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Schraml J, Kubec R, Kučerová P. Determination of substitution sites in monosubstituted five-membered aromatic heterocycles. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2011; 49:147-150. [PMID: 21322011 DOI: 10.1002/mrc.2725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 12/14/2010] [Accepted: 12/15/2010] [Indexed: 05/30/2023]
Abstract
Similar magnitudes of proton-proton couplings across three, four, and five bonds and proton-carbon couplings across two and three bonds combined with difficult to predict substituent effects make the results of an indiscriminate use of routine (COSY, HSQC, HMBC, etc.) techniques for substitution site determination in C-monosubstituted five-membered heteroaromatics suspect. As demonstrated on two examples of natural products, the use of 1,1-ADEQUATE leads to unambiguous substitution site determination lending thus further support to suggested inclusion of 1,1-ADEQUATE data into computer-assisted structure elucidation (CASE) protocols.
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Baltisberger JH, Musapelo T, Sutton B, Reynolds A, Gurung L. Reduction of spin diffusion artifacts from 2D zfr-INADEQUATE MAS NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 208:70-75. [PMID: 21036081 DOI: 10.1016/j.jmr.2010.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 10/06/2010] [Accepted: 10/07/2010] [Indexed: 05/30/2023]
Abstract
The primary shortcoming of the z-filtered refocused INADEQUATE MAS NMR pulse sequence is the possibility of artifacts introduced during the z-filter due to spin diffusion where by extra peaks in the single-quantum dimension (from other sites in the molecule) appear correlated with a given double-quantum frequency. This is a problem when the spinning speeds are too slow (less than 15 kHz) to sufficiently average the proton-proton homonuclear dipolar couplings. This would be especially important when working with large volume rotors that are difficult to spin fast enough to completely average the homonuclear couplings. In our experiments we used the frequency-switched Lee-Goldberg (FSLG) method of homonuclear decoupling during the z-filter to remove the artifact peaks. This method has the advantage of being quite easy to setup and implement on most modern NMR spectrometers.
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53
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Reddy GNM, Caldarelli S. Maximum-quantum (MaxQ) NMR for the speciation of mixtures of phenolic molecules. Chem Commun (Camb) 2011; 47:4297-9. [DOI: 10.1039/c1cc10226e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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54
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George C, Chandrakumar N. (119/117/115)Sn low-abundance single-transition correlation spectroscopy (LASSY): sensitivity-enhanced homonuclear correlation experiments for Sn NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48:912-917. [PMID: 20882515 DOI: 10.1002/mrc.2686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report the implementation of our novel rare-spin homonuclear correlation experiment, namely, Low-Abundance Single-transition correlation SpectroscopY (LASSY), for (119/117/115)Sn NMR at natural abundance. Our pulse sequence results in diagonal suppressed COSY-style display and outperforms the optimal homonuclear correlation experiment for rare spins, which involves double quantum evolution (INADEQUATE CR). The new experiment maximizes efficiency both in respect of pulse transformations as well as relaxation effects, and gives rise to a simplified two-dimensional (2D) spectrum with considerably reduced crowding, exhibiting only one transition in each cross peak, instead of four. Performance optimization of LASSY is carried out in light of the relatively 'large' line widths typical of Sn NMR in solution state. The superior performance of the sequence is demonstrated on dimeric tetraorganodistannoxane samples.
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Affiliation(s)
- Christy George
- Department of Chemistry, Indian Institute of Technology-Madras, Chennai 600036, Tamil Nadu, India
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55
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Gebhard R, van der Hoef K, Lefeber AWM, Erkelens C, Lugtenburg J. Synthesis and spectroscopy of (14′-13C)- and (15′-13C)spheroidene. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19901090604] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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56
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Bain AD, Hughes DW, Anand CK, Nie Z, Robertson VJ. Problems, artifacts and solutions in the INADEQUATE NMR experiment. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48:630-641. [PMID: 20589732 DOI: 10.1002/mrc.2639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The INADEQUATE experiment can provide unequalled, detailed information about the carbon skeleton of an organic molecule. However, it also has the reputation of requiring unreasonable amounts of sample. Modern spectrometers and probes have mitigated this problem, and it is now possible to get good structural data on a few milligrams of a typical organic small molecule. In this paper, we analyze the experiment step by step in some detail, to show how each part of the sequence can both contribute to maximum overall sensitivity and can lead to artifacts. We illustrate these methods on three molecules: 1-octanol, the steroid 17alpha-ethynylestradiol and the isoquinoline alkaloid beta-hydrastine. In particular, we show that not only is the standard experiment powerful, but also a version tuned to small couplings can contribute vital structural information on long-range connectivities. If the delay in the spin echo is long, pairs of carbons with small couplings can create significant double-quantum coherence and show correlations in the spectrum. These are two- and three-bond correlations in a carbon chain or through a heteroatom in the molecule. All these mean that INADEQUATE can play a viable and important role in routine organic structure determination.
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Affiliation(s)
- Alex D Bain
- Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1.
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57
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Solid-State Nuclear Magnetic Resonance Spectroscopy: A Review of Modern Techniques and Applications for Inorganic Polymers. J Inorg Organomet Polym Mater 2010. [DOI: 10.1007/s10904-010-9358-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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59
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G. N. MR, Caldarelli S. Demixing of Severely Overlapping NMR Spectra through Multiple-Quantum NMR. Anal Chem 2010; 82:3266-9. [DOI: 10.1021/ac100009y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manjunatha Reddy G. N.
- Université Paul Cézanne (Aix-Marseille III) Equipe Chimiométrie et Spectroscopie, Institut des Sciences Moléculaires de Marseille ISM2-UMR-CNRS-6263. Faculté des Sciences et Techniques, Service 512 13397 Marseille Cedex 20 France
| | - Stefano Caldarelli
- Université Paul Cézanne (Aix-Marseille III) Equipe Chimiométrie et Spectroscopie, Institut des Sciences Moléculaires de Marseille ISM2-UMR-CNRS-6263. Faculté des Sciences et Techniques, Service 512 13397 Marseille Cedex 20 France
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60
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Ricci G, Leone G, Boglia A, Boccia AC, Zetta L. cis-1,4-alt-3,4 Polyisoprene: Synthesis and Characterization. Macromolecules 2009. [DOI: 10.1021/ma901864e] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Giovanni Ricci
- CNR-Istituto per lo Studio delle Macromolecole (ISMAC), via E. Bassini 15, I-20133 Milano, Italy
| | - Giuseppe Leone
- CNR-Istituto per lo Studio delle Macromolecole (ISMAC), via E. Bassini 15, I-20133 Milano, Italy
| | - Aldo Boglia
- CNR-Istituto per lo Studio delle Macromolecole (ISMAC), via E. Bassini 15, I-20133 Milano, Italy
| | | | - Lucia Zetta
- CNR-Istituto per lo Studio delle Macromolecole (ISMAC), via E. Bassini 15, I-20133 Milano, Italy
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61
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Bringmann G, Gulder TAM, Hamm A, Goodfellow M, Fiedler HP. Multiple convergence in polyketide biosynthesis: a third folding mode to the anthraquinone chrysophanol. Chem Commun (Camb) 2009:6810-2. [PMID: 19885487 DOI: 10.1039/b910501h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The polyketide chrysophanol is shown to be formed, in an organism-specific way, by a third folding mode, involving a remarkable cyclization of a bicyclic diketo precursor, thus establishing the first example of multiple convergence in polyketide biosynthesis.
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Affiliation(s)
- Gerhard Bringmann
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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62
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Bugaj M, Baran PA, Kamieńska-Trela K, Krówczyński A. Structural studies on aryl-substituted enaminoketones and their thio analogues. Part II. Experimental and DFT calculated carbon-carbon coupling constants, (n)J(CC)'s (n = 1-3). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2009; 47:843-856. [PMID: 19629950 DOI: 10.1002/mrc.2481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Spin-spin carbon-carbon coupling constants across one, two and three bonds, J(CC), have been measured for a series of aryl-substituted Z-s-Z-s-E enaminoketones and their thio analogues. As a result, a large set, altogether 178, of J(CC)s has been obtained. It consists of 82 couplings across one bond, 31 couplings across two bonds and 65 couplings across three bonds. Independently, the DFT calculations at the B3PW91/6-311++G(d,p)//B3PW91/6-311++G(d,p) level yielded a set of theoretical J(CC) values. A comparison of these two sets of data gave an excellent linear correlation with parameters a and b close to ideal; a = 0.9978 which is not far from unity and b = 0.22 Hz which is close to zero. The (1)J(CC) couplings determined for the crucial fragment of the molecules, i.e. -C=C-C=O (or -C=C-C=S), are: (1)J(C=C) approximately 68 Hz (67 Hz) and (1)J(C-C) = 60.5 Hz (60.0 Hz). The corresponding couplings found for the Z-s-Z-s-E isomer of the parent enaminoketone, 4-methylamino-but-3-en-2-one are 64.1 and 59.3 Hz, respectively. The most sensitive towards substitution of the oxygen atom by sulfur are two-bond couplings between the alpha-vinylic and aromatic C(ipso) carbon atoms, which attain 12 Hz in the enaminoketone derivatives and decrease to 5 Hz in their thio analogues.
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Affiliation(s)
- Marta Bugaj
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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63
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Zhou Z, Kümmerle R, Stevens JC, Redwine D, He Y, Qiu X, Cong R, Klosin J, Montañez N, Roof G. 13C NMR of polyolefins with a new high temperature 10 mm cryoprobe. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2009; 200:328-333. [PMID: 19665405 DOI: 10.1016/j.jmr.2009.07.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 07/14/2009] [Accepted: 07/15/2009] [Indexed: 05/28/2023]
Abstract
Recently, a high temperature 10 mm cryoprobe was developed. This probe provides a significant sensitivity enhancement for (13)C NMR of polyolefins at a sample temperature of 120-135 degrees C, as compared to conventional probes. This greatly increases the speed of NMR studies of comonomer content, sequence distribution, stereo- and regioerrors, saturated chain end, unsaturation, and diffusion of polymers. In this contribution, we first compare the (13)C NMR sensitivity of this probe with conventional probes. Then, we demonstrate one of the advantages of this probe in its ability to perform 2D Incredible Natural Abundance Double Quantum Transfer Experiment (2D INADEQUATE) in a relatively short period of time. The 2D INADEQUATE has been rarely used for polymer studies because of its inherently very low sensitivity. It becomes even more challenging for studying infrequent polyolefin microstructures, as low probability microstructures represent a small fraction of carbons in the sample. Here, the 2D INADEQUATE experiment was used to assign the (13)C NMR peaks of 2,1-insertion regioerrors in a poly(propylene-co-1-octene) copolymer.
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Affiliation(s)
- Zhe Zhou
- The Dow Chemical Company, Freeport, TX 77541, USA.
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64
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65
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66
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Martin GE, Smith SL, Layton WJ, Willcott MR, Iwao M, Lee ML, Castle RN. Assignment of the1H- and13C-NMR spectra of phenanthro[1,2-b]thiophene through the concerted application of two-dimensional NMR spectroscopic techniques. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.5570200542] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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67
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Lee D, Struppe J, Elliott DW, Mueller LJ, Titman JJ. Sensitive absorptive refocused scalar correlation NMR spectroscopy in solids. Phys Chem Chem Phys 2009; 11:3547-53. [PMID: 19421560 DOI: 10.1039/b818867j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new two-dimensional NMR experiment is described which is suitable for obtaining magic angle spinning (MAS) scalar correlation spectra in solids. The new experiment has several advantages, including increased cross peak intensities, coupled with good suppression of the diagonal. Its utility is demonstrated via assignments of the carbon-13 MAS spectra of progesterone at natural abundance and of the polymer phase of 50%-U-13C-CsC60.
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Affiliation(s)
- Daniel Lee
- School of Chemistry, University of Nottingham, University Park, Nottingham, UK NG7 2RD
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68
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Zhou Z, Stevens JC, Klosin J, Kümmerle R, Qiu X, Redwine D, Cong R, Taha A, Mason J, Winniford B, Chauvel P, Montañez N. NMR Study of Isolated 2,1-Inverse Insertion in Isotactic Polypropylene. Macromolecules 2009. [DOI: 10.1021/ma802770f] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhe Zhou
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - James C. Stevens
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Jerzy Klosin
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Rainer Kümmerle
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Xiaohua Qiu
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - David Redwine
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Rongjuan Cong
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Angela Taha
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Jeff Mason
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Bill Winniford
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Paul Chauvel
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
| | - Nikki Montañez
- Dow Chemical Company, Freeport, Texas 77541; Dow Chemical Company, Midland, Michigan 48667; Bruker BioSpin AG, CH-8117 Fällanden, Switzerland; and Kelly, Freeport, Texas 77541
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69
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Hiet J, Deschamps M, Pellerin N, Fayon F, Massiot D. Probing chemical disorder in glasses using silicon-29 NMR spectral editing. Phys Chem Chem Phys 2009; 11:6935-40. [DOI: 10.1039/b906399d] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Martineau C, Fayon F, Legein C, Buzaré JY, Goutenoire F, Suard E. Neutron Powder Diffraction, Multinuclear, and Multidimensional NMR Structural Investigation of Pb5Ga3F19. Inorg Chem 2008; 47:10895-905. [DOI: 10.1021/ic801044j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Charlotte Martineau
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
| | - Franck Fayon
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
| | - Christophe Legein
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
| | - Jean-Yves Buzaré
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
| | - François Goutenoire
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
| | - Emmanuelle Suard
- Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Laboratoire de Physique de l’Etat Condensé, CNRS UMR 6087, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, CNRS FR 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France, Conditions Extrêmes et Matériaux: Haute Température et Irradiation
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71
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Gschwind RM. Organocuprates and Diamagnetic Copper Complexes: Structures and NMR Spectroscopic Structure Elucidation in Solution. Chem Rev 2008; 108:3029-53. [DOI: 10.1021/cr800286r] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ruth M. Gschwind
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany
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72
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Patra A, Mahapatra T. Aliquat 336 Catalysed Three-Component Condensation in an Aqueous Media: A Synthesis of 1H- and 4H-benzochromenes. JOURNAL OF CHEMICAL RESEARCH 2008. [DOI: 10.3184/030823408785702490] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The synthesis, under microwave irradiation, of a series of polyfunctionalised 1 H- and 4H- chromenes in water in the presence of tricaprylmethylammonium bromide (Aliquat 336) as the catalyst is reported. This method has the advantages of high yields, neutral and inexpensive medium, simple work-up procedure and environmental friendliness.
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Affiliation(s)
- Amarendra Patra
- Department of Chemistry, University of Calcutta, University College of Science and Technology, 92, Acharya P.C. Road, Calcutta-700009, India
| | - Tanusri Mahapatra
- Department of Chemistry, University of Calcutta, University College of Science and Technology, 92, Acharya P.C. Road, Calcutta-700009, India
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73
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Hu B, Amoureux JP, Trebosc J, Deschamps M, Tricot G. Solid-state NMR covariance of homonuclear correlation spectra. J Chem Phys 2008; 128:134502. [DOI: 10.1063/1.2884341] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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74
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Lang M, Mühlbauer A, Gräf C, Beyer J, Lang-Fugmann S, Polborn K, Steglich W. Studies on the Structure and Biosynthesis of Tridentoquinone and Related Meroterpenoids from the MushroomSuillus tridentinus (Boletales). European J Org Chem 2008. [DOI: 10.1002/ejoc.200700908] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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75
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Martineau C, Fayon F, Legein C, Buzaré JY, Body M, Massiot D, Goutenoire F. Structure determination of β-Pb2ZnF6 by coupling multinuclear solid state NMR, powder XRD and ab initio calculations. Dalton Trans 2008:6150-8. [DOI: 10.1039/b810863c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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76
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Raabe I, Antonijevic S, Krossing I. Dynamics and Counterion-Dependence of the Structures of Weakly Bound Ag+–P4S3 Complexes. Chemistry 2007; 13:7510-22. [PMID: 17616955 DOI: 10.1002/chem.200601885] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In an earlier publication (J. Am. Chem. Soc. 2002, 124, 7111) we showed that polymeric cationic [Ag(P(4)S(3))(n)](+) complexes (n=1, 2) are accessible if partnered with a suitable weakly coordinating counterion of the type [Al(OR(F))(4)](-) (OR(F): poly- or perfluorinated alkoxide). The present work addresses the following questions that could not be answered in the initial report: How many P(4)S(3) cages can be bound to a Ag(+) ion? Why are these complexes completely dynamic in solution in the (31)P NMR experiments? Can these dynamics be frozen out in a low-temperature (31)P MAS NMR experiment? What are the principal binding sites of the P(4)S(3) cage towards the Ag(+) ion? What are likely other isomers on the [Ag(P(4)S(3))(n)](+) potential energy surface? Counterion influence: Reactions of P(4)S(3) with Ag[Al{OC(CH(3))(CF(3))(2)}(4)] (Ag[hftb]) and Ag[{(CF(3))(3)CO}(3)Al-F-Al{OC(CF(3))(3))}(3)] (Ag[al-f-al]) gave [(P(4)S(3))Ag[hftb]](infinity) (7) as a molecular species, whereas [Ag(2)(P(4)S(3))(6)](2+)[al-f-al](-) (2) (8) is an isolated 2:1 salt. We suggest that a maximum of three P(4)S(3) cages may be bound on average to an Ag(+) ion. Only isolated dimeric dications are formed with the largest cation, but polymeric species are obtained with all other smaller aluminates. Thermodynamic Born-Haber cycles, DFT calculations, as well as solution NMR and ESI mass spectrometry indicate that 8 exhibits an equilibrium between the dication [Ag(2)(P(4)S(3))(6)](2+) (in the solid state) and two [Ag(P(4)S(3))(3)](+) monocations (in the gas phase and in solution). Dynamics: (31)P MAS NMR spectroscopy showed these solid adducts to be highly dynamic, to an extent that the (2)J(P,P) coupling within the cages could be resolved (J-res experiment). This is supported by DFT calculations, which show that the extended PES of [Ag(P(4)S(3))(n)](+) (n=1-3) and [Ag(2)(P(4)S(3))(2)](+) is very flat. The structures of alpha- and gamma-P(4)S(3) were redetermined. Their variable-temperature (31)P MAS NMR spectra are discussed jointly with those of all four currently known [Ag(P(4)S(3))(n)](+) adducts with n=1, 2, and 3.
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Affiliation(s)
- Ines Raabe
- Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Analytische Chemie, Albertstrasse 21, 79104 Freiburg i. Br., Germany
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77
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Kurfürst M, Schraml J. 2J(29Si-O-29Si) coupling constants in oligosiloxanes. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45:685-7. [PMID: 17559159 DOI: 10.1002/mrc.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The absolute values of spin-spin couplings between (29)Si nuclei in siloxanes, (2)J((29)Si-O-(29)Si), were determined. The couplings are small and cover a narrow range of values (0-5 Hz). The coupling constants depend on the branching or on the number of electronegative substituents on the Si-O-Si moiety.
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Affiliation(s)
- Milan Kurfürst
- Institute of Chemical Process Fundamentals of the ASCR, v.v.i, 16502 Prague 6, Czech Republic
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78
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Bringmann G, Noll TF, Gulder T, Dreyer M, Grüne M, Moskau D. Polyketide Folding in Higher Plants: Biosynthesis of the Phenylanthraquinone Knipholone. J Org Chem 2007; 72:3247-52. [PMID: 17388630 DOI: 10.1021/jo062566x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biosynthesis of knipholone, as an axially chiral phenylanthraquinone, in higher plants was examined by feeding experiments with [13C2]-labeled precursors. [13C2]-Acetate and advanced synthetic intermediates were fed to sterile cultures of Kniphofia pumila (Asphodelaceae), with subsequent NMR analysis on the isolated natural product involving 2D INADEQUATE and SELINQUATE experiments. Due to its uneven number of carbon atoms, and because of its uncertain decarboxylation site, the "northern" part of the molecule (i.e., the chrysophanol portion) might originate from four different cyclization modes. According to the labeling pattern of the product isolated after incorporation, this anthraquinone part of knipholone is formed by the so-called F folding mode (originally established for fungi). The acetophenone part of the molecule, which does not undergo a decarboxylation reaction, originates from four acetate units. The surprising lack of randomization of the intact [13C2] units in this "southern" part reveals the absence of a free symmetric intermediate as initially anticipated. This is in agreement with the intact incorporation of the "authentic" southern molecular portion, 4,6-dihydroxy-2-methoxyacetophenone, while the corresponding symmetrical candidate trihydroxyacetophenone was clearly not incorporated, showing that the O-methylation of the freshly cyclized tetraketide is the step that prevents symmetrization of the acetophenone.
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Affiliation(s)
- Gerhard Bringmann
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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79
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Munowitz M, Pines A. Principles and Applications of Multiple-Quantum Nmr. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470142929.ch1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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80
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Verel R, Manolikas T, Siemer AB, Meier BH. Improved resolution in (13)C solid-state spectra through spin-state-selection. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 184:322-9. [PMID: 17088090 DOI: 10.1016/j.jmr.2006.09.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 09/21/2006] [Accepted: 09/26/2006] [Indexed: 05/12/2023]
Abstract
The application of a spin-state-selective coherence transfer experiment (INADEQUATE-SSS) to solid-state NMR spectroscopy is described. Two-dimensional (13)C double-quantum/single-quantum spectra without J splittings in both dimensions lead to enhanced spectral resolution. The method is demonstrated to significantly improve the spectral resolution of the crowded C'-C(alpha) region of two proteins.
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Affiliation(s)
- René Verel
- Physical Chemistry, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
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81
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Bax A, Egan W, Ková P. New NHR Techniques for Structure Determination and Resonance Assignments of Complex Carbohydrates. J Carbohydr Chem 2006. [DOI: 10.1080/07328308408057920] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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82
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Fukushi E. Advanced NMR approaches for a detailed structure analysis of natural products. Biosci Biotechnol Biochem 2006; 70:1803-12. [PMID: 16926490 DOI: 10.1271/bbb.50663] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Some new nuclear magnetic resonance (NMR) approaches to elucidate chemical structures, which have not been determined by routine NMR methods, are presented. Selective detection of methine (CH), methylene (CH(2)), or methyl (CH(3)) signals in each subspectrum by editing NMR methods was utilized to reduce the complexity in crowded spectra. It also increased the peak separation and enhanced the sensitivity by limiting the measuring area of the 2D spectra. Several 2D methods to measure (2,3)J(CH) values, which are useful for stereochemical assignment are then introduced. To determine the structure of a highly hydrogen-deficient molecule, efficient correlation methods for long-range (13)C-(13)C coupling and (1)H-(15)N HMBC are also described.
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Affiliation(s)
- Eri Fukushi
- Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
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83
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D'avignon DA, Hanau CE, Fobian YM, Moeller KD. APPLICATION OF HMBC AND HMQC-TOCSY NMR METHODS TO ASSIGN THE STRUCTURES OF BICYCLIC-PEPTIDE MIMETICS. J COORD CHEM 2006. [DOI: 10.1080/00958979408024243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- D. André D'avignon
- a Department of Chemistry , Washington University , Campus Box 1134, St. Louis, MO, 63130
| | - Cathleen E. Hanau
- a Department of Chemistry , Washington University , Campus Box 1134, St. Louis, MO, 63130
| | - Yvette M. Fobian
- a Department of Chemistry , Washington University , Campus Box 1134, St. Louis, MO, 63130
| | - Kevin D. Moeller
- a Department of Chemistry , Washington University , Campus Box 1134, St. Louis, MO, 63130
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84
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Gochin M, Pines A, Rosen M, Rucker S, Schmidt C. Two-dimensional N.M.R. studies of flexible molecules in liquid crystals: orientational order and conformational probabilities ofn-hexane. Mol Phys 2006. [DOI: 10.1080/00268979000100501] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- M. Gochin
- a Materials and Chemical Sciences Division , Lawrence Berkeley Laboratory , 1 Cyclotron Road, Berkeley , California , 94720 , U.S.A
- b Department of Chemistry , University of California , Berkeley , California , 94720 , U.S.A
- c Department of Pharmaceutical Chemistry , University of California , San Francisco , California , 94143 , U.S.A
| | - A. Pines
- a Materials and Chemical Sciences Division , Lawrence Berkeley Laboratory , 1 Cyclotron Road, Berkeley , California , 94720 , U.S.A
- b Department of Chemistry , University of California , Berkeley , California , 94720 , U.S.A
| | - M.E. Rosen
- a Materials and Chemical Sciences Division , Lawrence Berkeley Laboratory , 1 Cyclotron Road, Berkeley , California , 94720 , U.S.A
- b Department of Chemistry , University of California , Berkeley , California , 94720 , U.S.A
| | - S.P. Rucker
- a Materials and Chemical Sciences Division , Lawrence Berkeley Laboratory , 1 Cyclotron Road, Berkeley , California , 94720 , U.S.A
- b Department of Chemistry , University of California , Berkeley , California , 94720 , U.S.A
| | - C. Schmidt
- a Materials and Chemical Sciences Division , Lawrence Berkeley Laboratory , 1 Cyclotron Road, Berkeley , California , 94720 , U.S.A
- b Department of Chemistry , University of California , Berkeley , California , 94720 , U.S.A
- d Institut für Makromolekulare Chemie, Universität Freiburg , Stefan-Meier-Strasse 31, D-7800 , Freiburg , F.R. Germany
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85
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86
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Bringmann G, Noll TF, Gulder TAM, Grüne M, Dreyer M, Wilde C, Pankewitz F, Hilker M, Payne GD, Jones AL, Goodfellow M, Fiedler HP. Different polyketide folding modes converge to an identical molecular architecture. Nat Chem Biol 2006; 2:429-33. [PMID: 16829953 DOI: 10.1038/nchembio805] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 06/13/2006] [Indexed: 11/08/2022]
Abstract
Metabolic diversity is being studied intensively by evolutionary biologists, but so far there has been no comparison of biosynthetic pathways leading to a particular secondary metabolite in both prokaryotes and eukaryotes. We have detected the bioactive anthraquinone chrysophanol, which serves as a chemical defense in diverse eukaryotic organisms, in a bacterial Nocardia strain, thereby permitting the first comparative biosynthetic study. Two basic modes of folding a polyketide chain to fused-ring aromatic structures have so far been described: mode F (referring to fungi) and mode S (from Streptomyces). We have demonstrated that in eukaryotes (fungi, higher plants and insects), chrysophanol is formed via folding mode F. In actinomycetes, by contrast, the cyclization follows mode S. Thus, chrysophanol is the first polyketide synthase product that is built up by more than one polyketide folding mode.
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Affiliation(s)
- Gerhard Bringmann
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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87
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Pérez-Hernández N, Morales-Ríos MS, Cerda-García-Rojas CM, Joseph-Nathan P. Conformational evaluation and detailed 1H and 13C NMR assignments of flavoxate, a urinary tract antispasmodic agent. J Pharm Biomed Anal 2006; 41:603-9. [PMID: 16426792 DOI: 10.1016/j.jpba.2005.11.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2005] [Revised: 11/21/2005] [Accepted: 11/22/2005] [Indexed: 11/19/2022]
Abstract
1H and 13C NMR chemical shift assignments for the urinary tract antispasmodic flavoxate (1) and flavoxate hydrochloride (2) were obtained from one- and two-dimensional measurements. A Monte Carlo random search using molecular mechanics, followed by geometry optimization of each minimum energy structure employing DFT calculations at the B3LYP/6-31G* level, and a Boltzmann analysis of the total energies, provided accurate molecular models which describe the conformational behavior of flavoxate (1). The electron density surfaces for the global minimum and the second minimum conformers 1a and 1b of this L-type Ca2+ channel inhibitor were calculated. The presence of both conformers in solution was demonstrated in full agreement with 2D NOESY data and NOE difference spectroscopy.
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Affiliation(s)
- Nury Pérez-Hernández
- Centro de Investigación en Biología de la Reproducción, Campus Sahagún, Universidad Autónoma del Estado de Hidalgo, Apartado 1-622, Pachuca, Hidalgo 42001, Mexico
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88
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Fukushi E, Kawabata J. Application of 1D BIRD or X-filtered DEPT long-range C-C relay for detection of proton and carbon via four bonds and measuring long-range 13C-13C coupling constants. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2006; 44:475-80. [PMID: 16395733 DOI: 10.1002/mrc.1768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We propose the 13C-detecting 1D DEPT long-range C-C relay to detect super long-range H-C connectivity via four bonds (1H-13C-X-X-13C, X represents 12C or heteronuclear). It is derived from the DEPT C-C relay which detects the H-C correlations via two bonds (1H-13C-13C) by setting the delays for J(CC) in the C-C relay sequence to the (LR)J(CC). This sequence gives correlation signals split by small (LR)J(CC), which seriously suffers from residual center signal. The unwanted signal is due to long-range C-H couplings ((LR)J(CH)). The expected relayed magnetization transfer 1J(CH) --> (LR)J(CC) occurs in the 1H-13C-X-(X)-13C isotopomer, whereas the unwanted signal of (LR)J(CH) comes from 1H-12C-(X)-13C isotopomers, whose population is 100 times larger than that of the 1H-13C-X-(X)-13C isotopomer. The large dispersive line of this unwanted center signal would be a fatal problem in the case of detecting small (LR)J(CC) couplings. This central signal could be removed by an insertion of BIRD pulse or X-filter. DEPT spectrum editing solved a signal overlapping problem and enabled accurate determination of particular (LR)J(CC) values. We demonstrate here the examples of structure determination using connectivity between 1H and 13C via four bonds, and the application of long-range C-C coupling constants to discrimination of stereochemical assignments.
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Affiliation(s)
- Eri Fukushi
- Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
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89
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Fayon F, Roiland C, Emsley L, Massiot D. Triple-quantum correlation NMR experiments in solids using J-couplings. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 179:49-57. [PMID: 16307897 DOI: 10.1016/j.jmr.2005.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 11/03/2005] [Accepted: 11/03/2005] [Indexed: 05/05/2023]
Abstract
We show that triple-quantum-single-quantum (TQ-SQ) correlation spectra of crystalline and disordered solids can be obtained under MAS using pulse sequences based on through-bond J-couplings. The feasibility of the experiments in coupled spin-1/2 systems is demonstrated for fully 13C-labelled L-alanine and Pb3P4O13 crystalline compounds, considered as model three-spin and four-spin systems, respectively. In the case of phosphate glasses, we show that the obtained TQ-SQ correlation spectra provide an improved description of the glass forming network connectivities and of the chain length distribution in the disordered network.
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Affiliation(s)
- Franck Fayon
- Centre de Recherches sur les Matériaux à Haute Température, CNRS, 45071 Orléans cedex 2, France.
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90
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Nyberg NT, Duus JØ, Sørensen OW. Editing of H2BC NMR spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:971-4. [PMID: 16142835 DOI: 10.1002/mrc.1698] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
New versions of the H2BC pulse sequence (Nyberg NT, Duus JØ, Sørensen OW. J. Am. Chem. Soc. 2005; 127: 6154) that edit into two subspectra according to the number of protons attached to 13C nuclei being odd or even are introduced. These sequences can be useful for resolving spectral overlap, which is demonstrated on the molecule prednisolone [(11 beta)-11,17,21-trihydroxypregna-1,4-diene-3,20-dione].
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Affiliation(s)
- Nils T Nyberg
- Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
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91
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Taurian OE, De Kowalewski DG, Pérez JE, Contreras RH. NMR J(13C,13C) spin–spin coupling constants in pyridine-carboxaldehydes. Experimental and DFT-B3LYP studies. J Mol Struct 2005. [DOI: 10.1016/j.molstruc.2005.06.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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92
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Schraml J, Tkadlecová M, Pataridis S, Soukupová L, Blechta V, Roithová J, Exner O. Ring-substituted benzohydroxamic acids: 1H, 13C and 15N NMR spectra and NH-OH proton exchange. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:535-542. [PMID: 15861383 DOI: 10.1002/mrc.1586] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
NMR spectra (1H, 13C, 15N) of para- and meta-substituted benzohydroxamic acids were studied in dry dimethyl sulfoxide solutions. The 13C chemical shifts were very close to those found by cross-polarization magic angle spinning in solids, the hydroxamic (not hydroximic) structure of which is unambiguous. The hydroxamic structure of these acids in DMSO solutions was proved independently by their 15N chemical shifts. The 15N and 1H chemical shifts of the NH-OH fragment showed excellent mutual dependences and dependences on the nature of the ring substituent. According to these dependences and ab initio energy calculations, all the acids assume the same Z conformation. Proton exchange between hydroxamic OH and NH groups in DMSO proceeded by both intra- and intermolecular exchange and the rates did not exhibit any simple relationship to the substituent constants.
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Affiliation(s)
- Jan Schraml
- Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 16502 Prague 6, Czech Republic.
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93
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Commodari F, Khiat A, Ibrahimi S, Brizius AR, Kalkstein N. Comparison of the phytoestrogen trans-resveratrol (3,4',5-trihydroxystilbene) structures from x-ray diffraction and solution NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:567-572. [PMID: 15809979 DOI: 10.1002/mrc.1583] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The NMR-derived solution structure of trans-3,4',5-trihydroxystilbene (resveratrol) was compared with two recent literature crystal x-ray structures, resveratrol in complex with human transthyretin (TTR-RES) from 1DVS.pdb and resveratrol bound to chalcone synthase (CHS-RES) from 1CGZ.pdb. 1H and 13C NMR spectra of resveratrol were acquired in DMSO-d6. Assignments were obtained from an analysis of DQF-COSY, TOCSY, DEPT, HMQC/HSQC, HMBC and INADEQUATE NMR spectra. Past 1H and 13C NMR literature assignments are corrected. The dihedral angle 2-1-1'-2' provides an indication of the relative spatial orientation of the two phenolic rings. Values of 1.62, - 54.10 and 12.6 +/- 1.1 degrees were found for the 1DVS.pdb, 1CGZ.pdb and NMR resveratrol structures, respectively. The 1DVS.pdb resveratrol structure is 'flat' with the two phenolic rings along the same plane. The 1CGZ.pdb structure has these two rings almost orthogonal to each other, and the NMR structure has these two rings much closer to being along the same plane. The angles 1-alpha--alpha' and 1'-alpha'--alpha are along the same trace and of similar magnitude for the 1CGZ.pdb and NMR resveratrol structures. For the 1DVS.pdb resveratrol structure, these angles are about 7-10 degrees greater, with alpha and alpha' being 180 degrees out-of-phase from the other two structures. The alpha rings did not overlap, with the NMR result representing a 'median model' of the two x-ray structures.
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Affiliation(s)
- Fernando Commodari
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
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94
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Zhang F, Trbovic N, Wang J, Brüschweiler R. Double-quantum biased covariance spectroscopy: application to the 2D INADEQUATE experiment. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2005; 174:219-222. [PMID: 15862237 DOI: 10.1016/j.jmr.2005.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 02/09/2005] [Accepted: 02/09/2005] [Indexed: 05/24/2023]
Abstract
A novel processing scheme is presented that converts a two-dimensional double-quantum NMR spectrum into a single-quantum correlation spectrum. The covariance-like spectrum is computed from the 2D Fourier transform spectrum by emphasizing contributions that fulfill the double-quantum condition resulting in a symmetric spectrum that is easier to analyze. The method is demonstrated for the 2D INADEQUATE experiment.
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Affiliation(s)
- Fengli Zhang
- Carlson School of Chemistry and Biochemistry, Clark University, Worcester, MA 01610, USA
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95
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Merlet D, Lesage A, Emsley JW. Magnetic Field Induced Dipolar Couplings in the Pretransitional Region of a Nematic Liquid Crystal. J Phys Chem A 2005; 109:5070-8. [PMID: 16833860 DOI: 10.1021/jp050665t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
13C and 1H NMR spectroscopy have been used to study the orientational order which develops when a nematogenic compound, 4-pentyl-4'-cyanobiphenyl (5CB), approaches the transition from the isotropic to the nematic phase at T(NI). The experiments yield values of field induced dipolar couplings, (1), between all of the directly bonded carbon and hydrogen nuclei in the molecule, and 2D(HH)B, the geminal dipolar coupling between protons in the first methylene group in the alkyl chain. The temperature dependence of these couplings shows that in each case they follow a divergence behavior governed by (T - T*)(-1),where T* is a temperature determined from the experimental data and which is close to but less than T(NI). Experiments performed at spectrometer field strengths of 11.75 and 18.79 T confirm the prediction that the induced couplings should depend on the square of the applied field strength. It was found that, within experimental error, T* is the same for each field-induced coupling, and that T(NI) - T* is the same at 11.75 and 18.79 T. It is shown that the set of field-induced couplings 1D(CHi)B obtained at a temperature close to T(NI) can be used to derive a conformer distribution for 5CB in the isotropic phase.
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Affiliation(s)
- Denis Merlet
- Laboratoire de Chimie Structurale Organique, ICMMO, ESA 8074, Bât. 410, Université de Paris-Sud, 91405 Orsay, France.
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96
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de Macedo FC, Marsaioli AJ. Total structural assignment and absolute configuration of terreinol by 13C and 1H NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:251-255. [PMID: 15625725 DOI: 10.1002/mrc.1531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The carbon-carbon connectivity of terreinol, a new metabolite isolated from Aspergillus terreus, and its previous (13)C assignments were confirmed by a two-dimensional INADEQUATE experiment using a few milligrams of the compound with natural (13)C abundance. The carbon-carbon correlations were determined by computational analysis (with >99% probability) of this experiment. Additionally, the absolute configuration of terreinol was achieved indirectly via its corresponding secondary alcohol by the modified Mosher method allied to conformational analysis. The shielding effect of the phenyl group of methoxytrifluoromethylphenylacetic acid (MTPA) on the substituents of the carbonylic centre gave a fully regular Deltadelta(SR) sign distribution, allowing reliable assignment of the R configuration for terreinol.
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Welsch F. The mechanism of ethylene glycol ether reproductive and developmental toxicity and evidence for adverse effects in humans. Toxicol Lett 2005; 156:13-28. [PMID: 15705484 DOI: 10.1016/j.toxlet.2003.08.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Numerous experimental studies have established that only a few among the large family of ethylene glycol ethers (EGEs) elicit toxicity on reproduction in either gender. Notable are the monomethyl (EGME) and monoethyl (EGEE) ethers and their respective acetate esters whose production volumes have dramatically declined. Oxidation to the respective monoalkoxy acids is a prerequisite for toxicity. The most potent EGE reproductive toxicant is EGME (via 2-methoxyacetic acid; MAA), which elicits developmental phase-specific insults on either conceptus or on testes. Toxicity at either target site is markedly attenuated by simple physiological compounds such as acetate, formate, glycine, D-glucose and serine. Lack of solid EGME occupational exposure data and the need to improve the scientific foundations for animal data extrapolations, prompted the development of physiologically based pharmacokinetic (PBPK) models for pregnancy application. Interspecies (mouse-rat) and different exposure routes (including inhalation) were experimentally validated. Such PBPK models were then extrapolated to potential occupational exposures, using rather limited human MAA pharmacokinetic data. PBPK model predictions of human blood levels upon simulated inhalation exposure to the 5 ppm threshold limit value (TLV) for 8 h were approximately 60 microM were well below those causing adverse effects in pregnant mice or rats. This conclusion concurs with the lack of objective analytical chemistry data for EGME/MAA in occupational settings, regardless of the potential route of exposure. There are no exposure data that can be linked in a cause-and-effect association to adverse human reproductive outcomes.
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Affiliation(s)
- Frank Welsch
- Orbitox, International Toxicology Consultants, 1 Caliente Place, Santa Fe, NM 87508, USA.
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Bross-Walch N, Kühn T, Moskau D, Zerbe O. Strategies and Tools for Structure Determination of Natural Products Using Modern Methods of NMR Spectroscopy. Chem Biodivers 2005; 2:147-77. [PMID: 17191970 DOI: 10.1002/cbdv.200590000] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nadja Bross-Walch
- Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich
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99
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Yan J, Zartler ER. Application of residual dipolar couplings in organic compounds. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:53-64. [PMID: 15578593 DOI: 10.1002/mrc.1505] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Residual dipolar couplings (RDCs) induced by anisotropic media are a powerful tool for the structure determination of biomolecules through NMR spectroscopy. Recent advances have proven it to be a valuable tool for determination of the stereochemistry of organic molecules. By simple inspection or order matrix calculations, RDCs provide unambiguous information about the relative configurations or complete stereochemistry of organic compounds.
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Affiliation(s)
- Jiangli Yan
- Triad Therapeutics, Inc., San Diego, CA 92121, USA.
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100
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De Kowalewski DG, Contreras * RH, Díez E, Esteban A. NMRJ(C,C) scalar coupling analysis of the effects of substituents on the keto–enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study. Mol Phys 2004. [DOI: 10.1080/00268970412331292902] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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