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Magnetic Resonance in Chemistry: MRC

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https://www.readbyqxmd.com/read/29127740/molecular-mobility-in-several-imidazolium-based-ionic-liquids-according-to-data-of-1-h-and-13-c-nmr-relaxation
#1
Vladimir V Matveev, Denis A Markelov, Alexandr V Ievlev, Ekaterina A Brui, Konstantin V Tyutyukin, Erkki Lähderanta
Temperature dependences are compared for (1) H and (13) C NMR 1/T1 curves relaxation rates in three imidazolium-based ionic liquids (ILs) namely, in [bmim]PF6 , [bmim]BF4 , and [emim]CH3 COO. (13) C curves show alike behavior for all three ILs and follow a well-known Bloembergen-Pound-Purcell (BPP) equation. On the contrary, an essential part of (1) H curves differ strongly from corresponding (13) C ones and also have different shapes for different ILs. For the first time we have detected the specific, two-maximum shape of (1) H relaxation curve for hydrogen atom of C(2)H group of the [emim]CH3 COO...
November 11, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29127733/-99-tc-nmr-determination-of-the-oxygen-isotope-content-in-18-o-enriched-water
#2
Valerii P Tarasov, Gayana А Kirakosyan, Konstantin E German
(99) Tc NMR has been suggested as an original method of evaluating the content of oxygen isotopes in oxygen-18 enriched water, a precursor for the production of radioisotope fluorine-18 used in positron emission tomography. To this end, solutions of NH4 TcO4 or NaTcO4 (up to 0.28 mol/L) with natural abundance of oxygen isotopes in virgin or recycled (18) O-enriched water have been studied by (99) Tc NMR. The method is based on (16) O/(17) O/(18) O intrinsic isotope effects in the (99) Tc NMR chemical shifts and the statistical distribution of oxygen isotopes in the coordination sphere of TcO4(-) and makes it possible to quantify the composition of enriched water by measuring the relative intensities of the (99) Tc NMR signals of the Tc(16) O4 - n(18) On(-) isotopologues...
November 11, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29117625/nmr-mp2-and-dft-study-of-thiophenoxyketenimines-o-thioschiff-bases-determination-of-the-preferred-form
#3
Bahjat A Saeed, Rita S Elias, Fadhil S Kamounah, Poul Erik Hansen
Five new thiophenoxyketinimines have been synthesized. (1) H and (13) C NMR spectra as well as deuterium isotope effects on (13) C chemical shifts are determined and spectra are assigned. DFT and MP2 calculations of both structures, chemical shifts and isotope effects on chemical shifts are done. The combined analysis reveals that the compounds are primarily on a zwitter ionic form with an NH(+) and a S(-) group and with a little of the neutral form mixed in. Very strong intramolecular hydrogen bonding is found and very high NH chemical shifts are observed...
November 8, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29117453/data-handling-in-nmr-facilities-and-assignment-of-nmr-spectra-in-synthetic-chemistry-labs-why-electronic-structure-validation-should-become-part-of-the-routine
#4
Johannes C Liermann, Nils E Schlörer
No abstract text is available yet for this article.
November 8, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29096425/two-new-isomeric-tricycloalternarenes-from-the-marine-alga-epiphytic-fungus-alternaria-alternata-k23-3
#5
LETTER
Zhen-Zhen Shi, Xiu-Li Yin, Sheng-Tao Fang, Feng-Ping Miao, Nai-Yun Ji
No abstract text is available yet for this article.
November 2, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29077221/a-theoretical-nmr-study-of-selected-benzazoles-comparison-of-gipaw-and-giao-pcm-dmso-calculations
#6
Marta Marín-Luna, Ibon Alkorta, José Elguero
This paper compares the absolute shieldings obtained by GIPAW to those obtained by GIAO/B3LYP/6-311++G(d,p)-PCM (DMSO) for nine benzazoles (benzimidazoles, indazoles, benzotriazoles) recorded in the solid-state. Three nuclei were explored, 13C, 15N and 19F, and the GIPAW approach only proved better for 15N MAS NMR.
October 27, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29049871/a-table-top-pxi-based-low-field-spectrometer-for-solution-dynamic-nuclear-polarization
#7
Joshua R Biller, Karl F Stupic, J Moreland
We present the development of a portable dynamic nuclear polarization (DNP) instrument based on the PCI eXtensions for Instrumentation (PXI) platform. The main purpose of the instrument is for study of (1) H polarization enhancements in solution through the Overhauser mechanism at low magnetic fields. A DNP probe set was constructed for use at 6.7 mT, using a modified Alderman-Grant (MAG) resonator at 241 MHz for saturation of the electron transition. The solenoid for detection of the enhanced (1) H signal at 288 kHz was constructed with Litz wire...
October 19, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29049867/ion-pair-and-solvation-dynamics-of-bmim-bf4-water-system
#8
João Cascão, Wagner Silva, Ana S D Ferreira, Eurico J Cabrita
In this work, [Bmim][BF4 ]/water mixtures were analysed over the whole water composition (xw ) in order to study the rotational and translational behaviour of the ions. We employed a multinuclear NMR approach to determine anion/cation/water diffusion coefficients and longitudinal relaxation rates at different water content. In neat IL the cation diffuses faster than the anion and at low xw anions and cations share almost the same diffusion coefficient, but above a critical water concentration the anion begins to diffuse faster than the cation...
October 19, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29044688/nmr-of-ionic-liquids
#9
EDITORIAL
Krishnan Damodaran
No abstract text is available yet for this article.
October 16, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29044629/clean-pure-shift-2d-j-resolved-spectroscopy
#10
Davy Sinnaeve
2D J-resolved spectroscopy is one of the oldest and conceptually most elegant ways to separate homonuclear scalar couplings from chemical shift information. In practice, the classical experiment suffers from a number of complications that limits accuracy and resolution, including phasetwist lineshapes, strong coupling artifacts, and the need for shearing the spectrum by 45° to obtain a (J,δ)-representation. Here, a novel pure shift 2DJ experiment based on the TSE-PSYCHE experiment is reported that deals with all these issues...
October 16, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28981966/the-c6h6-nmr-repository-an-integral-solution-to-control-the-flow-of-your-data-from-the-magnet-to-the-public
#11
Luc Patiny, Michaël Zasso, Daniel Kostro, Andrés Bernal, Andrés M Castillo, Alejandro Bolaños, Miguel A Asencio, Norman Pellet, Matthew Todd, Nils Schloerer, Stefan Kuhn, Elaine Holmes, Sacha Javor, Julien Wist
NMR is a mature technique that is well established and adopted in a wide range of research facilities from laboratories to hospitals. This accounts for large amounts of valuable experimental data that may be readily exported into a standard and open format. Yet the publication of these data faces an important issue: raw data are not made available; instead, the information is slimed down into a string of characters (the list of peaks). Although historical limitations of technology explain this practice, it is not acceptable in the era of internet...
October 5, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28960443/spin-lattice-relaxation-studies-on-deep-eutectic-solvent-choliniumtetrachloroferrate-mixtures-suitability-of-des-based-systems-towards-magnetic-resonance-imaging-studies
#12
Abhilash Chandra, Prabhat Kumar Sahu, Subhayan Chakraborty, Arindam Ghosh, Moloy Sarkar
This study has been undertaken with an aim to investigate the suitability of the deep eutectic solvents (DES)-based systems for magnetic resonance imaging studies. DESs are used to develop the systems, keeping in mind the fact that these are relatively less toxic than ionic liquids, and hence, DES based magnetic compound is expected to be relatively less toxic than magnetic ionic liquids. In this work, spin-lattice (T1 ) relaxation measurements are carried out in the binary mixtures of deep eutectic solvent with a paramagnetic component choliniumtetrachloroferrate ([Ch][FeCl4 ])...
September 28, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28950409/mspin-jcoupling-a-modular-program-for-prediction-of-scalar-couplings-and-fast-implementation-of-karplus-relationships
#13
Armando Navarro-Vázquez, Raquel Santamaría-Fernández, Francisco Javier Sardina
MSpin-JCoupling is a modular program for the prediction of scalar couplings using a large variety of Karplus relationships. The program was specially designed for small molecule analysis and can be run in graphical or command-line mode. The architecture of the program is highly modular and new equations can be rapidly implemented, through a complete C++ programming interface, and deployed as run-time loadable plugins.
September 26, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28921712/a-review-of-nmr-methods-used-in-the-study-of-the-structure-and-dynamics-of-ionic-liquids
#14
Raju Nanda, Krishnan Damodaran
Recently, NMR spectroscopy has been emerging out as a powerful tool to study the structure and dynamics of ionic liquids (ILs) and ILs-Li(+) salt mixtures. This mini-review primarily focuses on the applications of various NMR spectroscopic techniques such as self-diffusion measurements, NMR relaxometry, two-dimensional NMR and other novel NMR approaches to study the structure and dynamics of ILs and its mixtures with lithium salts.
September 18, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28921691/quantitative-determination-and-validation-of-octreotide-acetate-using-1-h-nmr-spectroscopy-with-internal-standard-method
#15
Chen Yu, Qian Zhang, Peng-Yao Xu, Yin Bai, Wen-Bin Shen, Bin Di, Meng-Xiang Su
Quantitative nuclear magnetic resonance (qNMR) is a well-established technique in quantitative analysis. We presented a validated (1) H quantitative nuclear magnetic resonance ((1) H-qNMR) method for assay of octreotide acetate (OCT-Ac), a kind of cyclic octopeptide. Deuterium oxide was used to remove the undesired exchangeable peaks, which was referred to as proton exchange, in order to make the quantitative signals isolated in the crowded spectrum of the peptide and ensure precise quantitative analysis. Gemcitabine hydrochloride was chosen as the suitable internal standard (IS)...
September 15, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28913938/application-of-craft-complete-reduction-to-amplitude-frequency-table-in-nonuniformly-sampled-nus-2d-nmr-data-processing
#16
Krish Krishnamurthy, Natarajan Hari
The recently published CRAFT (complete reduction to amplitude frequency table) technique converts the raw FID data (i.e., time domain data) into a table of frequencies, amplitudes, decay rate constants, and phases. It offers an alternate approach to decimate time-domain data, with minimal preprocessing step. It has been shown that application of CRAFT technique to process the t1 dimension of the 2D data significantly improved the detectable resolution by its ability to analyze without the use of ubiquitous apodization of extensively zero-filled data...
September 15, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28879664/fast-simulations-of-multidimensional-nmr-spectra-of-proteins-and-peptides
#17
Thomas Vosegaard
To simulate full multidimensional nuclear magnetic resonance spectra of peptides and proteins in a reasonable time frame, a strategy for separating the time-consuming full-density matrix calculations from the chemical shift prediction and calculation of coupling patterns is presented. The simulation setup uses SIMulation Program for SOlid-state NMR (SIMPSON) to calculate total correlation spectroscopy transfer amplitudes and average distances as a source for nuclear Overhauser effect spectroscopy transfer amplitudes...
September 6, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28876470/structure-elucidation-of-new-fusarielins-from-fusarium-sp-and-their-antimicrobial-activity
#18
Abdou Tchoukoua, Ryosuke Hasegawa, Kurniawan Andreas Hendracipta, Satoru Sato, Takuya Koseki, Yoshihito Shiono
Three new fusarielins, 3-epi-fusarielin H (1), 3-O-methyl-fusarielin H (2) and 3-O-methyl-epi-fusarielin H (3), were isolated from the fungus Fusarium sp. together with the known analogues, fusarielins F (4) and G (5). The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. The new compounds exhibited weak antibacterial effect against Staphylococcus aureus.
September 6, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28875542/analysis-on-the-local-structures-for-3d-1-impurities-ti-3-and-v-4-in-ktipo4
#19
C C Ding, S Y Wu, L J Zhang, Y Q Xu, Z H Zhang, M H Wu, B H Teng
Making use of the perturbation formulae for 3d(1) ions (Ti(3+) and V(4+) ) under orthorhombically compressed octahedra, the spin Hamiltonian parameters (SHPs) (g factors: gx , gy , gz and hyperfine structure constants: Ax , Ay , Az ) and local structures of the 3d(1) impurity centres C1 , C2 and C3 in KTP crystals are theoretically analyzed in a consistent way. The remarkable local distortions (i.e., the relative axial compression ratios 11.2%, 7.0% and 5.5% along Z axis and the relative planar bond length variation ratios 15...
September 6, 2017: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/28873503/large-scale-nmr-simulations-in-liquid-state-a-tutorial
#20
Ilya Kuprov
Liquid state NMR is the only class of magnetic resonance experiments for which the simulation problem is solved comprehensively for spin systems of any size. This paper contains a practical walkthrough for one of the many available simulation packages - Spinach. Its unique feature is polynomial complexity scaling: the ability to simulate large spin systems quantum mechanically and with accurate account of relaxation, diffusion, chemical processes and hydrodynamics. This paper is a gentle introduction written with a PhD student in mind...
September 5, 2017: Magnetic Resonance in Chemistry: MRC
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