1
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Dorst KM, Widmalm G. Conformational Preferences at the Glycosidic Linkage of Saccharides in Solution as Deduced from NMR Experiments and MD Simulations: Comparison to Crystal Structures. Chemistry 2024; 30:e202304047. [PMID: 38180821 DOI: 10.1002/chem.202304047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/30/2023] [Accepted: 01/05/2024] [Indexed: 01/07/2024]
Abstract
Glycans are central to information content and regulation in biological systems. These carbohydrate molecules are active either as oligo- or polysaccharides, often in the form of glycoconjugates. The monosaccharide entities are joined by glycosidic linkages and stereochemical arrangements are of utmost importance in determining conformation and flexibility of saccharides. The conformational preferences and population distributions at the glycosidic torsion angles φ and ψ have been investigated for O-methyl glycosides of three disaccharides where the substitution takes place at a secondary alcohol, viz., in α-l-Fucp-(1→3)-β-d-Glcp-OMe, α-l-Fucp-(1→3)-α-d-Galp-OMe and α-d-Glcp-(1→4)-α-d-Galp-OMe, corresponding to disaccharide structural elements present in bacterial polysaccharides. Stereochemical differences at or adjacent to the glycosidic linkage were explored by solution state NMR spectroscopy using one-dimensional 1 H,1 H-NOESY NMR experiments to obtain transglycosidic proton-proton distances and one- and two-dimensional heteronuclear NMR experiments to obtain 3 JCH transglycosidic coupling constants related to torsion angles φ and ψ. Computed effective proton-proton distances from molecular dynamics (MD) simulations showed excellent agreement to experimentally derived distances for the α-(1→3)-linked disaccharides and revealed that for the bimodal distribution at the ψ torsion angle for the α-(1→4)-linked disaccharide experiment and simulation were at variance with each other, calling for further force field developments. The MD simulations disclosed a highly intricate inter-residue hydrogen bonding pattern for the α-(1→4)-linked disaccharide, including a nonconventional hydrogen bond between H5' in the glucosyl residue and O3 in the galactosyl residue, supported by a large downfield 1 H NMR chemical shift displacement compared to α-d-Glcp-OMe. Comparison of population distributions of the glycosidic torsion angles φ and ψ in the disaccharide entities to those of corresponding crystal structures highlighted the potential importance of solvation on the preferred conformation.
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Affiliation(s)
- Kevin M Dorst
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91, Stockholm, Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91, Stockholm, Sweden
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2
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Mycroft C, Dal Poggetto G, Barbosa TM, Tormena C, Nilsson M, Morris GA, Castañar L. Rapid Measurement of Heteronuclear Coupling Constants in Complex NMR Spectra. J Am Chem Soc 2023; 145:19824-19831. [PMID: 37650656 PMCID: PMC10510310 DOI: 10.1021/jacs.3c05515] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Indexed: 09/01/2023]
Abstract
The NMR analysis of fluorine-containing molecules, increasingly widespread due to their importance in pharmaceuticals and biochemistry, poses significant challenges. Severe peak overlap in the proton spectrum often hinders the extraction of critical structural information in the form of heteronuclear scalar coupling constants, which are crucial for determining pharmaceutical properties and biological activity. Here, a new method, IPAP-FESTA, is reported that drastically simplifies measurements of the signs and magnitudes of proton-fluorine couplings. Its usefulness is demonstrated for the structural study of the steroidal drug fluticasone propionate extracted from a commercial formulation and for assessing solvent effects on the conformational equilibrium in a physically inseparable fluorohydrin mixture.
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Affiliation(s)
- Coral Mycroft
- Department
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
- Chemistry
Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, United
Kingdom
| | - Guilherme Dal Poggetto
- Chemistry
Institute, University of Campinas −
UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP, Brazil
- Analytical
Research & Development, Merck &
Co., Inc., 126 Lincoln Avenue, Rahway, New Jersey 07065, United States
| | - Thaís M. Barbosa
- Chemistry
Institute, University of Campinas −
UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP, Brazil
- Nanalysis
Corp., 1-4600 5 Street NE, Calgary, Alberta, Canada T2E 7C3
| | - Cláudio
F. Tormena
- Chemistry
Institute, University of Campinas −
UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP, Brazil
| | - Mathias Nilsson
- Department
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Gareth A. Morris
- Department
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Laura Castañar
- Department
of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
- Department
of Organic Chemistry, Faculty of Chemical Science, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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3
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Navarro-Vázquez A, Pennestri M. Karplus relationships of the 2 J HNα and 3 J ΗΝβ couplings in organic azides. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:187-194. [PMID: 32929782 DOI: 10.1002/mrc.5101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/02/2020] [Accepted: 09/12/2020] [Indexed: 06/11/2023]
Abstract
Density functional theory (DFT) and second-order polarization propagator approximation (SOPPA) computations in model organic azides revealed a Karplus-like dependence not only of the vicinal 3 JH-C-Nα-Nβ coupling but also of the geminal 2 JH-C-Nα one, with the H-C-Nα Nβ dihedral angle. Karplus equations were derived from the DFT computations on the isopropylazide model system. In light of these stablished relationships, natural abundance 1 H-15 N couplings obtained for the azide group of the zidovudine antiviral helped to probe its conformation around the C-Nα bond as being of the synclinal type.
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Affiliation(s)
- Armando Navarro-Vázquez
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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4
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Chemical Analysis of Fluorobenzenes via Multinuclear Detection in the Strong Heteronuclear J-Coupling Regime. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10113836] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chemical analysis via nuclear magnetic resonance (NMR) spectroscopy using permanent magnets, rather than superconducting magnets, is a rapidly developing field. Performing the NMR measurement in the strong heteronuclear J-coupling regime has shown considerable promise for the chemical analysis of small molecules. Typically, the condition for the strong heteronuclear J-coupling regime is satisfied at µT magnetic field strengths and enables high resolution J-coupled spectra (JCS) to be acquired. However, the JCS response to systematic chemical structural changes has largely not been investigated. In this report, we investigate the JCS of C6H6−xFx (x = 0, 1, 2, …, 6) fluorobenzene compounds via simultaneous excitation and detection of 19F and 1H at 51.5 µT. The results demonstrate that JCS are quantitative, and the common NMR observables, including Larmor frequency, heteronuclear and homonuclear J-couplings, relative signs of the J-coupling, chemical shift, and relaxation, are all measurable and are differentiable between molecules at low magnetic fields. The results, corroborated by ab initio calculations, provide new insights into the impact of chemical structure and their corresponding spin systems on JCS. In several instances, the JCS provided more chemical information than traditional high field NMR, demonstrating that JCS can be used for robust chemical analysis.
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5
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Saurí J, Nolis P, Parella T. How to measure long-range proton-carbon coupling constants from 1 H-selective HSQMBC experiments. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:363-375. [PMID: 32239575 DOI: 10.1002/mrc.4928] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/27/2019] [Accepted: 07/18/2019] [Indexed: 06/11/2023]
Abstract
Heteronuclear long-range scalar coupling constants (n JCH ) are a valuable tool for solving problems in organic chemistry and are especially suited for stereochemical and configurational analyses of small molecules and natural products. This tutorial will focus on the step-by-step implementation of several 2D 1 H frequency selective HSQMBC experiments for the easy and accurate measurement of either the magnitude or both the magnitude and the sign of long-range n JCH couplings. The performance of these experiments will be showcased with several scenarios in a range of different experimental conditions.
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Affiliation(s)
- Josep Saurí
- Structure Elucidation Group, Analytical Research and Development, Merck & Co., Inc., Boston, MA
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, Barcelona, Spain
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6
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Motiram-Corral K, Nolis P, Saurí J, Parella T. LR-HSQMBC versus LR-selHSQMBC: Enhancing the Observation of Tiny Long-Range Heteronuclear NMR Correlations. JOURNAL OF NATURAL PRODUCTS 2020; 83:1275-1282. [PMID: 32155071 DOI: 10.1021/acs.jnatprod.0c00058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The detection of ultra-long-range (4JCH and higher) heteronuclear connectivities can complement the conventional use of HMBC/HSQMBC data in structure elucidation NMR studies of proton-deficient natural products, where two-bond and three-bond correlations are usually observed. The performance of the selHSQMBC experiment with respect to its broadband HSQMBC counterpart is evaluated. Despite its frequency-selectivity nature, selHSQMBC efficiently prevents any unwanted signal phase and intensity modulations due to passive proton-proton coupling constants typically involved in HSQMBC. As a result, selHSQMBC offers a significant sensitivity enhancement and provides pure in-phase multiplets, improving the detection levels for short- and long-range cross-peaks corresponding to small heteronuclear coupling values. This is particularly relevant for experiments optimized to small nJCH values (2-3 Hz), referred to as LR-selHSQMBC, where key cross-peaks that are not visible in the equivalent broadband LR-HSQMBC spectrum can become observable in optimum conditions.
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Affiliation(s)
- Kumar Motiram-Corral
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
| | - Josep Saurí
- Structure Elucidation Group, Analytical Research & Development, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
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7
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Couto UR, Navarro-Vázquez A, Tormena CF. Unexpected behavior of the 3 J CH coupling constant in unsaturated compounds. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:939-945. [PMID: 31066094 DOI: 10.1002/mrc.4885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 06/09/2023]
Abstract
The experimental and theoretical behavior of the (OC)CCH 3 JCH coupling constant is investigated for a series of α,β-unsaturated compounds (1 to 8), and for some of them, the well-known relationship (3 JCHcis < 3 JCHtrans ) was observed. However, for some compounds, close values for 3 JCHcis and 3 JCHtrans couplings were observed, and for aldehydes group containing compounds (7 and 8E), an inversion order is observed (3 JCHcis > 3 JCHtrans ). In all cases where the 3 JCHcis < 3 JCHtrans relationship it is not followed, a polar group or electronegative atom oriented in opposite direction (s-trans) to the HCC hydrogen is present, suggesting that conformational preference of such polar group or atoms are important factor on the behavior of 3 JCH couplings. Taking all of these in consideration, a new Karplus-type equation was proposed for 3 JCH couplings in α,β-unsaturated compounds, which can be used for configurational and conformational assignment on trisubstituted double bond derivatives.
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Affiliation(s)
| | - Armando Navarro-Vázquez
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Cidade Universitária, Recife, Brazil
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8
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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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9
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Bigler P, Furrer J. D-HMBC versus LR-HSQMBC: Which experiment provides theoretically and experimentally the best results? MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 57:129-143. [PMID: 30499122 DOI: 10.1002/mrc.4810] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/21/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
The long-range heteronuclear single quantum multiple bond correlation (LR-HSQMBC) experiment is the experiment of choice for visualizing heteronuclear long-range coupling interactions n JCH across 4-6-bonds and is experimentally superior to the decoupled heteronuclear multiple-bond correlation (D-HMBC) experiment. Yet, the exact reasons have not been fully understood and established. On the basis of our recent investigation of the nonrefocused variants LR-HSQC and HMBC, we have extended a JHH' -dedicated investigation to the D-HMBC and LR-HSQMBC experiments. Unlike the nonrefocused variants, the influence of homonuclear couplings JHH' on the intensity of long-range n JCH cross-peaks is not easily predictable and may be summarized as follows: (a) irrespective of the magnitude and number of JHH' interactions long-range n JCH cross-peaks are more intense in D-HMBC spectra as long as the evolution delay Δ is not too large, because in contrast to LR-HSQMBC no JHH' -caused intensity zeroes will occur. (b) If JHH' is small and Δ large, the intensity of cross peaks in D-HMBC spectra may be weakened or may even vanish at Δ = (0.25+0.5k)/JHH ', whereas for the LR-HSQMBC this unwanted effect occurs at Δ = k + 0.5/JHH' . Consequently, when Δ is adjusted to visualize weak n JCH long-range correlations, our findings corroborate that there are potentially more cross-peaks expected to show up in a LR-HSQMBC spectrum compared with a D-HMBC spectrum. This has been indeed noticed experimentally, even though the intensity of a many long-range n JCH cross-peaks may still be higher in the spectra of the D-HMBC experiment correspondingly adjusted for detecting weak n JCH correlations.
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Affiliation(s)
- Peter Bigler
- Departement für Chemie und Biochemie, Universität Bern, Bern, Switzerland
| | - Julien Furrer
- Departement für Chemie und Biochemie, Universität Bern, Bern, Switzerland
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10
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Bertin MJ, Saurí J, Liu Y, Via CW, Roduit AF, Williamson RT. Trichophycins B-F, Chlorovinylidene-Containing Polyketides Isolated from a Cyanobacterial Bloom. J Org Chem 2018; 83:13256-13266. [PMID: 30280904 DOI: 10.1021/acs.joc.8b02070] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NMR-guided isolation (based on 1D 1H and 13C NMR resonances consistent with a chlorovinylidene moiety) resulted in the characterization of five new highly functionalized polyketides, trichophycins B-F (1-5), and one nonchlorinated metabolite tricholactone (6) from a collection of Trichodesmium bloom material from the Gulf of Mexico. The planar structures of 1-6 were determined using 1D and 2D NMR spectroscopy, mass spectrometry, and complementary spectroscopic procedures. Absolute configuration analysis of 1 and 2 were carried out by 1H NMR analysis of diastereomeric Mosher esters in addition to ECD spectroscopy, J-based configuration analysis, and DFT calculations. The absolute configurations of 3-6 were proposed on the basis of comparative analysis of 13C NMR chemical shifts, relative configurations, and optical rotation values to compounds 1 and 2. Compounds 1-5 represent new additions to the trichophycin family and are hallmarked by a chlorovinylidene moiety. These new trichophycins and tricholactone (1-6) feature intriguing variations with respect to putative biosynthetic starting units, halogenation, and terminations, and trichophycin E (4) features a rare alkynyl bromide functionality. The phenyl-containing trichophycins showed low cytotoxicity to neuro-2A cells, while the alkyne-containing trichophycins showed no toxicity.
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Affiliation(s)
- Matthew J Bertin
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy , University of Rhode Island , 7 Greenhouse Road , Kingston , Rhode Island 02881 , United States
| | - Josep Saurí
- Structure Elucidation Group, Process and Analytical Research and Development , Merck and Co. Inc , 33 Avenue Louis Pasteur , Boston , Massachusetts 02115 , United States
| | - Yizhou Liu
- Structure Elucidation Group, Process and Analytical Research and Development , Merck and Co. Inc , 126 East Lincoln Avenue , Rahway , New Jersey 07065 , United States
| | - Christopher W Via
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy , University of Rhode Island , 7 Greenhouse Road , Kingston , Rhode Island 02881 , United States
| | - Alexandre F Roduit
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy , University of Rhode Island , 7 Greenhouse Road , Kingston , Rhode Island 02881 , United States
| | - R Thomas Williamson
- Structure Elucidation Group, Process and Analytical Research and Development , Merck and Co. Inc , 126 East Lincoln Avenue , Rahway , New Jersey 07065 , United States
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11
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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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12
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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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13
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Souza AA, Gil RR, Parella T. Highly resolved HSQC experiments for the fast and accurate measurement of homonuclear and heteronuclear coupling constants. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 282:54-61. [PMID: 28759743 DOI: 10.1016/j.jmr.2017.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/10/2017] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
A number of J-upscaled NMR experiments are currently available to measure coupling constants along the indirect F1 dimension of a 2D spectrum. A major drawback is the limited F1 digital resolution that requires long acquisition times in order to achieve reasonably accurate measures. Here is shown how high levels of F1 digital resolution in a multiple-purpose HSQC experiment can be easily achieved by implementing a general J/δ-scaling strategy. In particular, a set of new J-resolved HSQC experiments is presented for a faster and much more accurate J determination in small molecules. Several options and practical aspects are discussed and exemplified by measuring the magnitude and/or the sign of several homo- and heteronuclear coupling constants in one shot.
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Affiliation(s)
- Alexandre A Souza
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Catalonia, Spain; Departamento de Química, Universidade Federal do Piauí, 64049-550 Teresina, PI, Brazil
| | - Roberto R Gil
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Barcelona), Catalonia, Spain.
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14
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Dickson CL, Blundell CD, Butts CP, Felton A, Jeffreys A, Takacs Z. Accurate measurement of long range proton–carbon scalar coupling constants. Analyst 2017; 142:621-633. [DOI: 10.1039/c6an02298g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The accuracy and ease-of-use of various experimental NMR methods for measuringnJCHvalues is assessed.
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Affiliation(s)
| | | | | | - Alice Felton
- University of Bristol
- School of Chemistry
- Bristol
- UK
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15
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Pierens GK, Venkatachalam TK, Reutens DC. Investigation of two- and three-bond carbon-hydrogen coupling constants in cinnamic acid based compounds. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:941-946. [PMID: 27356919 DOI: 10.1002/mrc.4469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 06/06/2023]
Abstract
Two- and three-bond coupling constants (2 JHC and 3 JHC ) were determined for a series of 12 substituted cinnamic acids using a selective 2D inphase/antiphase (IPAP)-single quantum multiple bond correlation (HSQMBC) and 1D proton coupled 13 C NMR experiments. The coupling constants from two methods were compared and found to give very similar values. The results showed coupling constant values ranging from 1.7 to 9.7 Hz and 1.0 to 9.6 Hz for the IPAP-HSQMBC and the direct 13 C NMR experiments, respectively. The experimental values of the coupling constants were compared with discrete density functional theory (DFT) calculated values and were found to be in good agreement for the 3 JHC . However, the DFT method under estimated the 2 JHC coupling constants. Knowing the limitations of the measurement and calculation of these multibond coupling constants will add confidence to the assignment of conformation or stereochemical aspects of complex molecules like natural products. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Gregory K Pierens
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
| | | | - David C Reutens
- Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia
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16
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Saurí J, Reibarkh M, Zhang T, Cohen RD, Wang X, Molinski TF, Martin GE, Williamson RT. Band-Selective 2D HSQMBC: A Universal Technique for Detection and Measurement of 35,37Cl Isotope Effects for 13C Nuclei. Org Lett 2016; 18:4786-4789. [DOI: 10.1021/acs.orglett.6b02158] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Josep Saurí
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Mikhail Reibarkh
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Ting Zhang
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Ryan D. Cohen
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Xiao Wang
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Tadeusz F. Molinski
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - Gary E. Martin
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
| | - R. Thomas Williamson
- NMR Structure Elucidation, Process Research and Development and ‡Discovery Chemistry, MRL, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, United States
- Department of Chemistry and Biochemistry and ∥Skaggs School of
Pharmacy and Pharmaceutical
Sciences, University of California, San Diego, 9500 Gilman Drive
MC-0358, La Jolla, California 92093, United States
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17
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Mevers E, Saurí J, Liu Y, Moser A, Ramadhar TR, Varlan M, Williamson RT, Martin GE, Clardy J. Homodimericin A: A Complex Hexacyclic Fungal Metabolite. J Am Chem Soc 2016; 138:12324-7. [PMID: 27608853 PMCID: PMC5533454 DOI: 10.1021/jacs.6b07588] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbes sense and respond to their environment with small molecules, and discovering these molecules and identifying their functions informs chemistry, biology, and medicine. As part of a study of molecular exchanges between termite-associated actinobacteria and pathogenic fungi, we uncovered a remarkable fungal metabolite, homodimericin A, which is strongly upregulated by the bacterial metabolite bafilomycin C1. Homodimericin A is a hexacyclic polyketide with a carbon backbone containing eight contiguous stereogenic carbons in a C20 hexacyclic core. Only half of its carbon atoms have an attached hydrogen, which presented a significant challenge for NMR-based structural analysis. In spite of its microbial production and rich stereochemistry, homodimericin A occurs naturally as a racemic mixture. A plausible nonenzymatic reaction cascade leading from two identical achiral monomers to homodimericin A is presented, and homodimericin A's formation by this path, a six-electron oxidation, could be a response to oxidative stress triggered by bafilomycin C1.
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Affiliation(s)
- Emily Mevers
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School , 240 Longwood Avenue, Boston, Massachusetts 02115, United States
| | - Josep Saurí
- Process Research and Development, NMR Structure Elucidation Group, Merck & Co., Inc. , Mail Stop RY800-C163, 126 East Lincoln Avenue, Rahway, New Jersey 07065 United States
| | - Yizhou Liu
- Process Research and Development, NMR Structure Elucidation Group, Merck & Co., Inc. , Mail Stop RY800-C163, 126 East Lincoln Avenue, Rahway, New Jersey 07065 United States
| | - Arvin Moser
- Advanced Chemistry Development, Inc. (ACD/Laboratories) Toronto Department, 8 King Street East, Suite 107, Toronto, ON M5C 1B5, Canada
| | - Timothy R Ramadhar
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School , 240 Longwood Avenue, Boston, Massachusetts 02115, United States
| | - Maria Varlan
- Advanced Chemistry Development, Inc. (ACD/Laboratories) Toronto Department, 8 King Street East, Suite 107, Toronto, ON M5C 1B5, Canada
| | - R Thomas Williamson
- Process Research and Development, NMR Structure Elucidation Group, Merck & Co., Inc. , Mail Stop RY800-C163, 126 East Lincoln Avenue, Rahway, New Jersey 07065 United States
| | - Gary E Martin
- Process Research and Development, NMR Structure Elucidation Group, Merck & Co., Inc. , Mail Stop RY800-C163, 126 East Lincoln Avenue, Rahway, New Jersey 07065 United States
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School , 240 Longwood Avenue, Boston, Massachusetts 02115, United States
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18
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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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19
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Kutateladze AG, Mukhina OA. Relativistic Force Field: Parametrization of 13C–1H Nuclear Spin–Spin Coupling Constants. J Org Chem 2015; 80:10838-48. [DOI: 10.1021/acs.joc.5b02001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrei G. Kutateladze
- Department of Chemistry and
Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Olga A. Mukhina
- Department of Chemistry and
Biochemistry, University of Denver, Denver, Colorado 80208, United States
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20
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Saurí J, Frédérich M, Tchinda AT, Parella T, Williamson RT, Martin GE. Carbon Multiplicity Editing in Long-Range Heteronuclear Correlation NMR Experiments: A Valuable Tool for the Structure Elucidation of Natural Products. JOURNAL OF NATURAL PRODUCTS 2015; 78:2236-2241. [PMID: 26305494 DOI: 10.1021/acs.jnatprod.5b00447] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A recently developed NMR method to simultaneously obtain both long-range heteronuclear correlations and carbon multiplicity information in a single experiment, ME-selHSQMBC, is demonstrated as a potentially useful technique for chemical shift assignment and structure elucidation of natural products presenting complicated NMR spectra. Carbon multiplicities, even for C/CH2 and odd for CH/CH3 resonances, can be distinguished directly from the relative positive/negative phase of cross-peaks. In addition, connectivity networks can be further extended by incorporating a TOCSY propagation step. Staurosporine (1) and sungucine (2) are utilized as model compounds to demonstrate these techniques.
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Affiliation(s)
- Josep Saurí
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc. , Rahway, New Jersey 07065, United States
| | - Michel Frédérich
- Laboratory of Pharmacognosy, Department of Pharmacy, CIRM, University of Liège , B36, 4000 Liège, Belgium
| | - Alembert T Tchinda
- Center for Studies on Medicinal Plants and Traditional Medicine, Institute of Medical Research and Medicinal Plants Studies (IMPM) , P.O. Box 6163, Yaoundé, Cameroon
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Barcelona, Spain
| | - R Thomas Williamson
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc. , Rahway, New Jersey 07065, United States
| | - Gary E Martin
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc. , Rahway, New Jersey 07065, United States
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21
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Saurí J, Marcó N, Williamson RT, Martin GE, Parella T. Extending long-range heteronuclear NMR connectivities by HSQMBC-COSY and HSQMBC-TOCSY experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 258:25-32. [PMID: 26160012 DOI: 10.1016/j.jmr.2015.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 06/04/2023]
Abstract
The detection of long-range heteronuclear correlations presenting J(CH) coupling values smaller than 1-2Hz is a challenge in the structural analysis of small molecules and natural products. HSQMBC-COSY and HSQMBC-TOCSY pulse schemes are evaluated as complementary NMR methods to standard HMBC/HSQMBC experiments. Incorporation of an additional J(HH) transfer step in the basic HSQMBC pulse scheme can favor the sensitive observation of traditionally missing or very weak correlations and, in addition, facilitates the detection of a significant number of still longer-range connectivities to both protonated and non-protonated carbons under optimum sensitivity conditions. A comparative (1)H-(13)C study is performed using strychnine as a model compound and several examples are also provided including (1)H-(15)N applications.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain; NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Núria Marcó
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
| | - R Thomas Williamson
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Gary E Martin
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain.
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22
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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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23
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Saurí J, Nolis P, Parella T. Simultaneous determination of the magnitude and the sign of multiple heteronuclear coupling constants in 19F or 31P-containing compounds. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:427-432. [PMID: 25891772 DOI: 10.1002/mrc.4239] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/26/2015] [Accepted: 03/02/2015] [Indexed: 06/04/2023]
Abstract
The presence of a highly abundant passive nucleus (Z = 19F or 31P) allows the simultaneous determination of the magnitude and the sign of up to three different heteronuclear coupling constants from each individual cross-peak observed in a 2D 1H-X selHSQMBC spectrum. Whereas J(HZ) and J(XZ) coupling constants are measured from E.COSY multiplet patterns, J(XH) is independently extracted from the complementary IPAP pattern generated along the detected F2 dimension. The incorporation of an extended TOCSY transfer allows the extraction of a complete set of all these heteronuclear coupling constants and their signs for an entire 1H subspin system. 1H-X/1H-Y time-shared versions are also proposed for the simultaneous measurement of five different couplings (J(XH), J(YH), J(XZ), J(YZ), and J(ZH)) for multiple signals in a single NMR experiment.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, E-08193, Barcelona, Catalonia, Spain
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear, Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, E-08193, Barcelona, Catalonia, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, E-08193, Barcelona, Catalonia, Spain
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24
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Saurí J, Sistaré E, Thomas Williamson R, Martin GE, Parella T. Implementing multiplicity editing in selective HSQMBC experiments. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 252:170-175. [PMID: 25702573 DOI: 10.1016/j.jmr.2015.01.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 01/07/2015] [Accepted: 01/11/2015] [Indexed: 06/04/2023]
Abstract
Even C/CH(2) and odd CH/CH(3) carbon-multiplicity information can be directly distinguished from the relative positive/negative phase of cross-peaks in a novel ME (Multiplicity-Edited)-selHSQMBC experiment. The method can be extended by a TOCSY propagation step, and it is fully compatible for the simultaneous and precise determination of long-range heteronuclear coupling constants. Broadband homonuclear decoupling techniques can also be incorporated to enhance sensitivity and signal resolution by effective collapse of J(HH) multiplets.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, Facultat de Ciències, E-08193 Bellaterra (Barcelona), Catalonia, Spain; NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Eduard Sistaré
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, Facultat de Ciències, E-08193 Bellaterra (Barcelona), Catalonia, Spain
| | - R Thomas Williamson
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Gary E Martin
- NMR Structure Elucidation, Process and Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, Facultat de Ciències, E-08193 Bellaterra (Barcelona), Catalonia, Spain.
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25
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Timári I, Illyés TZ, Adams RW, Nilsson M, Szilágyi L, Morris GA, Kövér KE. Precise measurement of long-range heteronuclear coupling constants by a novel broadband proton-proton-decoupled CPMG-HSQMBC method. Chemistry 2015; 21:3472-9. [PMID: 25573660 PMCID: PMC4338765 DOI: 10.1002/chem.201405535] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Indexed: 11/17/2022]
Abstract
A broadband proton–proton-decoupled CPMG-HSQMBC method for the precise and direct measurement of long-range heteronuclear coupling constants is presented. The Zangger–Sterk-based homodecoupling scheme reported herein efficiently removes unwanted proton–proton splittings from the heteronuclear multiplets, so that the desired heteronuclear couplings can be determined simply by measuring frequency differences between singlet maxima in the resulting spectra. The proposed pseudo-1D/2D pulse sequences were tested on nucleotides, a metal complex incorporating P heterocycles, and diglycosyl (di)selenides, as well as on other carbohydrate derivatives, for the extraction of nJ(1H,31P), nJ(1H,77Se), and nJ(1H,13C) values, respectively.
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Affiliation(s)
- István Timári
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, 4032 Debrecen (Hungary)
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26
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Castañar L, Saurí J, Williamson RT, Virgili A, Parella T. Pure In-Phase Heteronuclear Correlation NMR Experiments. Angew Chem Int Ed Engl 2014; 53:8379-82. [DOI: 10.1002/anie.201404136] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Indexed: 11/09/2022]
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27
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Castañar L, Saurí J, Williamson RT, Virgili A, Parella T. Pure In-Phase Heteronuclear Correlation NMR Experiments. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Baishya B, Khetrapal CL. "Perfect echo" INEPT: more efficient heteronuclear polarization transfer by refocusing homonuclear J-coupling interaction. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 242:143-154. [PMID: 24650727 DOI: 10.1016/j.jmr.2014.02.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 06/03/2023]
Abstract
A "perfect echo" based INEPT experiment that demonstrates more efficient heteronuclear polarization transfer over conventional INEPT has been developed. This scheme refocuses the effect of homonuclear (1)H-(1)H J-evolution and simultaneously allows heteronuclear (13)C-(1)H J-evolution to continue during INEPT. This improves one bond heteronuclear polarization transfer efficiency at longer INEPT transfer delays and also enhances the sensitivity of long range INEPT. The refocusing of homonuclear (1)H-(1)H J-coupling could be achieved by doubling the INEPT transfer period leading to a doubling of T2 losses. Therefore, the sensitivity gain is observed when loss of magnetization due to homonuclear (1)H-(1)H J-modulation is more severe than that of T2 decay. However, in general, INEPT transfer period is rather short compared to the longer T2 observed in small molecules. The long range PE-INEPT transfer to carbonyl carbon in beta-butyrolactone, showed much faster build up of C-13 signal than conventional long range INEPT as the long range heteronuclear J-coupling is comparable in magnitude to homonuclear (1)H-(1)H J-coupling in this case. For one bond heteronuclear polarization transfer at shorter delay, PE-INEPT and conventional INEPT displays equal transfer efficiency. Efficient polarization transfer is observed for small molecules dissolved in isotropic as well as weakly aligned media. Further, simulation results obtained using the full propagator and product operator analysis agree well with the experimental observations.
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Affiliation(s)
- Bikash Baishya
- Center of Biomedical Research (Formerly Centre of Biomedical Magnetic Resonance), SGPGIMS Campus, Raebareli Road, Lucknow 226014, India.
| | - C L Khetrapal
- Center of Biomedical Research (Formerly Centre of Biomedical Magnetic Resonance), SGPGIMS Campus, Raebareli Road, Lucknow 226014, India
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29
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Planellas M, Guo W, Alonso F, Yus M, Shafir A, Pleixats R, Parella T. Hydrosilylation of Internal Alkynes Catalyzed by Tris- Imidazolium Salt-Stabilized Palladium Nanoparticles. Adv Synth Catal 2014. [DOI: 10.1002/adsc.201300641] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Saurí J, Nolis P, Parella T. Efficient and fast sign-sensitive determination of heteronuclear coupling constants. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 236:66-69. [PMID: 24056323 DOI: 10.1016/j.jmr.2013.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 08/16/2013] [Accepted: 08/23/2013] [Indexed: 06/02/2023]
Abstract
Two complementary 1D NMR approaches for the fast and easy determination of the magnitude and the sign of heteronuclear J(XH) coupling constants are proposed: The Up&Down technique relies on the direct analysis of anti-phase multiplets whereas the Left&Right technique is based on the relative displacement between separate IPAP components.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
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31
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Saurí J, Parella T. On the interference of J(HH) modulation in HSQMBC-IPAP and HMBC-IPAP experiments. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:509-516. [PMID: 23780917 DOI: 10.1002/mrc.3977] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/22/2013] [Accepted: 05/19/2013] [Indexed: 06/02/2023]
Abstract
The effects of phase modulation due to homonuclear proton-proton coupling constants in HSQMBC-IPAP and HMBC-IPAP experiments are experimentally evaluated. We show that accurate values of small proton-carbon coupling constants, (n)J(CH), can be extracted even for phase-distorted cross-peaks obtained from a selHSQMBC experiment applied simultaneously on two mutually J-coupled protons. On the other hand, an assessment of the reliability of (n)J(CH) measurement from distorted cross-peaks obtained in broadband IPAP versions of equivalent HMBC and HSQMBC experiments is also presented. Finally, we show that HMBC-COSY experiments could be an excellent complement to HMBC for the measurement of small (n)J(CH) values.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Catalonia, Spain
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32
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Parella T, Espinosa JF. Long-range proton-carbon coupling constants: NMR methods and applications. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 73:17-55. [PMID: 23962883 DOI: 10.1016/j.pnmrs.2013.07.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 07/03/2013] [Accepted: 07/03/2013] [Indexed: 06/02/2023]
Abstract
A general review of novel NMR methods to measure heteronuclear long-range proton-carbon coupling constants ((n)JCH; n>1) in small molecules is made. NMR experiments are classified in terms of NMR pulse scheme and cross-peak nature. A discussion about simplicity, general applicability and accuracy for each particular NMR experiment is presented and exemplified. Important aspects such as the sign determination and measurement of very small coupling values involving protonated and non-protonated carbons as well as the complementarity between different experiments are also discussed. Finally, a compilation of applications in structural and conformational analysis of different types of molecules since 2000 is surveyed.
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Affiliation(s)
- Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
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33
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Saurí J, Parella T. Simultaneous measurement of J(HH) and two different (n)J(CH) coupling constants from a single multiply edited 2D cross-peak. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:397-402. [PMID: 23649408 DOI: 10.1002/mrc.3960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 06/02/2023]
Abstract
Three different J-editing methods (IPAP, E.COSY and J-resolved) are implemented in a single NMR experiment to provide spin-state-edited 2D cross-peaks from which a simultaneous measurement of different homonuclear and heteronuclear coupling constants can be performed. A new J-selHSQMBC-IPAP experiment is proposed for the independent measurement of two different (n)J(CH) coupling constants along the F2 and F1 dimensions of the same 2D cross-peak. In addition, the E.COSY pattern provides additional information about the magnitude and relative sign between J(HH) and (n)J(CH) coupling constants.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, 08193, Bellaterra, Catalonia, Spain
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Saurí J, Nolis P, Castañar L, Virgili A, Parella T. P.E.HSQMBC: simultaneous measurement of proton-proton and proton-carbon coupling constants. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 224:101-106. [PMID: 23069350 DOI: 10.1016/j.jmr.2012.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/10/2012] [Accepted: 09/17/2012] [Indexed: 06/01/2023]
Abstract
A long-range optimized P.E.HSQC experiment, named P.E.HSQMBC, is proposed for the simultaneous measurement of a complete set of homonuclear and heteronuclear coupling constants from a single 2D cross-peak. The sign and the magnitude of proton-proton coupling constants are measured along the direct dimension from the relative E.COSY-type multiplet pattern displacement due to the passive one-bond coupling constant splitting generated in the indirect dimension. On the other hand, long-range proton-carbon coupling constants are independently determined in the detected dimension from a traditional fitting analysis of antiphase multiplet patterns or, more conveniently, from the IPAP multiplet displacement obtained from extended HSQMBC experiments.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain
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Saurí J, Parella T. Efficient measurement of the sign and the magnitude of long-range proton-carbon coupling constants from a spin-state-selective HSQMBC-COSY experiment. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:717-721. [PMID: 22949157 DOI: 10.1002/mrc.3867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 07/04/2012] [Accepted: 08/06/2012] [Indexed: 06/01/2023]
Abstract
A spin state-selective Heteronuclear Single-Quantum Multiple-Bond Connectivities (HSQMBC-COSY) experiment is proposed to measure the sign and the magnitude of long-range proton-carbon coupling constants ((n)J(CH); n > 1) either for protonated or for non-protonated carbons in small molecules. The simple substitution of the selective 180° (1)H pulse in the original selHSQMBC pulse scheme by a hard one allows the simultaneous evolution of both proton-proton and proton-carbon coupling constants during the refocusing period and enables a final COSY transfer between coupled protons. The successful implementation of the IPAP principle leads to separate mixed-phase α/β cross-peaks from which (n)J(CH) values can be easily measured by analyzing their relative frequency displacements in the detected dimension.
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Affiliation(s)
- Josep Saurí
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193-Bellaterra, Barcelona, Spain
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Saurí J, Espinosa JF, Parella T. A Definitive NMR Solution for a Simple and Accurate Measurement of the Magnitude and the Sign of Small Heteronuclear Coupling Constants on Protonated and Non-Protonated Carbon Atoms. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Saurí J, Espinosa JF, Parella T. A definitive NMR solution for a simple and accurate measurement of the magnitude and the sign of small heteronuclear coupling constants on protonated and non-protonated carbon atoms. Angew Chem Int Ed Engl 2012; 51:3919-22. [PMID: 22411743 DOI: 10.1002/anie.201108959] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/06/2012] [Indexed: 11/11/2022]
Abstract
Simply successful: a proton-selective HSQMBC-TOCSY experiment can be used to measure small proton-carbon ((n)J(CH); n>1) coupling constants on both protonated and non-protonated carbon atoms. The method combines in a single pulse scheme all the benefits of the widely used HSQMBC and HSQC-TOCSY experiments. The magnitude and the sign of (n)J(CH) can be determined simply with excellent accuracy.
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Affiliation(s)
- Josep Saurí
- SeRMN, Universitat Autònoma de Barcelona, Spain
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