produces clean and widely artifact free spectra. In order to better understand this - to us initially - surprising behaviour we performed analyses using numerical simulations and derived an (approximate) analytical solution from density matrix formalism. We show that this experiment is particularly suitable to study samples with strong signal clustering, a situation which can render classic Zangger-Sterk decoupling inefficient.
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Affiliation(s)
- Julian Ilgen
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany
| | - Lukas Kaltschnee
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany
| | - Christina M Thiele
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, D-64287 Darmstadt, Germany.
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11
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Castañar L. Pure shift 1 H NMR: what is next? MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:47-53. [PMID: 27761957 DOI: 10.1002/mrc.4545] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/14/2016] [Accepted: 10/17/2016] [Indexed: 06/06/2023]
Abstract
Currently, pure shift nuclear magnetic resonance (NMR) is an area of high interest. The aim of this contribution is to describe briefly how this technique has evolved, where it is now and what could be the next challenges in the amazing adventure of the development and application of pure shift NMR experiments. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Laura Castañar
- School of Chemistry, University of Manchester, Manchester, UK
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Schmidts V. Perspectives in the application of residual dipolar couplings in the structure elucidation of weakly aligned small molecules. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:54-60. [PMID: 27743456 DOI: 10.1002/mrc.4543] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/10/2016] [Accepted: 10/13/2016] [Indexed: 05/28/2023]
Abstract
This perspective article aims to review the general methodology in the application of residual dipolar couplings (RDCs) in the structure elucidation of small molecules and give the author's view on challenges for future applications. Recent improvements in the availability of alignment media, new pulse sequences for the measurement of couplings and improvements in the analysis software have garnered widespread interest in the technique. However, further generalization is needed in order to make RDC analysis into a truly "routine" method. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Volker Schmidts
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Darmstadt, Germany
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Koskela H, Kilpeläinen I, Heikkinen S. ME-CAGEBIRD r,X-CPMG-HSQMBC. A phase sensitive, multiplicity edited long range HSQC with absorptive line shapes. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 272:114-122. [PMID: 27689530 DOI: 10.1016/j.jmr.2016.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/15/2016] [Accepted: 09/15/2016] [Indexed: 06/06/2023]
Abstract
ME-CAGEBIRDr,X-CPMG-HSMBC pulse sequence is a phase sensitive, carbon multiplicity edited 2D-experiment for detecting heteronuclear correlations originating from long-range 1H, 13C-couplings, nJCH. The presented method allows measurement of nJCH-values as well as is capable of separating different carbon types in subspectra (13C/13CH2 and 13CH/13CH3) with minimal amount of cross talk i.e. cross peaks from wrong carbon multiplicity. Pure lineshapes and clean subspectra are achieved by utilizing CPMG in polarization transfer period, CRISIS-approach in multiplicity editing period and zero-quantum filtration. The obtained spectral properties together with simple setup of the experiment make ME-CAGEBIRDr,X-CPMG-HSMBC a useful addition into synthetic organic chemistry oriented NMR-tool collection.
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Affiliation(s)
- Harri Koskela
- VERIFIN, Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Ilkka Kilpeläinen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Sami Heikkinen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
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Glanzer S, Kunert O, Zangger K. Determination of unresolved heteronuclear scalar coupling constants by J(up)-HSQMBC. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 268:88-94. [PMID: 27183090 DOI: 10.1016/j.jmr.2016.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 02/25/2016] [Accepted: 05/05/2016] [Indexed: 06/05/2023]
Abstract
Long-range heteronuclear scalar coupling constants provide important structural information, which is necessary for obtaining stereospecific assignment or dihedral angle information. The measurement of small proton-carbon splittings is particularly difficult due to the low natural abundance of carbon-13 and the presence of homonuclear couplings of similar size. Here we present a real-time J-upscaled HSQMBC, which allows the measurement of heteronuclear coupling constants even if they are hidden in the signal linewidth of a regular spectrum.
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Affiliation(s)
- Simon Glanzer
- Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, Austria
| | - Olaf Kunert
- Institute of Pharmaceutical Sciences/Pharmaceutical Chemistry, University of Graz, Austria
| | - Klaus Zangger
- Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, Austria.
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15
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Timári I, Szilágyi L, Kövér KE. PSYCHE CPMG–HSQMBC: An NMR Spectroscopic Method for Precise and Simple Measurement of Long‐Range Heteronuclear Coupling Constants. Chemistry 2015; 21:13939-42. [DOI: 10.1002/chem.201502641] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/08/2022]
Affiliation(s)
- István Timári
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, H‐4032 Debrecen (Hungary)
| | - László Szilágyi
- Department of Organic Chemistry, University of Debrecen, Egyetem tér 1, H‐4032 Debrecen (Hungary)
| | - Katalin E. Kövér
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, H‐4032 Debrecen (Hungary)
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16
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Castañar L, Parella T. Broadband 1H homodecoupled NMR experiments: recent developments, methods and applications. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:399-426. [PMID: 25899911 DOI: 10.1002/mrc.4238] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/23/2015] [Accepted: 02/25/2015] [Indexed: 06/04/2023]
Abstract
In recent years, a great interest in the development of new broadband 1H homonuclear decoupled techniques providing simplified JHH multiplet patterns has emerged again in the field of small molecule NMR. The resulting highly resolved 1H NMR spectra display resonances as collapsed singlets, therefore minimizing signal overlap and expediting spectral analysis. This review aims at presenting the most recent advances in pure shift NMR spectroscopy, with a particular emphasis to the Zangger-Sterk experiment. A detailed discussion about the most relevant practical aspects in terms of pulse sequence design, selectivity, sensitivity, spectral resolution and performance is provided. Finally, the implementation of the different reported strategies into traditional 1D and 2D NMR experiments is described while several practical applications are also reviewed.
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Affiliation(s)
- Laura Castañar
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Barcelona, Catalonia, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear and Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Barcelona, Catalonia, Spain
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