Magnetic Resonance in Chemistry

Cover image for Vol. 54 Issue 3

Early View (Online Version of Record published before inclusion in an issue)

Impact Factor: 1.179

ISI Journal Citation Reports © Ranking: 2014: 30/44 (Spectroscopy); 94/157 (Chemistry Multidisciplinary); 107/139 (Chemistry Physical)

Online ISSN: 1097-458X


  1. 1 - 46
  1. Research articles

    1. Generic applications of 13C-detected NMR diffusion to formulated systems with suppression of thermal convection induced by proton decoupling

      Jianbo Hou, Yiyong He, Paolo Sabatino, Ling Yuan and David Redwine

      Article first published online: 4 FEB 2016 | DOI: 10.1002/mrc.4404

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      Effective suppression of thermal convection effect is critical to enable robust applications of 13C-detected diffusion to formulated systems in general.

    2. Observation of potentially troublesome 2JCC correlations in 1,1-ADEQUATE spectra

      Josep Saurí, Yizhou Liu, R. Thomas Williamson and Gary E. Martin

      Article first published online: 4 FEB 2016 | DOI: 10.1002/mrc.4385

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      Certain large nJCC couplings, in particular, the 2JCC coupling across a carbonyl, can lead to observable cross peaks in 1,1-ADEQUATE spectra, and to strong correlations due to the enhanced sensitivity afforded by 1,1-HD-ADEQUATE. Therefore caution should be used during data interpretation of carbonyl containing compounds.

  2. Special issue research articles

    1. Isolation and structure elucidation of unexpected in-process impurities during tetrazole ring formation of an investigational drug substance

      Maria Victoria Silva Elipe, Chul Yoo, Fang Xia, Jason Simiens, Kevin Crossley, John R. Huckins, Hong-Xun Guo, Jason Tedrow and Kirby Wong-Moon

      Article first published online: 3 FEB 2016 | DOI: 10.1002/mrc.4413

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      Two in-process impurities of identical protonated mass of ca. 577.32 Da and fragmentation patterns were observed during the formation of the tetrazole ring in an intermediate of an investigational drug. A multi-step isolation procedure from the mother liquor of the reaction was performed for structural elucidation. NMR indicated the presence of an additional NH functional group in both isolates with similar spatial and bond correlations. The unexpected formation of a benzodimethylcarbamoylamino moiety appears to be resulting from a ‘Schmidt-like’ reaction.

  3. Research articles

    1. Characterization of novel isobenzofuranones by DFT calculations and 2D NMR analysis

      Milena G. Teixeira and Elson S. Alvarenga

      Article first published online: 26 JAN 2016 | DOI: 10.1002/mrc.4411

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      Phthalides are frequently found in naturally occurring substances and exhibit a broad spectrum of biological activities. In the search for compounds with insecticidal activity, phthalides have been used as versatile building blocks for the syntheses of novel potential agrochemicals. The endo Diels–Alder adduct (2) was brominated to afford two novel unforeseen compounds, which were characterized by comparing the experimental and theoretical 1H and 13C chemical shifts by mean absolute error and DP4 probability analyses.

    2. You have full text access to this OnlineOpen article
      High-resolution magic angle spinning 1H NMR measurement of ligand concentration in solvent-saturated chromatographic beads

      Fredrik Elwinger and István Furó

      Article first published online: 20 JAN 2016 | DOI: 10.1002/mrc.4370

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      The method obtains ligand concentration by relating the peak integrals for the ligand in the spectrum of a water-saturated chromatography medium to the integral of the added internal reference. The method is fast, precise, and accurate, the latter as indicated by the excellent agreement of concentration with that obtained by 13C SPE MAS NMR. Effects of radiofrequency field inhomogeneity, spin rate, temperature increase, and distribution of medium and reference solvent are investigated.

  4. Letter - spectral assignments

    1. Structure determination of two new nerolidol-type sesquiterpenoids from the soil actinomycete Streptomyces scopuliridis

      Liya Li, Ruohan Liu, Li Han, Yi Jiang, Jiang Liu, Yuanyuan Li, Chunhui Yuan and Xueshi Huang

      Article first published online: 18 JAN 2016 | DOI: 10.1002/mrc.4409

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      Two new nerolidol-type sesquiterpenes were isolated from the culture broth of Streptomyces scopuliridis, and identified based on 1D and 2D NMR spectroscopic data analyses.

  5. Research articles

    1. Isotopic splitting patterns in the 13C NMR spectra of some partially deuterated 1-aryl-2-(phenyldiazenyl)butane-1,3-dione and 4-hydroxy-3-(phenyldiazenyl)-2H-chromen-2-one: evidence for elucidation of tautomeric forms

      Nader Noroozi Pesyan and Hamid Rashidnejad

      Article first published online: 18 JAN 2016 | DOI: 10.1002/mrc.4390

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      Isotopic splitting patterns in the 13C nuclear magnetic resonance spectra of some partially deuterated 1-aryl-2-(phenyldiazenyl)butane-1,3-dione and 4-hydroxy-3-(phenyldiazenyl)-2H-chromen-2-one were investigated: CDCl3 and/or DMSO-d6 with addition of two drops of D2O. All dyes showed intramolecular hydrogen bonding. Among ten dye samples, two dyes derived from benzoylacetone did not show deuteration, three dyes showed partial deuteration and five dyes showed full deuteration under similar conditions.

    2. Distinguishing rotamers in N-trifluoroacetyl-3-benzazepine derivatives

      Williams A. Acevedo-Fuentes and Bruce K. Cassels

      Article first published online: 13 JAN 2016 | DOI: 10.1002/mrc.4406

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      This paper provides the full 13C NMR assignments for the trifluoroacetamides of five potentially appetite-reducing 5-HT2C benzazepine receptor agonists and two open-ring synthetic precursors. These compounds exist in solution as mixtures of two rotamers for each of which the 13C NMR signals have now been assigned with the assistance of 2D NMR experiments and the carbonyl-induced shifts of the neighboring 13CH2 resonances and long-range 13C/19F couplings.

  6. Special issue research articles

    1. Di(ethylene glycol) methyl ether methacrylate (DEGMEMA)-derived gels align small organic molecules in methanol

      Manuela E. García, Shannon R. Woodruff, Erich Hellemann, Nicolay V. Tsarevsky and Roberto R. Gil

      Article first published online: 13 JAN 2016 | DOI: 10.1002/mrc.4400

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      In this study, di(ethylene glycol) methyl ether methacrylate (DEGMEMA)-based gels are introduced as alignment media for the measurement of RDCs of small organic molecules in polar solvents such as methanol. The low viscosity of methanol permits the execution of J- scaled BIRD HSQC experiments that yield very sharp lines in anisotropic conditions. The gels have excellent mechanical properties and performance demonstrated by analyzing the structure of the alkaloid retrorsine.

  7. Research articles

    1. Q.E.COSY: determining sign and size of small deuterium residual quadrupolar couplings using an extended E.COSY principle

      Pavleta Tzvetkova and Burkhard Luy

      Article first published online: 13 JAN 2016 | DOI: 10.1002/mrc.4386

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      The Q.E.COSY as an extension of the E.COSY principle allows the sign sensitive measurement of residual quadrupolar couplings in partially aligned samples even in cases where corresponding splittings are not resolved in the deuterium 1D spectrum. Several experimental demonstrations are given.

    2. Evaluation of the surface affinity of water in three biochars using fast field cycling NMR relaxometry

      Salvatore Bubici, Jean-Pierre Korb, Jiří Kučerik and Pellegrino Conte

      Article first published online: 11 JAN 2016 | DOI: 10.1002/mrc.4391

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      Hopping and residence times of water on biochar surface have been measured by fast field cycling NMR relaxometry. These were related to biochar wettability. NMR results accorded with those from contact angle measurements, thereby indicating that the former technique is a valid alternative to the latter. Advantage of relaxometry over contact angle measurements lies in the possibility to obtain not only wettability, but also mechanisms of water molecular dynamics on biochar surface, thereby leading to the understanding of its role in increasing soil quality and plant nutrition.

    3. Conformation analysis of d-glucaric acid in deuterium oxide by NMR based on its JHH and JCH coupling constants

      Yukiko Enomoto-Rogers, Hisaharu Masaki, Tetsuya Ito, Kazuo Furihata and Tadahisa Iwata

      Article first published online: 8 JAN 2016 | DOI: 10.1002/mrc.4396

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      Conformation of d-glucaric acid (GA), in deuterium oxide was analyzed by NMR, based on J-resolved conformation analysis using proton–proton (3JHH) and proton–carbon (2JCH and 3JCH) coupling constants, as well as nuclear overhauser effect spectroscopy. It was suggested that there were three dominant conformers of GA in equilibrium with each other, including conformer (1 (H2H3:gauche, H3H4:anti, and H4H5:gauche), conformer 2 (H2H3:gauche, H3H4:anti, and H4H5:anti), and conformer 3 (H2H3:gauche, H3H4:gauche and H4H5:anti). Conformational structures of GA in solution were ‘bent’ rather than being fully extended.

  8. Special issue research articles

    1. Selective diffusion spectroscopy using excitation sculpting

      Peter W.  A. Howe

      Article first published online: 28 DEC 2015 | DOI: 10.1002/mrc.4402

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      The excitation sculpting pulse sequence provides a robust, reproducible and sensitive method for measuring the diffusion coefficients of minor components in complex mixtures.

  9. Research articles

    1. Powder-XRD and 14N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides

      Pierre Kempgens and Jonathan Britton

      Article first published online: 21 DEC 2015 | DOI: 10.1002/mrc.4395

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      TiN, ZrN, InN, GaN, Ca3N2, Mg3N2 and Ge3N4 have been studied by powder-XRD and 14N MAS NMR spectroscopy. The 14N MAS NMR spectra are symmetric and dominated by the quadrupolar interaction. The Lorentzian envelope of the spinning sidebands manifold can only be explained by a distribution of quadupolar coupling constants.

  10. Reviews

    1. Characterization of fast-tumbling isotropic bicelles by PFG diffusion NMR

      Jobst Liebau, Weihua Ye and Lena Mäler

      Article first published online: 14 DEC 2015 | DOI: 10.1002/mrc.4399

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      Small, isotropic bicelles are suitable for solution-state NMR and contain a lipid bilayer and the lipid composition is flexible. Diffusion coefficients can be measured by pulsed-field gradient NMR methods and can be used to assess bicelle size and morphology. Also, association of molecules to bicelles can be assessed by this method.

  11. Research articles

    1. Synthesis of a new quaternary phosphonium salt: NMR study of the conformational structure and dynamics

      Oksana V. Aganova, Leysan F. Galiullina, Albert V. Aganov, Nikita V. Shtyrlin, Mikhail V. Pugachev, Alexey D. Strel'nik, Sergey A. Koshkin, Yurii G. Shtyrlin and Vladimir V. Klochkov

      Article first published online: 14 DEC 2015 | DOI: 10.1002/mrc.4378

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      Schematic presentation of the conformational exchange in compound 3 caused by the rotation of the CH2-14-P+(Ph)3 and CH2-16-P+(Ph)3 groups around C5―C14 and C4―16 bonds, respectively.

    2. 1H-NMR relaxometric studies of interaction between apoptosis specific MRI paramagnetic contrast agents and micellar models of apoptotic cells

      Aurore Van Koninckxloo, Céline Henoumont, Sophie Laurent, Robert N. Muller and Luce Vander Elst

      Article first published online: 9 DEC 2015 | DOI: 10.1002/mrc.4397

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      Two specific hexapeptides targeting apoptosis are grafted to contrast agents (CA). We use micelles as model of apoptotic cells to investigate in vitro the interaction between grafted peptides and apoptotic cells. They are mimicking by 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine micelles and healthy cells by1,2-dipalmitoyl-sn-glycero-3-phosphocholine micelles (negative control). A ‘hump’ at high field on nuclear magnetic relaxation dispersion profiles reveals a potential interaction between micelles mimicking apoptotic cells and Gd-complexes as confirmed by transverse relaxivities measured at 60 MHz.

  12. Letter - spectral assignments

    1. Bioactive Nitrogenous Compounds from Acorus tatarinowii

      Xiao-Lin Feng, Hai-Bo Li, Hao Gao, Yan Huang, Wen-Xia Zhou, Yang Yu and Xin-Sheng Yao

      Article first published online: 7 DEC 2015 | DOI: 10.1002/mrc.4393

  13. Mini-reviews

    1. 1H and 13C NMR data on natural and synthetic capsaicinoids

      Víctor Gómez-Calvario, María Luisa Garduño-Ramírez, Ismael León-Rivera and María Yolanda Rios

      Article first published online: 2 DEC 2015 | DOI: 10.1002/mrc.4382

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      Capsaicinoids are the compounds responsible for the pungency of chili peppers. These substances also exhibit antinociceptive, analgesic, anti-inflammatory, and antiobesity properties. This review summarizes the 1H and 13C NMR data on 159 natural and synthetic capsaicinoids, with a brief discussion of typical and relevant aspects of these NMR data.

  14. Letter - spectral assignments

    1. New ring-rearranged metabolite of 20-hydroxyecdysone obtained by base-catalyzed auto-oxidation

      Tamás Gáti, András Simon, Attila Hunyadi, József Csábi, Zoltán Kele and Gábor Tóth

      Article first published online: 23 NOV 2015 | DOI: 10.1002/mrc.4389

    2. 1H and 13C NMR spectral assignments of novel flavonoids bearing benzothiazepine

      Seunghyun Ahn, Soon Young Shin, Yearam Jung, Hyeryoung Jung, Beom Soo Kim, Dongsoo Koh and Yoongho Lim

      Article first published online: 23 NOV 2015 | DOI: 10.1002/mrc.4388

  15. Research articles

    1. Ethanol determination in frozen fruit pulps: an application of quantitative nuclear magnetic resonance

      Wilian da Silva Nunes, Caroline Silva de Oliveira and Glaucia Braz Alcantara

      Article first published online: 18 NOV 2015 | DOI: 10.1002/mrc.4383

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      Nuclear Magnetic Resonance (NMR) was applied for analyzing the metabolic profile and quantifying the ethanol content in fruit pulps.

      The ethanol content in some industrial pulps is above the level recommended by regulatory agencies and is near the levels of some homemade pulps post-ripening.

      Quantitative NMR can be used to rapidly detect ethanol content in frozen fruit pulps.

    2. Solid-state NMR characterization of tri-ethyleneglycol grafted polyisocyanopeptides

      T. Zinkevich, B. Venderbosch, M. Jaspers, P. H. J. Kouwer, A. E. Rowan, E. R. H. van Eck and A. P. M. Kentgens

      Article first published online: 12 NOV 2015 | DOI: 10.1002/mrc.4379

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      The structure of polyisocyanopeptide is investigated by solid-state NMR spectroscopy. We revealed an existence of two conformations in equal ratios. The origin of these conformations is discussed.

  16. Special issue research articles

    1. NMR characterization of novel pyranoanthocyanins derived from the pulp of Panax quinquefolius L. (North American ginseng)

      Mark H. Nabuurs, Jason L. McCallum, Daniel C. Brown and Christopher W. Kirby

      Article first published online: 5 NOV 2015 | DOI: 10.1002/mrc.4366

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      Three major pigments were determined to be present in the berry pulp of Panax quinquefolius L. They were pelargonidin 3-O-lathyroside along with two novel pyranoanthocyanins with the same disaccharide attached at the 3-O position. In the tradition of naming novel anthocyanin aglycones based on botanical origin, the new pyranoanthocyanin aglycones have been given the common names Panaxidin A (pelaragonidin-4-vinylcatechol) and Panaxidin B (pelargonidin-4-vinylphenol).

  17. Research articles

    1. Synthesis of a new 1,2,3,4,5-pentasubstituted cyclohexanol and determining its stereochemistry by NMR spectroscopy and quantum-chemical calculations

      Ibrahim Mamedov, Rza Abbasoglu, Musa Bayramov and Abel Maharramov

      Article first published online: 2 NOV 2015 | DOI: 10.1002/mrc.4377

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      The preferred chair conformation for the six-membered ring was confirmed by NMR and quantum-chemical calculations methods.

    2. Band-selective excited ultrahigh resolution PSYCHE-TOCSY: fast screening of organic molecules and complex mixtures

      Veera Mohana Rao Kakita, Sahithya Phani Babu Vemulapalli and Jagadeesh Bharatam

      Article first published online: 2 NOV 2015 | DOI: 10.1002/mrc.4376

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      1. Ultrahigh resolution PSYCHE-TOCSY scheme with band-selective excitation.
      2. Fast and routine screening of complex organic molecules/mixtures.
    3. Comparison of experimental and DFT-calculated NMR chemical shifts of 2-amino and 2-hydroxyl substituted phenyl benzimidazoles, benzoxazoles and benzothiazoles in four solvents using the IEF-PCM solvation model

      Gregory K. Pierens, T. K. Venkatachalam and David C. Reutens

      Article first published online: 19 OCT 2015 | DOI: 10.1002/mrc.4374

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      A comparative study of experimental and calculated NMR chemical shifts of six compounds comprising 2-amino and 2-hydroxy phenyl benzoxazoles/benzothiazoles/benzimidazoles in four solvents is reported. The largest chemical shift deviations were observed in benzene. The chemical shifts were calculated with density functional theory using a suite of four functionals and basis set combinations. The calculated and experimentally determined values revealed a good match.

  18. Special issue historical

  19. Research articles

    1. A detailed mechanistic investigation into the reaction of 3-methylpentanoic acid with Meldrum's acid utilizing online NMR spectroscopy

      Anna L. Dunn, Anna Codina, David A. Foley, Brian L. Marquez and Mark T. Zell

      Article first published online: 31 AUG 2015 | DOI: 10.1002/mrc.4317

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      A thorough investigation into the mechanism of the reaction of 3-methylpentanoic acid and Meldrum's acid using online NMR spectroscopy is reported. Structural characterization of a number of reaction species is presented, providing evidence of the productive intermediates to product formation.

  20. Special issue research articles

    1. Improving the performance of J-modulated ADEQUATE experiments through homonuclear decoupling and non-uniform sampling

      Josep Saurí, Teodor Parella, R. Thomas Williamson and Gary E. Martin

      Article first published online: 31 AUG 2015 | DOI: 10.1002/mrc.4322

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      Enhancement of J-modulated ADEQUATE experiments through homodecoupling (HD) and non-uniform sampling (NUS) are described. Sensitivity (s/n) is enhanced by homodecoupling and resolution in the F1 frequency domain is enhanced by the application of NUS. Improvements in the experiments can be exploited to save time or conversely to achieve higher s/n in the same time. The modifications facilitated the measurement of nJCC couplings of < 3 Hz with the J-modulated 1,n-HD-ADEQUATE sequence.

    2. NMR studies of dilithiostyrenes: aggregation, NMR parameters, and DFT calculations for (E)-1-Lithio-2-(o-lithiophenyl)-1-trimethylsilylethen

      Bernd Böhler, Harald Günther, Kerstin Reider, Adalbert Maercker, Dennis Gerbig and Heike Hausmann

      Article first published online: 6 AUG 2015 | DOI: 10.1002/mrc.4298

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      The NMR properties, the structure, and the dynamic behavior of a trimethylsilyl-substituted dilithiostyrene have been determined in solution.

    3. Reaction monitoring using online vs tube NMR spectroscopy: seriously different results

      David A. Foley, Anna L. Dunn and Mark T. Zell

      Article first published online: 6 AUG 2015 | DOI: 10.1002/mrc.4259

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      A kinetic rate analysis of three reaction processes reveals that rates derived from nuclear magnetic resonance (NMR) analysis are highly dependent on monitoring method. These findings indicate that users must be aware of the effect of their monitoring method upon the kinetic rate data derived from NMR analysis.

    4. Complete 1H NMR assignment of cedranolides

      Nury Perez-Hernandez, Barbara Gordillo-Roman, Daniel Arrieta-Baez, Carlos M. Cerda-Garcia-Rojas and Pedro Joseph-Nathan

      Article first published online: 1 JUL 2015 | DOI: 10.1002/mrc.4246

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      The complete 1H NMR assignment of ten members of the cedranolide family, including economically important α-cedrene and cedrol, is described using the iterative full spin analysis included in the PERCH NMR software (PERCH Solutions Ltd., Kuopio, Finland). The coupling constants were correlated with the conformational preferences of the cedranolides calculated using the complete basis set method.

    5. Investigation of the reaction of 1,3-dimethylurea with formaldehyde by quantitative on-line NMR spectroscopy: a model for the urea–formaldehyde system

      Oliver Steinhof, Günter Scherr and Hans Hasse

      Article first published online: 12 JUN 2015 | DOI: 10.1002/mrc.4274

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      Quantitative on-line NMR spectroscopy is applied to study the equilibria and the reaction kinetics of the reaction of formaldehyde with 1,3-dimethylurea. This reaction system is employed as a model system for the much more complex but industrially relevant urea–formaldehyde system. Detailed peak assignment data for 1H, 13C, and 15N and reaction kinetic and equilibrium data at industrially relevant reaction conditions including all model parameters and a detailed description of the model are provided.

  21. Special issue research article

    1. Relaxation NMR as a tool to study the dispersion and formulation behavior of nanostructured carbon materials

      David Fairhurst, Terence Cosgrove and Stuart W. Prescott

      Article first published online: 18 MAY 2015 | DOI: 10.1002/mrc.4218

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      Solvent relaxation NMR gives a measure of the surface areas and wettability of various nanostructured carbons including nano carbon blacks, graphene oxides, nanographites and porous graphenes. A range of solvents including water, ethanol and tetrahydrofuran can be used. Relaxation measurements are shown to give good results on opaque, concentrated dispersions directly from production. Differences in total surface area due to different milling processes can be observed as well as the negative impact of using excess dispersant.

  22. Special issue review

    1. Hyphenated low-field NMR techniques: combining NMR with NIR, GPC/SEC and rheometry

      Volker Räntzsch, Manfred Wilhelm and Gisela Guthausen

      Article first published online: 9 APR 2015 | DOI: 10.1002/mrc.4219

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      Hyphenated low-field NMR techniques are promising characterization methods for online process analytics and comprehensive offline studies of soft materials. In this review, we present a combination of near-infrared spectroscopy and time-domain NMR (TD-NMR) relaxometry, online 1H-NMR spectroscopy after size exclusion chromatographic (SEC, also known as GPC) separation and a combination of rheometry and TD-NMR relaxometry for highly viscous materials. Case studies are reviewed that underline the possibilities and challenges of the different methods.

  23. Special issue mini-reviews

    1. New applications and perspectives of fast field cycling NMR relaxometry

      Rebecca M. Steele, Jean-Pierre Korb, Gianni Ferrante and Salvatore Bubici

      Article first published online: 9 APR 2015 | DOI: 10.1002/mrc.4220

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      We will focus on the most recent developments in fast field cycling NMR relaxometry instrumentation and applications and future perspectives of how this technology will be applied in both academic and industrial contexts to study the molecular dynamics in a wide range of substances and materials or simply for fingerprinting or quality control purposes.

  24. Special issue research articles

    1. Automated data evaluation and modelling of simultaneous 19F–1H medium-resolution NMR spectra for online reaction monitoring

      Nicolai Zientek, Clément Laurain, Klas Meyer, Andrea Paul, Dirk Engel, Gisela Guthausen, Matthias Kraume and Michael Maiwald

      Article first published online: 9 APR 2015 | DOI: 10.1002/mrc.4216

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      The Calibration samples were analysed under stationary conditions. The flow rates in the monitoring experiments were slow enough to ensure entirely magnetised nuclei. Flow effects only influences the peak width which was compensated by the corresponding evaluation method.

    2. Simple 17O NMR method for studying electron self-exchange reaction between UO22+ and U4+ aqua ions in acidic solution

      István Bányai, Ildikó Farkas and Imre Tóth

      Article first published online: 8 APR 2015 | DOI: 10.1002/mrc.4235

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      We found that 17O enriched UO22+ ions loose the enrichment by adding U4+ into their acidic aqueous solution. The process could be followed by means of quantitative 17O NMR spectroscopy. The detailed kinetic analysis of the 17O isotope exchange resulted in the experimental determination of electron self-exchange between UO22+ and UO2+ ions, in good agreement with earlier estimates and recent quantum chemical calculations. A new acid independent reaction path was identified as well.

    3. Application of 19 F time-domain NMR to measure content in fluorine-containing drug products

      Maria Victoria Silva Elipe, Lan Li, Karthik Nagapudi, Alan M. Kook, Carlos Cobas, Isaac Iglesias and Chen Peng

      Article first published online: 13 MAR 2015 | DOI: 10.1002/mrc.4223

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      The average drug content of three fluorinated drug products, cinacalcet, lansoprazole, and ciprofloxacin, were measured using low field 19 F TD-NMR to compare with the reported label claims (doses ranging from 15 to 500 mg). The data suggest that the technique is suitable for quality control and development work to measure the average amount of drug substance in formulated drugs containing fluorine. TD-NMR is a simple, non-destructive technique and excellent PAT tool for development and manufacturing in the pharmaceutical industry.

    4. Differentiation of enantiomers by 2D NMR spectroscopy at 1 T using residual dipolar couplings

      Martin R. M. Koos, Ernesto Danieli, Federico Casanova, Bernhard Blümich and Burkhard Luy

      Article first published online: 13 MAR 2015 | DOI: 10.1002/mrc.4222

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      Differentiating enantiomers using 2D bench-top NMR spectroscopy. Spectrometers working with permanent magnets at 1 T field strength allow the acquisition of 2D data sets. In conjunction with previously reported chiral alignment media, this setup allows the measurement of enantiomeric excess via residual dipolar couplings in stretched gelatine as a result of the reduced line width obtained by 2D J-resolved spectroscopy.

    5. Monitoring chemical reactions by low-field benchtop NMR at 45 MHz: pros and cons

      Maria Victoria Silva Elipe and Robert R. Milburn

      Article first published online: 23 JAN 2015 | DOI: 10.1002/mrc.4189

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      Chemical reactions were followed by low-field NMR. A 45 MHz benchtop NMR instrument was tested to monitor three types of reactions by 1D 1H NMR: a Fischer esterification, a Suzuki cross-coupling, and the formation of an oxime. Only protonated solvents were used with no observation of lineshape degradation by magnetic drift. Aliquots were injected over time into the NMR flow cell at the temperature of the magnet. A low signal-to-noise ratio of 10 : 1 for the solvent/analyte signals is reasonable.

  25. Special issue rapid communications

    1. Natural abundant 17O NMR in a 1.5-T Halbach magnet

      Morten K. Sørensen, Oleg N. Bakharev, Ole Jensen and Niels Chr. Nielsen

      Article first published online: 16 JAN 2015 | DOI: 10.1002/mrc.4207

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      We present mobile, low-field 17O NMR as a means for monitoring oxygen in liquids. Whereas oxygen is one of the most important elements, oxygen NMR is limited by a poor sensitivity related to low natural abundance and gyro-magnetic ratio of the NMR active 17O isotope. Here, we demonstrate 17O NMR detection at a Larmor frequency of 8.74 MHz in a 1.5-T Halbach neodymium magnet with a home-built digital NMR instrument suitable for large-scale production and in-line monitoring applications.

  26. Special issue mini-reviews

    1. Spatially resolved chemical reaction monitoring using magnetic resonance imaging

      Kirk W. Feindel

      Article first published online: 14 JAN 2015 | DOI: 10.1002/mrc.4179

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      This mini-review provides an update on the recent use of magnetic resonance imaging (MRI) for spatially resolved chemical reaction monitoring. Examples demonstrating the use of 1H, 7Li, 11B, 19F, and 27Al MRI are included.

    2. NMR spectroscopy to follow reaction progress in ionic liquids

      Bradley J. Butler, Donald S. Thomas, James M. Hook and Jason B. Harper

      Article first published online: 7 OCT 2014 | DOI: 10.1002/mrc.4161

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      This review highlights the advantages of NMR spectroscopy over other analytical techniques in following reaction progress in ionic liquids, particularly addressing the practical aspects of the methodology and highlighting the range of processes that can be readily followed.


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