1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Huang C, Peng Y, Lin E, Ni Z, Lin X, Zhan H, Huang Y, Chen Z. Adaptable Singlet-Filtered Nuclear Magnetic Resonance Spectroscopy for Chemical and Biological Applications. Anal Chem 2022; 94:4201-4208. [PMID: 35238535 DOI: 10.1021/acs.analchem.1c04210] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton nuclear magnetic resonance (1H NMR) spectroscopy presents a powerful detection tool for studying chemical compositions and molecular structures. In practical chemical and biological applications, 1H NMR experiments are generally confronted with the challenge of spectral congestions caused by abundant observable components and intrinsic limitations of a narrow frequency distribution range and extensive J coupling splitting. Herein, a one-dimensional (1D) general NMR method is proposed to individually extract the signals of targeted proton groups based on their endogenous spin singlet states excited from J coupling interactions, and it is suitable for high-resolution detections on complex chemical and biological samples. The applicability of the proposed method is demonstrated by experimental observations on chemical solutions containing different coupled components, intact grape tissues subjected to crowded resonances, and in vitro pig brain with various metabolites. Moreover, the proposed method is further exploited for magnetic resonance spectroscopy applications by directly combining the spatial localization module, showing promise in in vivo biological metabolite studies.
Collapse
Affiliation(s)
- Chengda Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China
| | - Yang Peng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China
| | - Enping 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, Siming South Road 422, Xiamen 361005, China
| | - Zhikai Ni
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China
| | - Xiaoqing 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, Siming South Road 422, Xiamen 361005, China
| | - Haolin Zhan
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 361005, China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Siming South Road 422, Xiamen 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, Siming South Road 422, Xiamen 361005, China
| |
Collapse
|
3
|
Nazarski RB. Summary of DFT calculations coupled with current statistical and/or artificial neural network (ANN) methods to assist experimental NMR data in identifying diastereomeric structures. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2020.152548] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
4
|
Moreno A, Hansen KØ, Isaksson J. CSSF-CLIP-HSQMBC: measurement of heteronuclear coupling constants in severely crowded spectral regions. RSC Adv 2019; 9:36082-36087. [PMID: 35540578 PMCID: PMC9074913 DOI: 10.1039/c9ra04118d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/18/2019] [Indexed: 11/21/2022] Open
Abstract
A new pulse program development, a chemical shift selective filtration clean in-phase HSQMBC (CSSF-CLIP-HSQMBC), is presented for the user-friendly measurement of long-range heteronuclear coupling constants in severely crowded spectral regions. The introduction of the chemical shift selective filter makes the experiment extremely efficient at resolving overlapped multiplets and produces a clean selective CLIP-HSQMBC spectrum, in which the desired coupling constants can easily be measured as an extra proton-carbon splitting in f2. The pulse sequence is also provided as a real-time homonuclear decoupled version in which the heteronuclear coupling constant can be directly measured as the peak splitting in f2. The same principle is readily applicable to IPAP and AP versions of the same sequence as well as the optional TOCSY transfer, or in principle to any other selective heteronuclear experiment that relies on a clean 1H multiplet.
Collapse
Affiliation(s)
- Aitor Moreno
- Bruker BioSpin AG, Application Science Department CH-8117 Fällanden Switzerland
| | - Kine Østnes Hansen
- Marbio, UiT - The Arctic University of Norway Breivika NO-9037 Tromsø Norway
| | - Johan Isaksson
- Department of Chemistry, UiT - The Arctic University of Norway Breivika NO-9037 Tromsø Norway
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Bigler P, Furrer J. Why is HMBC superior to LR-HSQC? Influence of homonuclear couplings J HH' on the intensity of long-range correlations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:1101-1116. [PMID: 29907970 DOI: 10.1002/mrc.4762] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/16/2018] [Accepted: 06/05/2018] [Indexed: 06/08/2023]
Abstract
Long-range heteronuclear single quantum correlation (LR-HSQC) experiments may be applied as an alternative to heteronuclear multiple-bond correlation (HMBC) experiments for detecting long-range correlations but has never enjoyed popularity for that purpose. To the best of our knowledge, the exact reasons have not yet been fully established. For both experiments, it is widely accepted that the evolution of proton-proton homonuclear couplings JHH' during the polarization transfer delays Δ leads to significant losses, and that the intensity of the observable coherence is zero when JHH' matches the condition Δ = 0.5/JHH' . Here, we analyze the influence of JHH' on the intensity of long-range correlations in HMBC and LR-HSQC spectra. We show that for both experiments long-range correlations will not be canceled because of homonuclear couplings JHH' . Our theoretical and experimental results definitely establish and validate the superiority of HMBC-based experiments among the family of heteronuclear long-range correlation experiments: (a) the overall cross peak's intensity is higher, and (b) in LR-HSQC experiments, the intensity of the long-range cross peaks is additionally influenced in an unwanted way by the magnitude and number of passive homonuclear proton-proton couplings JHH' .
Collapse
Affiliation(s)
- Peter Bigler
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012, Bern, Switzerland
| | - Julien Furrer
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012, Bern, Switzerland
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Adamson J, Nazarski RB, Jarvet J, Pehk T, Aav R. Shortfall of B3LYP in Reproducing NMR J
CH
Couplings in Some Isomeric Epoxy Structures with Strong Stereoelectronic Effects: A Benchmark Study on DFT Functionals. Chemphyschem 2018; 19:631-642. [DOI: 10.1002/cphc.201701125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/17/2017] [Indexed: 01/13/2023]
Affiliation(s)
- Jasper Adamson
- National Institute of Chemical Physics and Biophysics; Akadeemia tee 23 12618 Tallinn Estonia
| | - Ryszard B. Nazarski
- Theoretical and Structural Chemistry Group; Department of Physical Chemistry; Faculty of Chemistry; University of Lodz; Pomorska 163/165 90-236 Łódź Poland
| | - Jüri Jarvet
- National Institute of Chemical Physics and Biophysics; Akadeemia tee 23 12618 Tallinn Estonia
- Current address: Department of Biochemistry and Biophysics; Arrhenius Laboratories; Stockholm University; Svante Arrhenius väg 16 10691 Stockholm Sweden
| | - Tõnis Pehk
- National Institute of Chemical Physics and Biophysics; Akadeemia tee 23 12618 Tallinn Estonia
| | - Riina Aav
- Department of Chemistry and Biotechnology; Tallinn University of Technology; Akadeemia tee 15 12618 Tallinn Estonia
| |
Collapse
|
9
|
Tan C, Cai S, Huang Y. Spatially Localized Two-Dimensional J-Resolved NMR Spectroscopy via Intermolecular Double-Quantum Coherences for Biological Samples at 7 T. PLoS One 2015. [PMID: 26207739 PMCID: PMC4514627 DOI: 10.1371/journal.pone.0134109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Background and Purpose Magnetic resonance spectroscopy (MRS) constitutes a mainstream technique for characterizing biological samples. Benefiting from the separation of chemical shifts and J couplings, spatially localized two-dimensional (2D) J-resolved spectroscopy (JPRESS) shows better identification of complex metabolite resonances than one-dimensional MRS does and facilitates the extraction of J coupling information. However, due to variations of macroscopic magnetic susceptibility in biological samples, conventional JPRESS spectra generally suffer from the influence of field inhomogeneity. In this paper, we investigated the implementation of the localized 2D J-resolved spectroscopy based on intermolecular double-quantum coherences (iDQCs) on a 7 T MRI scanner. Materials and Methods A γ-aminobutyric acid (GABA) aqueous solution, an intact pig brain tissue, and a whole fish (Harpadon nehereus) were explored by using the localized iDQC J-resolved spectroscopy (iDQCJRES) method, and the results were compared to those obtained by using the conventional 2D JPRESS method. Results Inhomogeneous line broadening, caused by the variations of macroscopic magnetic susceptibility in the detected biological samples (the intact pig brain tissue and the whole fish), degrades the quality of 2D JPRESS spectra, particularly when a large voxel is selected and some strongly structured components are included (such as the fish spinal cord). By contrast, high-resolution 2D J-resolved information satisfactory for metabolite analyses can be obtained from localized 2D iDQCJRES spectra without voxel size limitation and field shimming. From the contrastive experiments, it is obvious that the spectral information observed in the localized iDQCJRES spectra acquired from large voxels without field shimming procedure (i.e. in inhomogeneous fields) is similar to that provided by the JPRESS spectra acquired from small voxels after field shimming procedure (i.e. in relatively homogeneous fields). Conclusion The localized iDQCJRES method holds advantage for recovering high-resolution 2D J-resolved information from inhomogeneous fields caused by external non-ideal field condition or internal macroscopic magnetic susceptibility variations in biological samples, and it is free of voxel size limitation and time-consuming field shimming procedure. This method presents a complementary way to the conventional JPRESS method for MRS measurements on MRI systems equipped with broad inner bores, and may provide a promising tool for in vivo MRS applications.
Collapse
Affiliation(s)
- Chunhua Tan
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, China
| | - Shuhui Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, China
| | - Yuqing Huang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, China
- * E-mail:
| |
Collapse
|
10
|
Huang Y, Cai S, Zhang Z, Chen Z. High-resolution two-dimensional J-resolved NMR spectroscopy for biological systems. Biophys J 2014; 106:2061-70. [PMID: 24806938 PMCID: PMC4017288 DOI: 10.1016/j.bpj.2014.03.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 03/13/2014] [Accepted: 03/14/2014] [Indexed: 11/19/2022] Open
Abstract
NMR spectroscopy is a principal tool in metabolomic studies and can, in theory, yield atom-level information critical for understanding biological systems. Nevertheless, NMR investigations on biological tissues generally have to contend with field inhomogeneities originating from variations in macroscopic magnetic susceptibility; these field inhomogeneities broaden spectral lines and thereby obscure metabolite signals. The congestion in one-dimensional NMR spectra of biological tissues often leads to ambiguities in metabolite identification and quantification. We propose an NMR approach based on intermolecular double-quantum coherences to recover high-resolution two-dimensional (2D) J-resolved spectra from inhomogeneous magnetic fields, such as those created by susceptibility variations in intact biological tissues. The proposed method makes it possible to acquire high-resolution 2D J-resolved spectra on intact biological samples without recourse to time-consuming shimming procedures or the use of specialized hardware, such as magic-angle-spinning probes. Separation of chemical shifts and J couplings along two distinct dimensions is achieved, which reduces spectral crowding and increases metabolite specificity. Moreover, the apparent J coupling constants observed are magnified by a factor of 3, facilitating the accurate measurement of small J couplings, which is useful in metabolic analyses. Dramatically improved spectral resolution is demonstrated in our applications of the technique on pig brain tissues. The resulting spectra contain a wealth of chemical shift and J-coupling information that is invaluable for metabolite analyses. A spatially localized experiment applied on an intact fish (Crossocheilus siamensis) reveals the promise of the proposed method in in vivo metabolite studies. Moreover, the proposed method makes few demands on spectrometer hardware and therefore constitutes a convenient and effective manner for metabonomics study of biological systems.
Collapse
Affiliation(s)
- Yuqing Huang
- 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, China
| | - Shuhui Cai
- 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, China
| | - Zhiyong Zhang
- 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, 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, China.
| |
Collapse
|
11
|
Pendrill R, Sørensen OW, Widmalm G. Suppressing one-bond homonuclear 13C,13C scalar couplings in the J-HMBC NMR experiment: application to 13C site-specifically labeled oligosaccharides. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:82-86. [PMID: 24395678 DOI: 10.1002/mrc.4038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/10/2013] [Accepted: 12/04/2013] [Indexed: 06/03/2023]
Abstract
Site-specific (13)C isotope labeling is a useful approach that allows for the measurement of homonuclear (13)C,(13)C coupling constants. For three site-specifically labeled oligosaccharides, it is demonstrated that using the J-HMBC experiment for measuring heteronuclear long-range coupling constants is problematical for the carbons adjacent to the spin label. By incorporating either a selective inversion pulse or a constant-time element in the pulse sequence, the interference from one-bond (13)C,(13)C scalar couplings is suppressed, allowing the coupling constants of interest to be measured without complications. Experimental spectra are compared with spectra of a nonlabeled compound as well as with simulated spectra. The work extends the use of the J-HMBC experiments to site-specifically labeled molecules, thereby increasing the number of coupling constants that can be obtained from a single preparation of a molecule.
Collapse
Affiliation(s)
- Robert Pendrill
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91, Stockholm, Sweden
| | | | | |
Collapse
|
12
|
Chaudhari SR, Suryaprakash N. Pure shift NMR approach for fast and accurate extraction of heteronuclear couplings. RSC Adv 2014. [DOI: 10.1039/c4ra01436g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An NMR experiment for the direct determination of heteronuclear couplings from the severely overlapped 1H NMR spectrum.
Collapse
Affiliation(s)
- Sachin Rama Chaudhari
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012, India
| | - N. Suryaprakash
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012, India
| |
Collapse
|
13
|
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.
Collapse
Affiliation(s)
- Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
| | | |
Collapse
|
14
|
Saurí J, Parella T, Espinosa JF. CLIP-HSQMBC: easy measurement of small proton–carbon coupling constants in organic molecules. Org Biomol Chem 2013; 11:4473-8. [DOI: 10.1039/c3ob40675j] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
15
|
Chaudhari SR, Nath N, Suryaprakash N. C-HETSERF: distinction of cis/trans-isomers and measurement of long range couplings between chemically equivalent nuclei in polycyclic aromatic hydrocarbons. RSC Adv 2012. [DOI: 10.1039/c2ra21898d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|