Magnetic Resonance in Chemistry (Magn Reson Chem)

Publications in this journal

• Article: Simultaneous measurement of J(HH) and two different (n) J(CH) coupling constants from a single multiply edited 2D cross-peak.

  Josep Saurí, Teodor Parella
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  ABSTRACT: Three different J-editing methods (IPAP, E.COSY and J-resolved) are implemented in a single NMR experiment to provide spin-state-edited 2D cross-peaks from which a simultaneous measurement of different homonuclear and heteronuclear coupling constants can be performed. A new J-selHSQMBC-IPAP experiment is proposed for the independent measurement of two different (n) J(CH) coupling constants along the F2 and F1 dimensions of the same 2D cross-peak. In addition, the E.COSY pattern provides additional information about the magnitude and relative sign between J(HH) and (n) J(CH) coupling constants. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 05/2013;
• Article: Improved baseline in (29) Si NMR spectra of water glasses.

  Jan Schraml, Peter Sandor, Stefan Korec, Martin Krump, Bronislav Foller
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  ABSTRACT: It is shown by experiments that replacing one-pulse sequence by RIDE (ring down elimination) pulse sequence may dramatically improve the baseline of (29) Si NMR spectra and eliminate the signal from the probe. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 05/2013;
• Article: Complete NMR assignment of retinal and its related compounds.

  Kui-Wu Wang, Shi-Wie Wang, Qi-Zhen Du
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  ABSTRACT: Complete and unambiguous (1) H and (13) C NMR chemical shift assignments for all-trans-retinal, 13-cis-retinal, 11-cis-retinal and 9-cis-retinal (1-4) have been established by means of two-dimensional COSY, HSQC, HMBC and NOESY spectroscopic experiments. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: One-step synthesis of 6-acetamido-3-(N-(2-(dimethylamino) ethyl) sulfamoyl) naphthalene-1-yl 7-acetamido-4-hydroxynaphthalene-2-sulfonate and its characterization with 1D and 2D NMR techniques.

  Wei Zhang
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  ABSTRACT: A one-step method was reported for the synthesis of 6-acetamido-3-(N-(2-(dimethylamino) ethyl) sulfamoyl) naphthalene-1-yl 7-acetamido-4-hydroxynaphthalene-2-sulfonate by treating 7-acetamido-4-hydroxy-2-naphthalenesulfonyl chloride with equal moles of N, N-dimethylethylenediamine in acetonitrile in the presence of K2 CO3 . The chemical structure of the obtained compounds was characterized by MS, FTIR, (1) H NMR, (13) C NMR, gCOSY, TOCSY, gHSQC, and gHMBC. The chemical shift differences of (1) H and (13) C being δ 0.04 and 0.2, respectively, were unambiguously differentiated. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: (1) H-HRMAS NMR study of cold smoked Atlantic salmon (Salmo salar) treated with E-beam.

  Palmira Villa, David Castejón, Marta Herraiz, Antonio Herrera
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  ABSTRACT: (1) H High resolution magic angle spinning (HRMAS) NMR spectroscopic data in combination with principal components analysis and analysis of variance were used to differentiate between irradiated and non-irradiated cold-smoked Atlantic salmon (Salmo salar). NMR profiling was obtained, with a spectral acquisition time of less than 8 min, from a small sample size of intact white salmon muscle, by non-destructive analysis that includes a very simple and rapid sample preparation step. Results obtained enable the use of creatine, trimethylamine oxide and the sum of phosphorylcholine and glycerophosphorylcholine as diagnostic compounds to detect irradiation treatment. This study shows the potential of (1) H-HRMAS to be a rapid method for investigating compositional changes due to food processing as well as to confirm the presence or absence of some bioactive compounds in irradiated samples. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: Shancigusins E-I, five new glucosides from the tubers of Pleione yunnanensis.

  Hai-Ling Dong, Han-Qiao Liang, Chun-Lan Wang, Shun-Xing Guo, Jun-Shan Yang
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  ABSTRACT: Five new glucosides, shancigusins E-I (1-5) were isolated from the tubers of Pleione yunnanensis (Rolfe) together with 18 known compounds. The structures of these compounds were determined by extensive analyses of their spectroscopic data. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: Design, synthesis and spectroscopic characterisation of a focused library based on the polyandrocarpamine natural product scaffold.

  Paul S Baron, Juliette E Neve, David Camp, Lekha Suraweera, Ann Lam, John Lai, Lidija Jovanovic, Colleen Nelson, Rohan A Davis
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  ABSTRACT: A focused library based on the marine natural products polyandrocarpamines A (1) and B (2) has been designed and synthesised using parallel solution-phase chemistry. In silico physicochemical property calculations were performed on synthetic candidates in order to optimise the library for drug discovery and chemical biology. A library of ten 2-aminoimidazolone products (3-12) was prepared by coupling glycocyamidine and a variety of aldehydes using a one-step stereoselective aldol condensation reaction under microwave conditions. All analogues were characterised by NMR, UV, IR and MS. The library was evaluated for cytotoxicity towards the prostate cancer cell lines, LNCaP, PC-3 and 22Rv1. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: (1) H and (13) C NMR spectral assignments of 2'-hydroxychalcones.

  Yeonjoong Yong, Seunghyun Ahn, Doseok Hwang, Hyuk Yoon, Geunhyeong Jo, Young Hwa Kim, Sang Ho Kim, Dongsoo Koh, Yoongho Lim
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  ABSTRACT: Chalcones are of interest to medicinal chemists because their structures can be easily modified with various functional groups. The syntheses and biological activities of chalcones from natural sources are well known. In this study, 24 2'-hydroxychalcones bearing methoxy substituents were synthesized, among which five are new. The NMR data for all synthesized chalcones are described for the first time. The complete assignments of the (1) H and (13) C NMR data can be used for the identification of newly discovered and widely isolated, synthesized chalcones. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: Small carbon-carbon couplings in monosubstituted benzenes - their signs and magnitudes determined by HCSE method.

  Vratislav Blechta, Jan Schraml
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  ABSTRACT: Signed values of all intra-ring (2,3,4) J(C,C) couplings in nine monosubstituted benzenes (C6 H5 -X where X = F, Cl, Br, CH3 , OCH3 , Si(CH3 )3 , C ≡ N, NO, NO2 ) are experimentally determined as well as nine couplings to substituent carbons. It is confirmed that while all the vicinal intra-ring (3) J(C,C) are positive and all geminal (2) J(C2,C4) are negative, both signs are found for geminal (2) J(C1,C3) couplings. All the determined signs agree with those already predicted by theoretical calculations. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: The electronic origin of unusually large (n) JFN coupling constants in some fluoroximes.

  Denize C Favaro, Rubén H Contreras, Cláudio F Tormena
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  ABSTRACT: SOPPA(CCSD) calculations show that the FC term is the most important contribution to the through-space transmission of JFN coupling constants for the fluoroximes studied in this work. Because of the well-known behavior of FC term, a new rationalization for the experimental (TS) JFN SSCC is presented. It is mainly based on the overlap matrix (Sij ) between fluorine and nitrogen lone pairs obtained from NBO analyses. An expression is proposed to take into account the influence of the electronic density (Dij ) between coupled nuclei as well as the s% character at the site of the coupling nuclei of bonds and non-bonding electron pairs involved in Dij . In using this approach, a linear correlation between (TS) JFN versus Dij is obtained. The most important aspect of this rationalization is related to the facility for understanding the behavior of some unusual experimental coupling constants. It is shown that, at least in this case, the electronic origin of the so-called through-space coupling is transmitted through to the overlap of orbitals on the coupled atoms, suggesting that, at least for these compounds, instead of through-space coupling, it should better be dubbed as 'through overlapping orbital coupling'. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: Structural peculiarities of configurational isomers of 1-styrylpyrroles according to (1) Н, (13) С and (15) N NMR spectroscopy and density functional theory calculations: electronic and steric hindrance for planar structure.

  Andrei V Afonin, Igor A Ushakov, Dmitry V Pavlov, Elena Yu Schmidt, Marina Yu Dvorko
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  ABSTRACT: Comparative analysis of the (1) Н and (13) С NMR data for a series of the E and Z-1-styrylpyrroles, E and Z-1-(1-propenyl)pyrroles, 1-vinylpyrroles and styrene suggests that the conjugation between the unsaturated fragments in the former compounds is reduced. This is the result of the mutual influence of the donor p-π and π-π conjugation having opposite directions. According to the NMR data combined with the density functional theory calculations, the Z isomer of 1-styrylpyrrole has essentially a nonplanar structure because of the steric hindrance. However, the E isomer of 1-styrylpyrrole is also an out-of-plane structure despite the absence of a sterical barrier for the planar one. Deviation of the E isomer from the planar structure seems to be caused by an electronic hindrance produced by a mutual influence of the p-π and π-π conjugation. The structure of the E isomer of the 2-substituted 1-styrylpyrroles is similar to that of the 2-substituted 1-vinylpyrroles. The steric effects in the Z isomer of the 2-substituted 1-styrylpyrroles result in the large increase of the dihedral angle between planes of the pyrrole ring and double bond. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 04/2013;
• Article: Assignment of absolute configuration of 8α-hydroxy-13-hydroperoxylabd-14,17-dien-19,16;23,6α-diolide by computed NMR chemical shifts.

  Saeed K Amini
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  ABSTRACT: Unassigned configurations of 8α-hydroxy-13-hydroperoxylabd-14,17-dien-19,16;23,6α-diolide, extracted from Iranian salvia, in the C13 and C16 were assigned as S and R, respectively. Extensive ab initio calculations followed by chemical shift predictions were employed in this assignment. Predicted chemical shifts were correlated to experimental ones in order to find the correct configuration, shown here. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: HMBC-1,n-ADEQUATE spectra calculated from HMBC and 1,n-ADEQUATE spectra.

  Gary E Martin, Kirill A Blinov, R Thomas Williamson
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  ABSTRACT: Unsymmetrical and generalized indirect covariance processing methods provide a means of mathematically combining pairs of 2D NMR spectra that share a common frequency domain to facilitate the extraction of correlation information. Previous reports have focused on the combination of HSQC spectra with 1,1-, 1,n-, and inverted 1 JCC 1,n-ADEQUATE spectra to afford carbon-carbon correlation spectra that allow the extraction of direct (1 JCC ), long-range (n JCC , where n ≥ 2), and 1 JCC -edited long-range correlation data, respectively. Covariance processing of HMBC and 1,1-ADEQUATE spectra has also recently been reported, allowing convenient, high-sensitivity access to n JCC correlation data equivalent to the much lower sensitivity n,1-ADEQUATE experiment. Furthermore, HMBC-1,1-ADEQUATE correlations are observed in the F1 frequency domain at the intrinsic chemical shift of the 13 C resonance in question rather than at the double-quantum frequency of the pair of correlated carbons, as visualized by the n,1, and m,n-ADEQUATE experiments, greatly simplifying data interpretation. In an extension of previous work, the covariance processing of HMBC and 1,n-ADEQUATE spectra is now reported. The resulting HMBC-1,n-ADEQUATE spectrum affords long-range carbon-carbon correlation data equivalent to the very low sensitivity m,n-ADEQUATE experiment. In addition to the significantly higher sensitivity of the covariance calculated spectrum, correlations in the HMBC-1,n-ADEQUATE spectrum are again detected at the intrinsic 13 C chemical shifts of the correlated carbons rather than at the double-quantum frequency of the pair of correlated carbons. HMBC-1,n-ADEQUATE spectra can provide correlations ranging from diagonal (0 JCC or diagonal correlations) to 4 JCC under normal circumstances to as much as 6 JCC in rare instances. The experiment affords the potential means of establishing the structures of severely proton-deficient molecules. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: Synthesis, NMR spectroscopic characterization and structure of a divinyldisilazane-(triphenylphosphine)platinum(0) complex: observation of isotope-induced chemical shifts 1 Δ12/13 C(195 Pt).

  Bernd Wrackmeyer, Elena V Klimkina, Thomas Schmalz, Wolfgang Milius
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  ABSTRACT: Tetramethyldivinyldisilazane-(triphenylphosphine)platinum(0) was prepared, characterized in solid state by X-ray crystallography and in solution by multinuclear magnetic resonance spectroscopy (1 H, 13 C, 15 N, 29 Si, 31 P and 195 Pt NMR). Numerous signs of spin-spin coupling constants were determined by two-dimensional heteronuclear shift correlations (HETCOR) and two-dimensional 1 H/1 H COSY experiments. Isotope-induced chemical shifts 1 Δ12/13 C(195 Pt) were measured from 195 Pt NMR spectra of the title compound as well as of other Pt(0), Pt(II) and Pt(IV) compounds for comparison. In contrast to other heavy nuclei such as 199 Hg or 207 Pb, the "normal" shifts of the heavy isotopomers to low frequencies are found, covering a range of >500 ppb. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: Counterion influence on chemical shifts in strychnine salts.

  Athena E Metaxas, John R Cort
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  ABSTRACT: The highly toxic plant alkaloid strychnine is often isolated in the form of the anion salt of its protonated tertiary amine. Here, we characterize the relative influence of different counterions on (1) H and (13) C chemical shifts in several strychnine salts in D2 O, methanol-d4 (CD3 OD), and chloroform-d (CDCl3 ) solvents. In organic solvents but not in water, substantial variation in chemical shifts of protons near the tertiary amine was observed among different salts. These secondary shifts reveal differences in the way each anion influences electronic structure within the protonated amine. The distributions of secondary shifts allow salts to be easily distinguished from each other as well as from the free base form. Slight concentration dependence in chemical shifts of some protons near the amine was observed for two salts in CDCl3 , but this effect is small compared with the influence of the counterion. Distinct chemical shifts in different salt forms of the same compound may be useful as chemical forensic signatures for source attribution and sample matching of alkaloids such as strychnine and possibly other organic acid and base salts. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: (1) H and (13) C NMR analysis of 2-acetamido-3-mercapto-3-methyl-N-aryl-butanamides and 2-acetamido-3-methyl-3-nitrososulfanyl-N-aryl-butanamide derivatives.

  Rafael Germano Santana, Derisvaldo Rosa Paiva, Roberto da Silva Gomes, Adriana Karla C A Reis
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  ABSTRACT: The complete assignment of the (1) H and (13) C NMR spectra of various 2-acetamido-3-mercapto-3-methyl-N-aryl-butanamides and 2-acetamide-3-methyl-3-nitrososulfanyl-N-aryl-butanamides with p-methoxy, o-chloro and m-chloro substituents is reported. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: A comparison of magnetic resonance imaging methods for fluid content imaging in porous media.

  Colleen E Muir, Bruce J Balcom
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  ABSTRACT: Quantitative measurements are important for imaging fluid content in porous media. Conventional MRI methods suffer from contrast because of relaxation times in porous media, resulting in measurements of apparent fluid content, not the true fluid content. We compare four magnetic resonance imaging methods for fluid content imaging in several water-saturated reservoir core plugs: frequency-encoded spin echo, single point ramped imaging with T1 enhancement, hybrid spin echo single point imaging (SE-SPI), and T2 mapping SE-SPI. 1-D profiles obtained with each method were compared in terms of image quality, image sensitivity, and quantification of water content. The image quality of short T2 lifetime samples suffered from blurring in hybrid SE-SPI images. Image sensitivity was the highest in the profiles obtained with frequency-encoded spin echo. The quantification of frequency-encoded spin echo, T2 mapping SE-SPI, and hybrid SE-SPI suffered in core plugs with a significant population of short T2 components because of T2 attenuation. Overall, single point ramped imaging with T1 enhancement was found to be the most general method for fluid content imaging. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: Comparative molecular field analysis and comparative molecular similarity index analysis studies on 1 H NMR chemical shift of NH group of diaryl triazene derivatives.

  M K Rofouie, M Salahinejad, J B Ghasemi, A Aghaei
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  ABSTRACT: Comparative molecular field analysis (CoMFA), comparative molecular field analysis region focusing (CoMFA-RF) for optimizing the region for the final partial least square analysis, and comparative molecular similarity indices analysis (CoMSIA) methods were employed to develop three-dimensional quantitative structure-activity relationship (3D-QSAR) models of 1 H NMR chemical shift of NH proton of diaryl triazene derivatives. The best orientation was searched by all-orientation search (AOS) strategy to minimize the effect of the initial orientation of the structures. The predictive abilities of CoMFA-RF and CoMSIA models were determined using a test set of ten compounds affording predictive correlation coefficients of 0.721 and 0.754, respectively, indicating good predictive power. For further model validation, cross validation (leave one out), progressive scrambling, and bootstrapping were also applied. The accuracy and speed of obtained 3D-QSAR models for the prediction of 1 H NMR chemical shifts of NH group of diaryl triazene derivatives were greater compared to some computational well-known procedures. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;
• Article: Premicellar interaction of PEO-PPO-PEO triblock copolymers with partially hydrophobic alcohols: NMR study.

  Jaroslav Kříž, Jiří Dybal
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  ABSTRACT: The interactions of three alcohols, namely, 2-butanol (BuOH), 3-methyl-2-butanol (MeBuOH), and 3,3-dimethyl-2-butanol (Me2BuOH) with propylene oxide octamer (PO8) and the copolymers (EO)8 (PO)13 (EO)8 (L35) and (EO)13 (PO)30 (EO)13 (L64) in D2 O were studied using 13 C NMR spectra and relaxations and 1 H PFG NMR diffusion measurements. For L64, it was shown that the temperature at which the PO chain starts to change its conformation under dehydration decreases by 6 K for each additional methyl group in the alcohol molecule (i.e. with increasing its hydrophobicity), and the analogous conformation states are attained at temperatures approximately 10 K lower compared using ketonic analogs of the alcohols under the same conditions. Also, the first signs of L64 aggregation, according to the normalized diffusion coefficients, are at temperatures 7, 10, and 13 K lower for BuOH, MeBuOH, and Me2BuOH, respectively. These effects are much weaker for (PO)13 in L35 or nonexistent for (PO)8 in PO8, thus showing the role of cooperativity in dehydration and aggregation processes. According to diffusion measurements, the molar fraction of the alcohol hydrogen bonded to L64 increases with its hydrophobicity and, in an apparent conflict with thermodynamics, with increasing temperature at which also higher NOE can be observed. Strong hydrogen bond interaction, which is in cooperation with hydrophobic interaction, does not preclude the exchange between bound and free states of the alcohol, however. Using 13 C transverse relaxation, its correlation time is shown to be of the order of 10 ms. Copyright © 2013 John Wiley & Sons, Ltd.
  Magnetic Resonance in Chemistry 03/2013;