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Magnetic Resonance in Chemistry: MRC

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https://www.readbyqxmd.com/read/27878854/special-issue-bill-reynolds-legacy
#1
EDITORIAL
Roberto R Gil, Gary E Martin
No abstract text is available yet for this article.
November 23, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27859567/structure-and-absolute-configuration-of-hydroxy-bis-dihydrofarinosin-from-encelia-farinosa
#2
Alfredo R Ortega, Naytzé Ortiz-Pastrana, Leovigildo Quijano, Elvia Becerra-Martínez, José O Olmedo-Aguirre, Pedro Joseph-Nathan
The structure of the dimeric eudesmanolide hydroxy-bis-dihydrofarinosin (1) from Encelia farinosa followed after contrasting their (1) H and (13) C NMR spectra with those of encelin (6), hydroxy-bis-dihydroencelin (3), and farinosin (4). Structure 1 was verified by single crystal X-ray diffraction analysis, which further provided the streochemistry of the hydroxy group at C-4. Comparison of the experimental vibrational circular dichroism spectrum of its derived diacetate 2 with that calculated by DFT provided the absolute configuration, which resulted the same as that of its biogenetic precursor 4...
November 16, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27862240/solid-state-nmr-study-on-changes-of-phosphate-and-proton-species-in-metal-pyrophosphate-composite-mp2-o7-mo2-ceramics
#3
Masakazu Nishida, Tomoko Tanaka, Wataru Kanematsu
In order to investigate the effects of composite production and the role of the counter cation for metal phosphate conductors, changes in the solid state NMR spectra and magnetic relaxation times caused by the removal of volatile products and water washing were examined for various metal pyrophosphate (MP2 O7 -MO2 ; M = Sn, Si, Ti, Zr). Acidic species could be detected by (1) H MAS NMR spectra for all the composites except ZrP2 O7 -ZrO2 which had the lowest conductivity. The (31) P DD-MAS NMR spectra for MP2 O7 -MO2 composites showed different signal patterns depending on the counter cations participating in the ion exchange as a result of different microstructures...
November 12, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27859555/pyruvate-cellular-uptake-and-enzymatic-conversion-probed-by-dissolution-dnp-nmr-the-impact-of-overexpressed-membrane-transporters
#4
Riccardo Balzan, Laetitia Fernandes, Laetitia Pidial, Arnaud Comment, Bertrand Tavitian, Paul R Vasos
Pyruvate membrane crossing and its LDH-mediated conversion to lactate in cells featuring different levels of expression of membrane monocarboxylate transporters (MCT4) was probed using dissolution DNP-enhanced NMR. Hyperpolarized (13) C-1 labeled pyruvate was transferred to suspensions of rodent tumor cells CCL39. The pyruvate-to-lactate conversion rate monitored by dissolution-DNP NMR in CCL39 featuring native MCT4 expression level was lower than the rate observed for cells in which the human MCT4 gene was over-expressed...
November 12, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27859547/study-of-spontaneous-e-z-isomerization-of-bis-z-cyanomethylidene-diazapentacyclodienedicarboxylates-by-1-h-13-c-and-15-n-nmr-spectroscopy-x-ray-and-quantum-chemical-calculations-data
#5
Andrei V Afonin, Alexander V Vashchenko, Alexander I Albanov, Valentina V Nosyreva, Anastasiya G Mal'kina, Boris A Trofimov
X-Ray data show that the diethyl 6,13-bis[(Z)-cyanomethylidene]-5,5,14,14-tetramethyl-4,15-dioxa-7,12-diazapentacyclo[9.5.2.0(2,10) .0(3,7) .0(12,16) ]octadeca-8,17-diene-10,17-dicarboxylate is formed as the ZZ isomer and diastereomer with the (1R*,2R*,3R*,10S*,11R*,12R*,16R*) configuration. The (1) H, (13) C and (15) N NMR data exhibit that on standing in chloroform-d solution there is a spontaneous isomerization of this compound resulting in a thermodynamically stable mixture of the ZZ, ZE, EE and EZ isomers with the same backbone...
November 9, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27859693/structural-analysis-of-oleanane-type-saponins-from-the-roots-of-wisteria-frutescens
#6
Anne-Sophie Champy, Anne-Claire Mitaine-Offer, Tomofumi Miyamoto, Chiaki Tanaka, Anna-Maria Papini, Marie-Aleth Lacaille-Dubois
No abstract text is available yet for this article.
November 8, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27921330/the-new-face-of-isotopic-nmr-at-natural-abundance
#7
Tangi Jézéquel, Valentin Joubert, Patrick Giraudeau, Gérald S Remaud, Serge Akoka
The most widely used method for isotope analysis at natural abundance is isotope ratio monitoring by Mass Spectrometry (irm-MS) which provides bulk isotopic composition in (2) H, (13) C, (15) N, (18) O or (34) S. However, in the 1980s, the direct access to Site-specific Natural Isotope Fractionation by Nuclear Magnetic Resonance (SNIF-NMR(TM) ) was immediately recognized as a powerful technique to authenticate the origin of natural or synthetic products. The initial - and still most popular - application consisted in detecting the chaptalization of wines by irm-(2) H NMR...
November 7, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27813168/real-time-band-selective-f1-decoupled-proton-nmr-for-the-demixing-of-overlay-spectra-of-chiral-molecules
#8
Nilamoni Nath, Ajay Verma, Bikash Baishya, Chunni Lal Khetrapal
The small chemical shift dispersion and complex multiplicity pattern in proton NMR limit quantifications, for instance the determination of enantiomeric excess (ee) for an enantiomeric mixture. Herein, we present a simple proton-proton correlation experiment with band selective homonuclear (BASH) decoupling in both F1 and F2 dimensions, for the removal of scalar and residual dipolar couplings to provide collapsed singlet for each chemical site. The method has been demonstrated to separate the severely overlapped spectra of enantiomers using both chiral isotropic and anisotropic phases as well as a small biomolecule, particularly for the diastereotopic protons and also for the determination of ee...
November 3, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27785822/autonomous-driving-in-nmr
#9
Manuel Perez
No abstract text is available yet for this article.
October 27, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27761957/pure-shift-1-h-nmr-what-s-next
#10
Laura Castañar
No abstract text is available yet for this article.
October 19, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27748982/mobile-nmr-an-essential-tool-for-protecting-our-cultural-heritage
#11
Maria Baias
What is "cultural heritage"? Is it simply our legacy of physical artifacts - or is it our collective legacy as human societies - how we want to be remembered by future generations? With time, negligence, and even military conflict working to erase the past, we must ask: Can a better understanding of our shared heritage assist us in addressing cultural differences in the present day? And how can science both help us understand the historic record and work to preserve it? In this perspective article we examine an emerging scientific method, mobile nuclear magnetic resonance, that can help us examine in a non-invasive way important objects and sites of our cultural heritage...
October 17, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27743456/perspectives-in-the-application-of-residual-dipolar-couplings-in-the-structure-elucidation-of-weakly-aligned-small-molecules
#12
Volker Schmidts
This perspective article aims to review the general methodology in the application of residual dipolar couplings (RDCs) in the structure elucidation of small molecules and give the author's view on challenges for future applications. Recent improvements in the availability of alignment media, new pulse sequences for the measurement of couplings and improvements in the analysis software have garnered widespread interest in the technique. However, further generalization is needed in order to make RDC analysis into a truly "routine" method...
October 15, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27743453/perspectives-on-the-future-of-nmr-by-the-associate-editors
#13
EDITORIAL
Patrick Giraudeau, Roberto R Gil
No abstract text is available yet for this article.
October 15, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27737497/isolation-and-characterization-of-roridin-e
#14
Clark D Ridge, Eugene P Mazzola, Martyn P Coles, Simon F R Hinkley
The commonly occurring, high-cytotoxicity macrolide roridin E has been re-isolated from Stachybotrys chartarum and characterized by 1-D and 2-D NMR spectroscopy. Assignment of the spectral data for roridin E revealed differences from the accepted literature, and spectra are reported herein to aid in future identification. For the first time confirmation of structure was provided by a crystallographic solution for roridin E. Copyright © 2016 John Wiley & Sons, Ltd.
October 13, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27733011/structural-elucidation-of-a-series-of-6-methyl-3-carboxamidocoumarins
#15
André Fonseca, Alexandra Gaspar, Maria João Matos, Ligia R Gomes, John N Low, Eugenio Uriarte, Fernanda Borges
No abstract text is available yet for this article.
October 12, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27726201/ultrafast-nmr-diffusion-measurements-exploiting-chirp-spin-echoes
#16
Susanna Ahola, Otto Mankinen, Ville-Veikko Telkki
Standard diffusion NMR measurements require the repetition of the experiment multiple times with varying gradient strength or diffusion delay. This makes the experiment time-consuming and restricts the use of hyperpolarized substances to boost sensitivity. We propose a novel single-scan diffusion experiment, which is based on spatial encoding of two-dimensional data, employing the spin-echoes created by two successive adiabatic frequency-swept chirp π pulses. The experiment is called ultrafast pulsed-field-gradient spin-echo (UF-PGSE)...
October 11, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27718501/progress-toward-reaction-monitoring-at-variable-temperatures-a-new-stopped-flow-nmr-probe-design
#17
Anna L Dunn, Clark R Landis
A stopped-flow NMR probe is described that enables fast flow rates, short transfer times, and equilibration of the reactant magnetization and temperature prior to reaction. The capabilities of the probe are demonstrated by monitoring the polymerization of lactide as catalyzed by the air-sensitive catalyst 1,3-dimesitylimidazol-2-ylidene (IMes) over the temperature range of -30 to 40 °C. The incorporation of stopped-flow capabilities into an NMR probe permits the rich information content of NMR to be accessed during the first few seconds of a fast reaction...
October 8, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27711991/conformational-study-of-tylosin-a-in-water-and-full-assignments-of-1-h-and-13-c-spectra-of-tylosin-a-in-d2-o-and-tylosin-b-in-cdcl3
#18
Biljana Arsic, Juan A Aguilar, Richard A Bryce, Jill Barber
No abstract text is available yet for this article.
October 6, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27706849/assignment-of-oxime-and-hydrazone-configuration-using-1-h-15-n-and-13-c-15-n-coupling-measurements-at-natural-abundance
#19
Mike Kline, Dawn Pierce, Steve Cheatham
Measurement of (1) H-(15) N and (13) C-(15) N coupling constants at natural abundance is demonstrated to be a reliable and generic method to determine the configuration of oximes, hydrazines, and related systems. Data on (1) H-(15) N and (13) C-(15) N coupling constants on a variety of systems obtained at natural abundance confirm the geometric dependence of the measured (1) H-(15) N and (13) C-(15) N coupling constants. In addition, we summarize a simple "decision-tree" for determining configuration based on practical considerations of sample quantity, solubility, and complexity...
October 5, 2016: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/27682239/-1-h-and-13-c-nmr-spectral-assignments-of-flavone-derivatives
#20
Beom Soo Kim, Eun Jee Koh, Yearam Jung, Soon Young Shin, Yoongho Lim
No abstract text is available yet for this article.
September 28, 2016: Magnetic Resonance in Chemistry: MRC
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