2,489 results match your criteria Magnetic Resonance in Chemistry [Journal]


Nuclear Magnetic Relaxation and Diffusion Study of the Ionic Liquids 1-ethyl- and 1-butyl-3-methylimidazolium bis (trifluoromethylsulphonyl)imide Confined in Porous Glass.

Magn Reson Chem 2019 Feb 15. Epub 2019 Feb 15.

Department of Technical Physics II, Institute of Physics, Technische Universität Ilmenau, 98684, Ilmenau, Germany.

The molecular dynamics of the room-temperature ionic liquid 1-butyl-3-methylimidazolium bis (trifluoromethylsulphonyl)imide (Bmim Tf2N) confined in porous glass is studied by NMR relaxometry and diffusometry, and is compared to its bulk dynamics over a wide temperature range. The molecular reorientation processes for anions and cations alike are found to be significantly affected by the presence of the glass interface at high temperatures. In this respect, the ionic liquid behaves similar to polar liquids where proton NMR relaxation is governed by reorientations mediated by translational displacements (RMTD). Read More

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http://dx.doi.org/10.1002/mrc.4852DOI Listing
February 2019

DFT computational schemes for N NMR chemical shifts of the condensed nitrogen containing heterocycles.

Magn Reson Chem 2019 Feb 15. Epub 2019 Feb 15.

A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russian Federation.

A systematic DFT study of the accuracy factors (functionals, basis sets, solvent effects) for the computation of N NMR chemical shifts has been performed in the series of condensed nitrogen containing heterocycles. The behavior of the most representative functionals was examined based on the benchmark calculations of N NMR chemical shifts in the reference set of compounds. It was found that the best agreement with experiment was achieved with OLYP functional in combination with aug-pcS-3(N)//pc-2 locally dense basis set scheme providing MAE of 5. Read More

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http://dx.doi.org/10.1002/mrc.4851DOI Listing
February 2019

Identification of Metabolites in Coriander seeds (Coriandrum Sativum L.) Aided by Ultrahigh Resolution Total Correlation NMR Spectroscopy.

Magn Reson Chem 2019 Feb 14. Epub 2019 Feb 14.

Centre of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, 226014, U.P, INDIA.

NMR is a fast method for obtaining a holistic snapshot of the metabolome and also offers quantitative information without separating the compounds present in a complex mixture. Identification of the metabolites present in a plant extract sample is a crucial step for all plant metabolomics studies. In the present work, we used various two dimensional (2D) NMR methods such as J-Resolved NMR, TOCSY, and HSQC NMR spectroscopy for the identification of thirty-six common metabolites present in Coriandrum sativum L. Read More

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http://dx.doi.org/10.1002/mrc.4850DOI Listing
February 2019

Monitoring Dendrimer Conformational Transition using F and H O NMR.

Magn Reson Chem 2019 Feb 11. Epub 2019 Feb 11.

Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD, 21201, USA.

The conformational transition of a fluorinated amphiphilic dendrimer is monitored by the H signal from water, alongside the F signal from the dendrimer. High-field NMR data (chemical shift δ, self-diffusion coefficient D, longitudinal relaxation rate R , and transverse relaxation rate R ) for both dendrimer ( F) and water ( H) match each other in detecting the conformational transition. Among all parameters for both nuclei, water proton transverse relaxation rate R ( H O) displays the highest relative scale of change upon conformational transition of the dendrimer. Read More

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http://dx.doi.org/10.1002/mrc.4849DOI Listing
February 2019

Reducing the computational cost of NMR crystallography of organic powders at natural isotopic abundance with the help of C- C dipolar couplings.

Magn Reson Chem 2019 Feb 8. Epub 2019 Feb 8.

Aix Marseille Univ, CNRS, ICR, Marseille, France.

Structure determination of functional organic compounds remains a formidable challenge when the sample exists as a powder. NMR crystallography approaches based on the comparison of experimental and DFT-computed 1H chemical shifts have already demonstrated great potential for structure determination of organic powders, but limitations still persist. In this study we discuss the possibility of using 13C-13C dipolar couplings quantified on powdered theophylline at natural isotopic abundance with the help of dynamic nuclear polarisation, to realize a DFT-free, rapid, screening of a pool of structures predicted by AIRSS. Read More

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http://dx.doi.org/10.1002/mrc.4848DOI Listing
February 2019

Phenylpropanoids, flavonoids and terpenoids from Artemisia ordosica Krasch.

Magn Reson Chem 2019 Feb 7. Epub 2019 Feb 7.

College of Traditional Mongolian Medicine, Inner Mongolia University for Nationalities, Tongliao, 028000, Inner Mongolia, China.

From the CH Cl extract of Artemisia ordosica, two new phenylpropanoids, ordosicin A (9) and ordosicin B (10), was obtained in addition to two known phenylpropanoids [dihydroconiferyl alcohol (3) and coniferyl alcohol (4)]. Moreover, five flavonoids [5-hydroxy-7,4'-dimethoxyflavanone (5), 3,5-dihydroxy-7,4'-dimethoxyflavone (6), 5,4'-dihydroxy-7-methoxyflavanone (7), 5,4'-dihydroxy-7,3'-dimethoxyflavanone (8) and acacetin (11)] and two terpenoids [spathulenol (1) and uvaol (2)] were isolated and identified. The structures of new compounds were elucidated on the basis of spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR. Read More

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http://dx.doi.org/10.1002/mrc.4846DOI Listing
February 2019
1 Read

Effect of D-Psicose Substitution on Gelatin Based Soft Candies: A TD-NMR Study.

Magn Reson Chem 2019 Feb 7. Epub 2019 Feb 7.

Department of Food Engineering, Middle East Technical University, Ankara, Turkey.

Confectionary gels are considered as composite gel systems composed of high amount of sugar and gelling agent such as gelatin or starch. D-Psicose is classified as a type of rare sugar which is a C-3 epimer of fructose and has 70% of the sweetness of sucrose with a caloric value of 0.39 kcal/g. Read More

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http://dx.doi.org/10.1002/mrc.4847DOI Listing
February 2019

A preliminary study of milk powder hydration using TEDSpiL continuous wave NMR.

Magn Reson Chem 2019 Feb 1. Epub 2019 Feb 1.

School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.

Moisture content of foodstuffs are typically assessed by Titration or Near Infrared Spectroscopy which are labour intensive as a manual measurement or costly when automated. Magnetic Resonance offers a method for moisture evaluation but is also normally costly. In this work we revisit Look and Locker's "Tone Burst" experiment with a marginal oscillator to evaluate moisture content of powdered skimmed milk subjected to increased humidity. Read More

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http://dx.doi.org/10.1002/mrc.4845DOI Listing
February 2019

Synthesis of α-Fluoro-α,β-unsaturated esters monitored by 1D and 2D benchtop NMR Spectroscopy.

Magn Reson Chem 2019 Jan 31. Epub 2019 Jan 31.

Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, D-52074, Aachen, Germany.

For optimization and control of pharmaceutically and industrially important reactions chemical information is required in real time. Instrument size, handling and operation costs are important criteria to be considered when choosing a suitable analytical method apart from sensitivity and resolution. This present study explores the use of a robust and compact NMR spectrometer to monitor the stereo-selective formation of α-fluoro-α,β-unsaturated esters from α-fluoro-β-keto esters via deprotonation and deacylation in real-time. Read More

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http://dx.doi.org/10.1002/mrc.4843DOI Listing
January 2019

H- C HMBC NMR experiments as a structural and analytical tool for the characterization of elusive trans/cis hydroperoxide isomers from oxidized unsaturated fatty acids in solution.

Magn Reson Chem 2019 Jan 31. Epub 2019 Jan 31.

H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, 75270, Pakistan.

The radical-dependent oxidation of unsaturated fatty acids is a fundamental reaction in lipid chemistry, biochemistry and technology. We report herein the first successful application of H- C HMBC NMR experiment for the identification and quantification of complex and minor (3.9 to 0. Read More

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http://dx.doi.org/10.1002/mrc.4844DOI Listing
January 2019

Determination of the N chemical shift anisotropy in natural abundance samples by proton-detected 3D solid-state NMR under ultrafast MAS of 70 kHz.

Magn Reson Chem 2019 Jan 26. Epub 2019 Jan 26.

RIKEN-JEOL Collaboration Center, Yokohama, Kanagawa, Japan.

Chemical shift anisotropy (CSA) is a sensitive probe of electronic environment at a nucleus, and thus, it offers deeper insights into detailed structural and dynamic properties of different systems, for example, chemical, biological, and materials. Over the years, massive efforts have been made to develop recoupling methods that reintroduce CSA interaction under magic angle spinning (MAS) conditions. Most of them require slow or moderate MAS (≤20 kHz) and isotopically enriched samples. Read More

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http://dx.doi.org/10.1002/mrc.4841DOI Listing
January 2019
1 Read

Water and oil signal assignment in low-moisture mozzarella as determined by time-domain NMR T relaxometry.

Magn Reson Chem 2019 Jan 24. Epub 2019 Jan 24.

Particle and Interfacial Technology Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium.

A time-domain H NMR relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional CPMG sequence and a FID-CPMG sequence. Read More

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http://doi.wiley.com/10.1002/mrc.4842
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http://dx.doi.org/10.1002/mrc.4842DOI Listing
January 2019
2 Reads

NMR-based differentiation of conventionally from organically produced chicken eggs in Germany.

Magn Reson Chem 2019 Jan 24. Epub 2019 Jan 24.

Department of Food Chemistry and Phytochemistry Institut, Karlsruhe Institute of Technologie (KIT), Kaiserstr. 12, 76131, Karlsruhe, Germany.

Both the German and European organic food markets are growing fast, and there is also a rising demand for organic chicken eggs. Consumers are willing to pay higher prices for organic eggs produced in an animal appropriate environment considering animal welfare. Strict labelling requirements do not prevent chicken eggs from being a subject of food fraud. Read More

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http://dx.doi.org/10.1002/mrc.4838DOI Listing
January 2019
1 Read

Practical aspects of the simultaneous collection of COSY and TOCSY spectra.

Magn Reson Chem 2019 Jan 24. Epub 2019 Jan 24.

Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Barcelona, Catalonia, Spain.

The practical aspects of some NMR experiments designed for the simultaneous acquisition of 2D COSY and 2D TOCSY spectra are presented and discussed. Several techniques involving afterglow-based, CTP-based and NOAH-based strategies for the collection of different FIDs within the same scan are evaluated and compared. These methods offer a faster recording of these spectra in small-molecule NMR when sensitivity is not a limiting factor, with a reduction in spectrometer time about 45%-60% when compared to the conventional sequential acquisition of the parent experiments. Read More

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http://dx.doi.org/10.1002/mrc.4835DOI Listing
January 2019

H and C NMR reassignment of some chemical shifts of lantanilic acid and camaric acid.

Magn Reson Chem 2019 Jan 24. Epub 2019 Jan 24.

Instituto de Química, Universidad Nacional Autónoma de México. Circuito Exterior s/n, Ciudad Universitaria, 04510, Delegación Coyoacán, CDMX, México.

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http://dx.doi.org/10.1002/mrc.4839DOI Listing
January 2019

Exploring the tumour extracellular matrix by in vivo Fast Field Cycling Relaxometry after the administration of a Gadolinium based MRI contrast agent.

Magn Reson Chem 2019 Jan 24. Epub 2019 Jan 24.

Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.

H Fast-Field Cycling NMR relaxometry is proposed as a powerful method to investigate tumour stroma in vivo upon the administration of a Gd based contrast agent. To perform this study, a FFC-NMR equipment endowed with a wide bore magnet was used for the acquisition of Nuclear Magnetic Resonance Dispersion (NMRD) profiles on healthy muscle and tumour tissue in living mice. At magnetic field strengths < of ca. Read More

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http://doi.wiley.com/10.1002/mrc.4837
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http://dx.doi.org/10.1002/mrc.4837DOI Listing
January 2019
6 Reads

Fat crystals: A tool to inhibit molecular transport in W/O/W double emulsions.

Magn Reson Chem 2019 Jan 22. Epub 2019 Jan 22.

Particle and Interfacial Technology Group, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.

Water-in-oil-in-water (W/O/W) double emulsions are a promising technology for encapsulation applications of water soluble compounds with respect to functional food systems. Yet molecular transport through the oil phase is a well-known problem for liquid oil-based double emulsions. The influence of network crystallization in the oil phase of W/O/W globules was evaluated by NMR and laser light scattering experiments on both a liquid oil-based double emulsion and a solid fat-based double emulsion. Read More

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http://doi.wiley.com/10.1002/mrc.4840
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http://dx.doi.org/10.1002/mrc.4840DOI Listing
January 2019
4 Reads

Regularized inversion of the laplace transform for series of experiments.

Magn Reson Chem 2019 Jan 22. Epub 2019 Jan 22.

Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, Germany.

Not only in Low-Field NMR, Laplace inversion is a relevant and challenging topic. Considerable conceptual and technical progress has been made, especially for the inversion of data encoding two decay dimensions. Distortion of spectra by overfitting of even moderate noise is counteracted requiring a priori smooth spectra. Read More

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http://dx.doi.org/10.1002/mrc.4836DOI Listing
January 2019

Identification of markers of thermal processing ("roasting") in aqueous extracts of Coffea arabica L. seeds through NMR fingerprinting and chemometrics.

Magn Reson Chem 2019 Jan 21. Epub 2019 Jan 21.

UMR 1145, AgroParisTech, Inra, Université Paris-Saclay, 91300, Massy, France.

Roasting of Coffea arabica L. seeds gives rise to chemical reactions that produce more than 800 compounds, some being responsible for the desired organoleptic properties for which the beverage called "coffee" is known. In the industry, the "roasting profile", i. Read More

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http://dx.doi.org/10.1002/mrc.4834DOI Listing
January 2019
1 Read

Full H and C NMR spectral assignment of conjugated valerolactone metabolites isolated from urine of black tea consumers by means of SPE-prepLC-MS-LC-MS-NMR.

Magn Reson Chem 2019 Jan 18. Epub 2019 Jan 18.

Unilever R&D, Vlaardingen, The Netherlands.

The health benefits of black tea have been linked to polyphenol metabolites that target specific modes of action in the human body. A major bottleneck in unravelling the underlying mechanisms is the preparative isolation of these metabolites which hampers their structural elucidation and assessment of in vitro bioactivity. A SPE-prepLC-MS-LC-MS-NMR workflow was implemented for preparative isolation of conjugated valerolactone metabolites of catechin-based polyphenols from urine of black tea consumers. Read More

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http://dx.doi.org/10.1002/mrc.4833DOI Listing
January 2019

Effect of long-term heat exposure on rheological and intrinsic water characteristics of bone-derived beef stocks.

Magn Reson Chem 2019 Jan 15. Epub 2019 Jan 15.

Department of Food Science, Research Centre Aarslev, Aarhus University, Aarslev, Denmark.

Bone-derived protein stocks are used in food industry to enhance taste of soups, sauces, and a range of other products. Both during commercial manufacturing and when used for culinary purposes, the stocks may be exposed to high temperatures for an extended time period. The present study investigated the effect of retention at 90°C for 0, 3, 6, 9, 24, 48, 72, and 168 hr on the functional attributes of concentrated bone-derived beef stocks (57% Dry matter (DM)). Read More

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http://dx.doi.org/10.1002/mrc.4831DOI Listing
January 2019
1 Read

QSAR studies of phenylhydrazine-substituted tetronic acid derivatives based on the H NMR and C NMR chemical shifts.

Magn Reson Chem 2019 Jan 11. Epub 2019 Jan 11.

Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing, China.

The quantitative structure-activity relationship models of 40 phenylhydrazine-substituted tetronic acid derivatives were established between the H nuclear magnetic resonance (NMR) and C NMR chemical shifts and the antifungal activity against Fusarium graminearum, Botrytis cinerea, Rhizoctonia cerealis, and Colletotrichum capsici. The models were validated by R, R , R , variance inflation factor, F, and P values testing and residual analysis. It was concluded from the models that the C NMR chemical shifts of C8, C10, C7, and the H NMR chemical shifts of Ha contributed positively to the activity against Fusarium graminearum, Botrytis cinerea, Colletotrichum capsici, and Rhizoctonia cerealis, respectively. Read More

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http://dx.doi.org/10.1002/mrc.4830DOI Listing
January 2019
5 Reads

Characterization of gluten-free bread crumb baked at atmospheric and reduced pressures using TD-NMR.

Magn Reson Chem 2019 Jan 8. Epub 2019 Jan 8.

Irstea, OPAALE, IRM Food team, Rennes, France.

This research aimed to study the effects of using a partial vacuum for bread baking on macromolecules and water distribution in gluten-free bread. Bread baking under partial vacuum results in greater oven rise and a larger gas fraction in the crumb. Because water's boiling point decreases under reduced pressure, it was expected that its distribution within the dough and its interactions with the others dough's constituents (mainly starch) would differ from those in bread baked under atmospheric pressure. Read More

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http://dx.doi.org/10.1002/mrc.4829DOI Listing
January 2019
1 Read

Calculations of C NMR chemical shifts and F-C coupling constants of ciprofloxacin.

Magn Reson Chem 2019 Jan 3. Epub 2019 Jan 3.

Institute of Chemistry, Faculty of Natural Sciences and Mathematics, University "Ss. Cyril and Methodius", Skopje, Republic of Macedonia.

Ciprofloxacin is a widely used fluoroquinolone antibiotic. In this work, a comprehensive evaluation of MP2 and DFT with different functionals and basis sets was carried out to select the most suitable level of theory for the study of the NMR properties of ciprofloxacin. Their relative predictive capabilities were evaluated comparing the theoretically predicted and experimental spectral data. Read More

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http://dx.doi.org/10.1002/mrc.4827DOI Listing
January 2019

In situ measurement of deposit layer formation during skim milk filtration by MRI.

Magn Reson Chem 2019 Jan 3. Epub 2019 Jan 3.

Karlsruhe Institute of Technology (KIT), Institute of Mechanical Process Engineering and Mechanics, Karlsruhe, Germany.

Filtration and separation via membranes are key processes in food processing. One major application of membrane filtration is in the dairy industry, aiming for the separation of different milk proteins. The various chemical components of milk possess different physiochemical properties and can be used most effectively in food processing if they are separately available and remain in their native state. Read More

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http://dx.doi.org/10.1002/mrc.4826DOI Listing
January 2019

Application of proton field-cycling NMR relaxometry for studying translational diffusion in simple liquids and polymer melts.

Magn Reson Chem 2019 Jan 2. Epub 2019 Jan 2.

Experimentalphysik and Nordbayerisches NMR-Zentrum, Universität Bayreuth, Bayreuth, Germany.

With the availability of commercial field-cycling relaxometers together with progress of home-built instruments nuclear magnetic resonance relaxometry has gained new momentum as a method of investigating the dynamics in viscous liquids and polymer melts. The method provides the frequency dependence of the spin-lattice relaxation rate. In the case of protons, one distinguishes intramolecular and intermolecular relaxation pathways. Read More

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http://dx.doi.org/10.1002/mrc.4823DOI Listing
January 2019

A theoretical NMR study of polymorphism in crystal structures of azoles and benzazoles.

Magn Reson Chem 2019 Jan 2. Epub 2019 Jan 2.

Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva, 3, Madrid, E-28006, Spain.

The NMR chemical shifts of two azoles and one benzazole whose crystal structures present polymorphism have been computed using the GIPAW approach. N and C nuclei have been studied. Statistical analysis of the computed C and N chemical shifts indicates that the GIPAW chemical shifts reproduce with a high degree of accuracy those experimentally reported. Read More

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http://dx.doi.org/10.1002/mrc.4824DOI Listing
January 2019

Benchtop NMR for the monitoring of bioprocesses.

Magn Reson Chem 2018 Dec 26. Epub 2018 Dec 26.

Université de Nantes, CEISAM, UMR CNRS 6230, Nantes Cedex 3, France.

This mini-review highlights the potential of benchtop nuclear magnetic resonance (NMR) for the monitoring of bioprocesses. It describes recent perspectives opened by the reduced size of devices in relaxometry, magnetic resonance imaging and NMR spectroscopy. In particular, the recent emergence of the benchtop NMR spectroscopy gives access to many applications thanks to the implementation of advanced experiments. Read More

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http://dx.doi.org/10.1002/mrc.4821DOI Listing
December 2018
2 Reads

1,2,3-propanetriol radicals formed during oxidative stress.

Magn Reson Chem 2018 Dec 26. Epub 2018 Dec 26.

Institute of Soil Science and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland.

The presented results attempt to approximate the proper structure of the radical formed as a result of the oxidation of 1,2,3-propanetriol. To fulfil the aim unstable radical originated in 1,2,3-propanetriol was trapped by PBN. Resulted spin adduct was measured using EPR spectroscopy and the isotropic hyperfine coupling constants a ( N) and a ( H) were obtained by simulation of the EPR spectrum. Read More

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http://dx.doi.org/10.1002/mrc.4822DOI Listing
December 2018
1 Read

Toward the comprehensive calculations on the relationship between H, C, P chemical shifts, J , and the bonding structure of different phosphoryl benzamides.

Magn Reson Chem 2018 Dec 22. Epub 2018 Dec 22.

Department of Chemistry, Faculty of Science, Tarbiat Modares University, Tehran, Iran.

A comprehensive investigation was performed on H, C, and P nuclear magnetic resonance (NMR) chemical shifts (CSs) of phosphoryl benzamide derivatives (C H C(O)NHP(O)R R ), (R , R  = aziridine [L ], azetidine [L ], pyrrolidine [L ], piperidine [L ], azepane [L ], 4-methylpiperidine [L ], propane-2-amine [L ], and 2-methylpropane-2-amine [L ]) by the gauge-independent atomic orbital method (GIAO) to find the most accordant level of theory with the experimental values. To achieve this goal, all the structures were optimized using the B3LYP, BP86, PBE1PBE, M06-2X, MPWB1K, and MP2 methods with 6-31+G* basis set. Computed structural parameters demonstrate that BP86 has the best agreement to the experimental values between the other methods. Read More

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http://dx.doi.org/10.1002/mrc.4820DOI Listing
December 2018

Surface influence on the rotational and translational dynamics of molecules confined inside a mesoporous carbon xerogel.

Magn Reson Chem 2018 Dec 21. Epub 2018 Dec 21.

Department of Physics and Chemistry, Technical University of Cluj-Napoca, Cluj-Napoca, Romania.

Low-field nuclear magnetic resonance techniques are employed to extract information about the effects introduced by the interaction with the surface on the rotational and translational dynamics of molecules confined inside a mesoporous carbon xerogel. The molecules under study were water, cyclohexane, and hexane. They were chosen due to their different interaction strength with the carbonaceous matrix. Read More

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http://dx.doi.org/10.1002/mrc.4819DOI Listing
December 2018

Computation and structural elucidation of compounds formed via epoxide alcoholysis.

Magn Reson Chem 2018 Dec 21. Epub 2018 Dec 21.

Department of Chemistry, Universidade Federal de Viçosa, Viçosa, Brazil.

Isobenzofuranones are known for their wide range of biological activities such as fungicide, insecticide, and anticancer. The search for novel bioactive compounds was performed by reaction of epoxide 2 with methanol, ethanol, propan-1-ol, propan-2-ol, and butan-1-ol. The mechanism for the stereoselective and stereospecific epoxide opening with methanol was reasoned by calculating the transition states for the two putative structures (rac)-3a and (rac)-3b. Read More

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http://doi.wiley.com/10.1002/mrc.4818
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http://dx.doi.org/10.1002/mrc.4818DOI Listing
December 2018
5 Reads

Assignment of H and C NMR data for iridoid glycoside derivatives.

Magn Reson Chem 2018 Dec 21. Epub 2018 Dec 21.

U.S. Department of Agriculture, Food Composition and Methods Development Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, Beltsville, MD, USA.

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http://dx.doi.org/10.1002/mrc.4817DOI Listing
December 2018
1 Read

Practical application of H benchtop NMR spectroscopy for the characterization of a nonaqueous phase liquid from a contaminated environment.

Magn Reson Chem 2018 Dec 17. Epub 2018 Dec 17.

School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada.

Nonaqueous phase liquids (NAPLs) located at the surface of the water table and/or below the water table are often a significant source for groundwater contamination near current or former commercial/industrial facilities. Due to the complex and long history of many industrial sites, these NAPLs often contain a complex mixture of contaminants and as such can be difficult to fully characterize using conventional analytical methods. Remediation and risk assessment activities at sites containing NAPLs may, subsequently, be hindered as the contamination profile may not be fully understood. Read More

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http://dx.doi.org/10.1002/mrc.4816DOI Listing
December 2018
2 Reads

Quantification of the electrostatic and covalent interaction between whey proteins and low methoxyl pectin using PFG-NMR diffusometry.

Magn Reson Chem 2018 Dec 10. Epub 2018 Dec 10.

Particle and Interfacial Technology Group, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.

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http://doi.wiley.com/10.1002/mrc.4812
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http://dx.doi.org/10.1002/mrc.4812DOI Listing
December 2018
3 Reads

Improvements in lipid suppression for H NMR-based metabolomics: Applications to solution-state and HR-MAS NMR in natural and in vivo samples.

Magn Reson Chem 2018 Dec 5. Epub 2018 Dec 5.

Environmental NMR Centre, Department of Physical and Environmental Sciences, University of Toronto, Toronto, Ontario, Canada.

Proton nuclear magnetic resonance (NMR) spectra of intact biological samples often show strong contributions from lipids, which overlap with signals of interest from small metabolites. Pioneering work by Diserens et al. demonstrated that the relative differences in diffusivity and relaxation of lipids versus small metabolites could be exploited to suppress lipid signals, in high-resolution magic angle spinning (HR-MAS) NMR spectroscopy. Read More

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http://doi.wiley.com/10.1002/mrc.4814
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http://dx.doi.org/10.1002/mrc.4814DOI Listing
December 2018
18 Reads

Theoretical investigation on the optical and EPR spectra for Cu -doped ZnO-CdS nanocomposites.

Magn Reson Chem 2018 Dec 5. Epub 2018 Dec 5.

Jiangxi Engineering Laboratory for Optoelectronics Testing Technology, Nanchang Hangkong University, Nanchang, China.

The three optical absorption bands and EPR parameters of the [CuO ] center in the ZnO-CdS composite nanopowders are theoretically studied from the perturbation formulas based on the cluster approach. In the formulas, the contributions to EPR parameters arising from the ligand orbital and spin-orbit coupling interactions via covalence effect are considered. For the studied [CuO ] cluster, the Cu-O bond lengths are suggested to show a relative elongation ratio ρ (≈ 4. Read More

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http://doi.wiley.com/10.1002/mrc.4813
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http://dx.doi.org/10.1002/mrc.4813DOI Listing
December 2018
10 Reads

Selective oil-phase rheo-MRI velocity profiles to monitor heterogeneous flow behavior of oil/water food emulsions.

Magn Reson Chem 2018 Dec 4. Epub 2018 Dec 4.

Laboratory of Biophysics, Wageningen University and Research, Wageningen, The Netherlands.

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http://dx.doi.org/10.1002/mrc.4811DOI Listing
December 2018

D-HMBC versus LR-HSQMBC: Which experiment provides theoretically and experimentally the best results?

Magn Reson Chem 2018 Nov 29. Epub 2018 Nov 29.

Departement für Chemie und Biochemie, Universität Bern, Bern, Switzerland.

The long-range heteronuclear single quantum multiple bond correlation (LR-HSQMBC) experiment is the experiment of choice for visualizing heteronuclear long-range coupling interactions J 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 J -dedicated investigation to the D-HMBC and LR-HSQMBC experiments. Read More

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http://dx.doi.org/10.1002/mrc.4810DOI Listing
November 2018

Hydrogen bonding networks in gabapentin protic pharmaceutical salts: NMR and in silico studies.

Magn Reson Chem 2018 Nov 26. Epub 2018 Nov 26.

CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Aveiro, Portugal.

Hydrogen bonds (HBs) play a key role in the supramolecular arrangement of crystalline solids and, although they have been extensively studied, the influence of their strength and geometry on crystal packing remains poorly understood. Here we describe the crystal structures of two novel protic gabapentin (GBP) pharmaceutical salts prepared with the coformers methanesulfonic acid (GBP:METHA) and ethanesulfonic acid (GBP:ETHA). This study encompasses experimental and computational electronic structure analyses of H NMR chemical shifts (CSs), upon in silico HB cleavage. Read More

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http://dx.doi.org/10.1002/mrc.4809DOI Listing
November 2018

P NMR assessment of the phosvitin-iron complex in mayonnaise.

Magn Reson Chem 2018 Nov 25. Epub 2018 Nov 25.

Spectroscopy & Imaging, Unilever Research and Development Vlaardingen, Vlaardingen, the Netherlands.

Lipid oxidation is the main reason for the limited shelf life of mayonnaise. One of the main catalysts of this process is iron, which is introduced in its ferric (Fe(III)) form via phosvitin, an egg yolk phosphoprotein rich in phosphoserines. The binding of Fe(III) to phosvitin and its ability to establish a redox couple with Fe(II) is believed to determine the oxidation rate of unsaturated lipids. Read More

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http://doi.wiley.com/10.1002/mrc.4808
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http://dx.doi.org/10.1002/mrc.4808DOI Listing
November 2018
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Investigation of structure and dynamics in a photochromic molecular crystal by NMR crystallography.

Magn Reson Chem 2018 Nov 19. Epub 2018 Nov 19.

Department of Chemistry, Lancaster University, Lancaster, UK.

A photochromic anil, N-(3,5-di-t-butylsalicylidene)-4-amino-pyridine, has been studied by single-crystal X-ray diffraction, multinuclear magic-angle spinning NMR, and first-principles density functional theory (DFT) calculations. Interpretation of the solid-state NMR data on the basis of calculated chemical shifts confirms the structure is primarily composed of molecules in the ground-state enol tautomer, whereas thermally activated cis-keto and photoisomerised trans-keto states exist as low-level defects with populations that are too low to detect experimentally. Variable temperature C NMR data reveal evidence for solid-state dynamics, which is found to be associated with fast rotational motion of t-butyl groups and 180° flips of the pyridine ring, contrasting the time-averaged structure obtained by X-ray diffraction. Read More

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http://dx.doi.org/10.1002/mrc.4805DOI Listing
November 2018
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The potentiality of NMR-based metabolomics in food science and food authentication assessment.

Magn Reson Chem 2018 Nov 17. Epub 2018 Nov 17.

National Research Council, Institute for Macromolecular Studies (ISMAC), Lab. NMR, v. Corti 12, Milan, 20133, Italy.

In the last years, there was an increasing interest on nuclear magnetic resonance (NMR) spectroscopy, whose applications experienced an exponential growth in several research fields, particularly in food science. NMR was initially developed as the elective technique for structure elucidation of single molecules and nowadays is playing a dominant role in complex mixtures investigations. In the era of the "omics" techniques, NMR was rapidly enrolled as one of the most powerful methods to approach metabolomics studies. Read More

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http://dx.doi.org/10.1002/mrc.4807DOI Listing
November 2018
1 Read

Enhancing signal-to-noise ratio and resolution in low-field NMR relaxation measurements using post-acquisition digital filters.

Magn Reson Chem 2018 Nov 16. Epub 2018 Nov 16.

Embrapa Instrumentação, São Carlos, Brazil.

The traditional way to enhance signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) signals is to increase the number of scans. However, this procedure increases the measuring time that can be prohibitive for some applications. Therefore, we have tested the use of several post-acquisition digital filters to enhance SNR up to one order of magnitude in time domain NMR (TD-NMR) relaxation measurements. Read More

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http://dx.doi.org/10.1002/mrc.4806DOI Listing
November 2018

Chemical shift assignment of mono- and di-bromo triimidazo[1,2-a:1',2'-c:1″,2″-e][1,3,5]triazine derivatives by DFT/NMR integrated approach.

Magn Reson Chem 2018 Nov 13. Epub 2018 Nov 13.

Department of Pharmacy, University of Salerno, Fisciano (SA), Italy.

Mono- and di-bromo derivatives of triimidazo[1,2-a:1',2'-c:1″,2″-e][1,3,5]triazine have been proposed as new organic molecules presenting a very rich and complex photophysical behavior. Thus, we afforded the correct chemical shift assignment by integrating the experimental data with DFT calculation of NMR parameters. Our findings lay foundation for a structural reference in the organic synthesis and characterization of new congeners of this intriguing class of molecules. Read More

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http://dx.doi.org/10.1002/mrc.4804DOI Listing
November 2018
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Dihydro-β-agarofurans from the Australian rainforest plant Denhamia celastroides that inhibit leucine transport in prostate cancer cells.

Magn Reson Chem 2018 Oct 22. Epub 2018 Oct 22.

Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia.

Four new dihydro-β-agarofurans, denhaminols K-N (4-7), along with three known secondary metabolites, denhaminols A-C (1-3) were obtained from the large-scale isolation studies of the leaves of the Australian endemic rainforest plant, Denhamia celastroides. The structures of the previously undescribed compounds were determined by detailed 1D and 2D nuclear magnetic resonance spectroscopy, mass spectrometry, ultraviolet, and infrared data analysis. All compounds were found to inhibit the activity of leucine transport in a human prostate cancer cell line with IC values ranging from 5. Read More

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http://dx.doi.org/10.1002/mrc.4801DOI Listing
October 2018
1.180 Impact Factor

Solid-state NMR tools for the structural characterization of POSiSils: Si sensitivity improvement with MC-CP and 2D Si- Si DQ-SQ at natural abundance.

Magn Reson Chem 2018 Oct 16. Epub 2018 Oct 16.

MIM, Institut Lavoisier de Versailles (ILV), CNRS UMR8180, Université de Versailles Saint-Quentin en Yvelines (UVSQ), Versailles, France.

The H- Si multiple-contact cross polarization (MC-CP) MAS NMR experiment is evaluated for the class of silicate-siloxane copolymers called POSiSils, that is, polyoligosiloxysilicones. It proves a reasonably good solution to tackle the challenge of recording quantitative Si NMR data in experimental time much reduced compared with single pulse acquisition. In a second time, we report Si- Si MC-CP double-quantum single-quantum (MC-CP-DQ-SQ) NMR experiment, which provides information about the through-space proximities between all silicon species despite the high degree of heterogeneity of this material. Read More

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http://dx.doi.org/10.1002/mrc.4800DOI Listing
October 2018
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Solution dynamics of 5-fluorouracil entrapped in poly lactic-co-glycolic acid (PLGA) microsphere-A study with 1D selective NMR methods.

Magn Reson Chem 2018 Oct 10. Epub 2018 Oct 10.

Department of Chemistry, Indian Institute of Technology Jodhpur, Karwar, India.

In this report, our main focus is to introduce a set of one-dimensional (1D) NMR methods based on chemical shift, relaxation, and magnetization transfer, namely, NOE and chemical exchange involving selective pulse excitation to study the solution dynamics of drug in free and encapsulated state within polymeric microsphere. In this regard 5-fluorouracil (5-FU) loaded poly lactic-co-glycolic acid (PLGA) microspheres are prepared as model system via standard water-in-oil-in-water emulsification method. One-dimensional H and F nuclear magnetic resonance (NMR) spectra of 5-FU in presence of PLGA microspheres presented a significant change in linewidth and relaxation rates compared with free 5-FU confirming encapsulation. Read More

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http://doi.wiley.com/10.1002/mrc.4799
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http://dx.doi.org/10.1002/mrc.4799DOI Listing
October 2018
2 Reads

Monitoring daily routine performance in quantitative NMR (qNMR) spectroscopy: Is the system suitability test necessary?

Magn Reson Chem 2018 Oct 2. Epub 2018 Oct 2.

NMR, Spectral Service AG, Köln, Germany.

Nuclear magnetic resonance spectrometry (NMR) finds numerous applications in pharmacy, cosmetic, and food control as well as in developing tools for "big data" analysis. However, there remains a need for automated tools to assess instrument system suitability in real time for each particular routine sample. An automated procedure has been introduced to monitor a number of characteristics (resolution, symmetry, and half width) in real time after the measurement of two samples distributed by the vendor (0. Read More

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http://doi.wiley.com/10.1002/mrc.4798
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http://dx.doi.org/10.1002/mrc.4798DOI Listing
October 2018
11 Reads

Structural studies of calcium channel blockers used in the treatment of hypertension - H and C NMR characteristics of nifedipine analogues.

Magn Reson Chem 2018 Sep 26. Epub 2018 Sep 26.

Department of Physical Chemistry, Chair and Department of Physical Pharmacy and Bioanalysis, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw, Banacha 1, 02-093, Warsaw, Poland.

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http://doi.wiley.com/10.1002/mrc.4797
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http://dx.doi.org/10.1002/mrc.4797DOI Listing
September 2018
16 Reads