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Coote P, Bermel W, Arthanari H. Optimization of phase dispersion enables broadband excitation without homonuclear coupling artifacts. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 325:106928. [PMID: 33652210 PMCID: PMC8012116 DOI: 10.1016/j.jmr.2021.106928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/19/2021] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
In NMR spectroscopy, many specialized shaped pulses are available for broadband excitation, beyond the bandwidth of conventional high-powered hard pulses. These shaped pulses typically have long duration. However, long-duration pulses are unsuitable for spectra containing significant homonuclear couplings, such as polyfluorinated compounds in 19F NMR. J-coupling evolution during the excitation pulse leads to spectral artifacts and incorrect peak integrals. Here, we report an approach to optimal control pulse design which significantly reduces the pulse length required to excite large bandwidths of chemical shift frequencies. The target state phase is not chosen beforehand but is instead only constrained to be linearly dependent on offset frequency. The first-order phase of the target state is then treated as a free-variable, to be optimized at the same time as the RF waveform itself. The resulting spectra are easily phased using standard NMR processing software. We observe that the required pulse length is significantly shorter than for currently available in-phase excitation schemes. Spectral artifacts from homonuclear couplings are avoided. We also demonstrate that pure in-phase excitation can be obtained over the same bandwidth by appending two inversion pulses, at the expense of increased overall duration.
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Affiliation(s)
- Paul Coote
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA; Dana Farber Cancer Institute, Boston, MA, USA
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Silberstreifen 4, 76287 Rheinstetten, Germany
| | - Haribabu Arthanari
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA; Dana Farber Cancer Institute, Boston, MA, USA.
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Dal Poggetto G, Soares JV, Tormena CF. Selective Nuclear Magnetic Resonance Experiments for Sign-Sensitive Determination of Heteronuclear Couplings: Expanding the Analysis of Crude Reaction Mixtures. Anal Chem 2020; 92:14047-14053. [PMID: 32924438 PMCID: PMC7660590 DOI: 10.1021/acs.analchem.0c02976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
State-of-the-art nuclear magnetic resonance (NMR) selective experiments are capable of directly analyzing crude reaction mixtures. A new experiment named HD-HAPPY-FESTA yields ultrahigh-resolution total correlation subspectra, which are suitable for sign-sensitive determination of heteronuclear couplings, as demonstrated here by measuring the sign and magnitude for proton-fluorine couplings (JHF) from major and minor isomer products of a two-step reaction without any purification. Proton-fluorine couplings ranging from 51.5 to -2.6 Hz could be measured using HD-HAPPY-FESTA, with the smallest measured magnitude of 0.8 Hz. Experimental JHF values were used to identify the two fluoroketone intermediates and the four fluoroalcohol products. Results were rationalized and compared with the density functional theory (DFT) calculations. Experimental data were further compared with the couplings reported in the literature, where pure samples were analyzed.
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Affiliation(s)
- Guilherme Dal Poggetto
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
| | - João Vitor Soares
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
| | - Cláudio F Tormena
- Institute of Chemistry, University of Campinas (UNICAMP), PO BOX 6154, Campinas, São Paulo CEP 13083-970, Brazil
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Howe PWA. Recent developments in the use of fluorine NMR in synthesis and characterisation. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 118-119:1-9. [PMID: 32883447 DOI: 10.1016/j.pnmrs.2020.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 06/11/2023]
Abstract
A review of developments in fluorine NMR of relevance to synthesis, characterisation and industrial applications of small organic molecules. Developments considered include those in spectrometer technology, computational methods and pulse sequences. The review of 80 references outlines applications in areas of identification, quantitation, mixture analysis, reaction monitoring, environmental studies and fragment-based drug design.
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Affiliation(s)
- Peter W A Howe
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire RG42 6EY, UK.
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Castañar L, Moutzouri P, Barbosa TM, Tormena CF, Rittner R, Phillips AR, Coombes SR, Nilsson M, Morris GA. FESTA: An Efficient Nuclear Magnetic Resonance Approach for the Structural Analysis of Mixtures Containing Fluorinated Species. Anal Chem 2018; 90:5445-5450. [DOI: 10.1021/acs.analchem.8b00753] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Laura Castañar
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Pinelopi Moutzouri
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Thaís M. Barbosa
- Chemistry Institute, University of Campinas − UNICAMP, P.O. Box. 6154, 13083-970 Campinas, São Paulo, Brazil
| | - Claudio F. Tormena
- Chemistry Institute, University of Campinas − UNICAMP, P.O. Box. 6154, 13083-970 Campinas, São Paulo, Brazil
| | - Roberto Rittner
- Chemistry Institute, University of Campinas − UNICAMP, P.O. Box. 6154, 13083-970 Campinas, São Paulo, Brazil
| | - Andrew R. Phillips
- Pharmaceutical Sciences, IMED Biotech Unit, AstraZeneca, Macclesfield SK10 2NA, United Kingdom
| | - Steven R. Coombes
- Pharmaceutical Technology and Development, AstraZeneca, Silk Road Business Park, Macclesfield SK10 2NA, United Kingdom
| | - Mathias Nilsson
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Gareth A. Morris
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Moutzouri P, Kiraly P, Phillips AR, Coombes SR, Nilsson M, Morris GA. 13C Satellite-Free 1H NMR Spectra. Anal Chem 2017; 89:11898-11901. [PMID: 29083868 DOI: 10.1021/acs.analchem.7b03787] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new NMR experiment (Destruction of Interfering Satellites by Perfect Echo Low-pass filtration, DISPEL) is introduced that facilitates the analysis of low-level components in high dynamic range mixtures by suppressing one-bond 13C satellite signals in 1H spectra. Since the natural abundance of 13C is around 1.1%, these satellites appear at 0.54% of the intensity of a parent peak, mimicking and often masking impurity signals. The new experiment suppresses one-bond 13C satellite signals, with high efficiency, at negligible cost in signal-to-noise ratio, and over a wide range of one-bond coupling constants, without the need for broadband 13C decoupling.
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Affiliation(s)
- Pinelopi Moutzouri
- School of Chemistry, University of Manchester , Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Peter Kiraly
- School of Chemistry, University of Manchester , Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Andrew R Phillips
- Pharmaceutical Sciences, IMED Biotech Unit, AstraZeneca , Silk Road Business Park, Macclesfield, SK10 2NA, United Kingdom
| | - Steven R Coombes
- Pharmaceutical Technology and Development, AstraZeneca , Silk Road Business Park, Macclesfield, SK10 2NA, United Kingdom
| | - Mathias Nilsson
- School of Chemistry, University of Manchester , Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Gareth A Morris
- School of Chemistry, University of Manchester , Oxford Road, Manchester, M13 9PL, United Kingdom
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