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Crouch RC, Pelmuş M, Raab JG, Tischenko E, Frey M, Wang Y, Reibarkh M, Williamson RT, Martin GE. J-modulated 19 F- and 1 H-detected dual-optimized inverted 1 J CC 1,n-ADEQUATE: A universal ADEQUATE experiment. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2023; 61:169-179. [PMID: 36349476 DOI: 10.1002/mrc.5324] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
The recently reported 19 F-detected dual-optimized inverted 1 JCC 1,n-ADEQUATE experiment and the previously reported 1 H-detected version have been modified to incorporate J-modulation, making it feasible to acquire all 1,1- and 1,n-ADEQUATE correlations as well as 1 JCC and n JCC homonuclear scalar couplings in a single experiment. The experiments are demonstrated using N,N-dimethylamino-2,5,6-trifluoro-3,4-phthalonitrile and N,N-dimethylamino-3,4-phthalonitrile.
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Affiliation(s)
- Ronald C Crouch
- Analytical Instruments, JEOL USA Inc., Peabody, Massachusetts, USA
| | - Marius Pelmuş
- Department of Chemistry, Seton Hall University, South Orange, New Jersey, USA
| | - Jeffrey G Raab
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina, USA
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Evgeny Tischenko
- Analytical Instruments, JEOL USA Inc., Peabody, Massachusetts, USA
| | - Michael Frey
- Analytical Instruments, JEOL USA Inc., Peabody, Massachusetts, USA
| | - Yunyi Wang
- Analytical Research and Development, Merck and Co., Inc., Rahway, New Jersey, USA
| | - Mikhail Reibarkh
- Analytical Research and Development, Merck and Co., Inc., Rahway, New Jersey, USA
| | - R Thomas Williamson
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Gary E Martin
- Department of Chemistry, Seton Hall University, South Orange, New Jersey, USA
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Snyder DA. Covariance NMR: Theoretical concerns, practical considerations, contemporary applications and related techniques. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 122:1-10. [PMID: 33632414 DOI: 10.1016/j.pnmrs.2020.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/23/2020] [Accepted: 09/29/2020] [Indexed: 06/12/2023]
Abstract
The family of resolution enhancement and spectral reconstruction techniques collectively known as covariance NMR continues to expand, along with the list of applications for these techniques. Recent advances in covariance NMR include the utilization of covariance to reconstruct pure shift NMR spectra, and the growing use of covariance NMR in processing non-uniformly sampled data, especially in solid state NMR and metabolomics. This review describes theoretical and practical considerations for direct and indirect covariance NMR techniques, and summarizes recent additions to the covariance NMR family. The review also outlines some of the applications of covariance NMR, and places covariance NMR in the larger context of methods that use statistical and algebraic approaches to enhance and combine various kinds of spectroscopic data, including tensor-based approaches for multidimensional NMR and heterocovariance spectroscopy.
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Affiliation(s)
- David A Snyder
- Department of Chemistry, College of Science and Health, William Paterson University of NJ, United States.
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Fredi A, Nolis P, Cobas C, Parella T. Access to experimentally infeasible spectra by pure-shift NMR covariance. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:161-168. [PMID: 27494746 DOI: 10.1016/j.jmr.2016.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/14/2016] [Accepted: 07/21/2016] [Indexed: 06/06/2023]
Abstract
Covariance processing is a versatile processing tool to generate synthetic NMR spectral representations without the need to acquire time-consuming experimental datasets. Here we show that even experimentally prohibited NMR spectra can be reconstructed by introducing key features of a reference 1D CHn-edited spectrum into standard 2D spectra. This general procedure is illustrated with the calculation of experimentally infeasible multiplicity-edited pure-shift NMR spectra of some very popular homonuclear (ME-psCOSY and ME-psTOCSY) and heteronuclear (ME-psHSQC-TOCSY and ME-psHMBC) experiments.
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Affiliation(s)
- André Fredi
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Carlos Cobas
- Mestrelab Research, Santiago de Compostela, E-15706 A Coruña, Spain
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain.
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Fredi A, Nolis P, Cobas C, Martin GE, Parella T. Exploring the use of Generalized Indirect Covariance to reconstruct pure shift NMR spectra: Current Pros and Cons. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 266:16-22. [PMID: 27003379 DOI: 10.1016/j.jmr.2016.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/05/2016] [Accepted: 03/07/2016] [Indexed: 06/05/2023]
Abstract
The current Pros and Cons of a processing protocol to generate pure chemical shift NMR spectra using Generalized Indirect Covariance are presented and discussed. The transformation of any standard 2D homonuclear and heteronuclear spectrum to its pure shift counterpart by using a reference DIAG spectrum is described. Reconstructed pure shift NMR spectra of NOESY, HSQC, HSQC-TOCSY and HSQMBC experiments are reported for the target molecule strychnine.
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Affiliation(s)
- André Fredi
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Pau Nolis
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain
| | - Carlos Cobas
- Mestrelab Research, Santiago de Compostela, E-15706 A Coruña, Spain
| | - Gary E Martin
- NMR Structure Elucidation, Process & Analytical Chemistry, Merck & Co. Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, United States
| | - Teodor Parella
- Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain.
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5
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Palmer MR, Suiter CL, Henry GE, Rovnyak J, Hoch JC, Polenova T, Rovnyak D. Sensitivity of nonuniform sampling NMR. J Phys Chem B 2015; 119:6502-15. [PMID: 25901905 DOI: 10.1021/jp5126415] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Many information-rich multidimensional experiments in nuclear magnetic resonance spectroscopy can benefit from a signal-to-noise ratio (SNR) enhancement of up to about 2-fold if a decaying signal in an indirect dimension is sampled with nonconsecutive increments, termed nonuniform sampling (NUS). This work provides formal theoretical results and applications to resolve major questions about the scope of the NUS enhancement. First, we introduce the NUS Sensitivity Theorem in which any decreasing sampling density applied to any exponentially decaying signal always results in higher sensitivity (SNR per square root of measurement time) than uniform sampling (US). Several cases will illustrate this theorem and show that even conservative applications of NUS improve sensitivity by useful amounts. Next, we turn to a serious limitation of uniform sampling: the SNR by US decreases for extending evolution times, and thus total experimental times, beyond 1.26T2 (T2 = signal decay constant). Thus, SNR and resolution cannot be simultaneously improved by extending US beyond 1.26T2. We find that NUS can eliminate this constraint, and we introduce the matched NUS SNR Theorem: an exponential sampling density matched to the signal decay always improves the SNR with additional evolution time. Though proved for a specific case, broader classes of NUS densities also improve SNR with evolution time. Applications of these theoretical results are given for a soluble plant natural product and a solid tripeptide (u-(13)C,(15)N-MLF). These formal results clearly demonstrate the inadequacies of applying US to decaying signals in indirect nD-NMR dimensions, supporting a broader adoption of NUS.
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Affiliation(s)
- Melissa R Palmer
- †Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837, United States
| | - Christopher L Suiter
- ‡Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Geneive E Henry
- §Department of Chemistry, Susquehanna University, Selinsgrove, Pennsylvania 17837, United States
| | - James Rovnyak
- ∥Department of Mathematics, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Jeffrey C Hoch
- ⊥Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut 06030, United States
| | - Tatyana Polenova
- ‡Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - David Rovnyak
- †Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837, United States
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Williamson RT, Buevich AV, Martin GE, Parella T. LR-HSQMBC: a sensitive NMR technique to probe very long-range heteronuclear coupling pathways. J Org Chem 2014; 79:3887-94. [PMID: 24708226 DOI: 10.1021/jo500333u] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
HMBC is one of the most often used and vital NMR experiments for the structure elucidation of organic and inorganic molecules. We have developed a new, high sensitivity NMR pulse sequence that overcomes the typical (2,3)JCH limitation of HMBC by extending the visualization of long-range correlation data to 4-, 5-, and even 6-bond long-range (n)JCH heteronuclear couplings. This technique should prove to be an effective experiment to complement HMBC for probing the structure of proton-deficient molecules. The LR-HSQMBC NMR experiment can, in effect, extend the range of HMBC to provide data similar to that afforded by 1,n-ADEQUATE even in sample-limited situations. This is accomplished by optimizing responses for very small (n)JCH coupings as opposed to relying on the markedly less sensitive detection of long-range coupled (13)C-(13)C homonuclear pairs at natural abundance. DFT calculations were employed to determine whether the very long-range correlations observed for cervinomycin A2 were reasonable on the basis of the calculated long-range couplings.
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Affiliation(s)
- R Thomas Williamson
- Discovery & Preclinical Sciences, Process & Analytical Chemistry, Structure Elucidation Group, Merck & Co. Inc. , Rahway, New Jersey 07065, United States
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Reibarkh M, Williamson RT, Martin GE, Bermel W. Broadband inversion of 1J(CC) responses in 1,n-ADEQUATE spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 236:126-133. [PMID: 24035003 DOI: 10.1016/j.jmr.2013.07.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/27/2013] [Accepted: 07/29/2013] [Indexed: 06/02/2023]
Abstract
Establishing the carbon skeleton of a molecule greatly facilitates the process of structure elucidation, both manual and computer-assisted. Recent advances in the family of ADEQUATE experiments demonstrated their potential in this regard. 1,1-ADEQUATE, which provides direct (13)C-(13)C correlation via (1)J(CC), and 1,n-ADEQUATE, which typically yields (3)J(CC) and (1)J(CC) correlations, are more sensitive and more widely applicable experiments than INADEQUATE and PANACEA. A recently reported modified pulse sequence that semi-selectively inverts (1)J(CC) correlations in 1,n-ADEQUATE spectra provided a significant improvement, allowing (1)J(CC) and (n)J(CC) correlations to be discerned in the same spectrum. However, the reported experiment requires a careful matching of the amplitude transfer function with (1)J(CC) coupling constants in order to achieve the inversion, and even then some (1)J(CC) correlations could still have positive intensity due to the oscillatory nature of the transfer function. Both shortcomings limit the practicality of the method. We now report a new, dual-optimized inverted (1)J(CC) 1,n-ADEQUATE experiment, which provides more uniform inversion of (1)J(CC) correlations across the range of 29-82 Hz. Unlike the original method, the dual optimization experiment does not require fine-tuning for the molecule's (1)J(CC) coupling constant values. Even more usefully, the dual-optimized version provides up to two-fold improvement in signal-to-noise for some long-range correlations. Using modern, cryogenically-cooled probes, the experiment can be successfully applied to samples of ~1 mg under favorable circumstances. The improvements afforded by dual optimization inverted (1)J(CC) 1,n-ADEQUATE experiment make it a useful and practical tool for NMR structure elucidation and should facilitate the implementation and utilization of the experiment.
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Affiliation(s)
- Mikhail Reibarkh
- Merck Research Laboratories, Discovery and Preclinical Sciences, Process and Analytical Chemistry, Structure Elucidation Group, Rahway, NJ 07065, USA.
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Martin GE, Buevich AV, Reibarkh M, Singh SB, Ondeyka JG, Williamson RT. Coniothyrione: anatomy of a structure revision. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:383-390. [PMID: 23674343 DOI: 10.1002/mrc.3952] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 06/02/2023]
Abstract
Coniothyrione is a xanthone-derived antibiotic reported several years ago by researchers at Merck & Co. Inc. Revision of the position of the chloro substitution was recently proposed on the basis of empirical reinterpretation of the carbon chemical shift data and a hypothetical biosynthetic argument without the acquisition of any new spectral data to support the postulated change in substituent location. The originally published HMBC data lead to an equivocal assignment of the structure and do not provide a solid basis of support for either structure. Neural network (13)C chemical shift calculations and density functional theory calculations also led to undifferentiated structures. Definitive confirmation of the structure of coniothyrione based on the acquisition and interpretation of 1,1-ADEQUATE and inverted (1)J(CC) 1,n-ADEQUATE data is now reported.
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Affiliation(s)
- Gary E Martin
- Merck Research Laboratories Discovery and Preclinical Sciences-Global Chemistry, Process and Analytical Chemistry, Structure Elucidation Group Summit, NJ 07065, USA
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Abstract
Over the past 28 years there have been several thousand publications describing the use of 2D NMR to identify and characterize natural products. During this time period, the amount of sample needed for this purpose has decreased from the 20-50 mg range to under 1 mg. This has been due to both improvements in NMR hardware and methodology. This review will focus on mainly methodology improvements, particularly in pulse sequences, acquisition and processing methods which are particularly relevant to natural product research, with lesser discussion of hardware improvements.
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Martin GE, Blinov KA, Williamson RT. HMBC-1,n-ADEQUATE spectra calculated from HMBC and 1,n-ADEQUATE spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:299-307. [PMID: 23483673 DOI: 10.1002/mrc.3946] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 01/30/2013] [Accepted: 02/06/2013] [Indexed: 06/01/2023]
Abstract
Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1-, 1,n-, and inverted (1)J(CC) 1,n-ADEQUATE spectra to afford carbon-carbon correlation spectra that allow the extraction of direct ((1)J(CC)), long-range ((n)J(CC), where n ≥ 2), and (1)J(CC)-edited long-range correlation data, respectively. Covariance processing of HMBC and 1,1-ADEQUATE spectra has also recently been reported, allowing convenient, high-sensitivity access to (n)J(CC) correlation data equivalent to the much lower sensitivity n,1-ADEQUATE experiment. Furthermore, HMBC-1,1-ADEQUATE correlations are observed in the F1 frequency domain at the intrinsic chemical shift of the (13)C resonance in question rather than at the double-quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n-ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n-ADEQUATE spectra is now reported. The resulting HMBC-1,n-ADEQUATE spectrum affords long-range carbon-carbon correlation data equivalent to the very low sensitivity m,n-ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC-1,n-ADEQUATE spectrum are again detected at the intrinsic (13)C chemical shifts of the correlated carbons rather than at the double-quantum frequency of the pair of correlated carbons. HMBC-1,n-ADEQUATE spectra can provide correlations ranging from diagonal ((0)J(CC) or diagonal correlations) to (4)J(CC) under normal circumstances to as much as (6)J(CC) in rare instances. The experiment affords the potential means of establishing the structures of severely proton-deficient molecules.
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Affiliation(s)
- Gary E Martin
- Discovery and Preclinical Sciences, Process and Analytical Chemistry, Structure Elucidation Group, Merck Research Laboratories, Summit, NJ 07901, USA.
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