Magnetic Resonance in Chemistry

Cover image for Vol. 50 Issue S1

Supplement: NMR of Small Molecules in Anisotropic Media

December 2012

Volume 50, Issue Supplement S1

Pages S1–S101

Issue edited by: Roberto R. Gil

  1. NMR of Small Molecules in Anisotropic Media. Wiley has published this supplement with no external financial support.

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    2. NMR of Small Molecules in Anisotropic Media. Wiley has published this supplement with no external financial support.
    1. Editorial

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    2. Deuterium NMR Spectroscopy

      Analytical contribution of NAD 2D-NMR spectroscopy in polypeptide mesophases to the investigation of triglycerides (pages S2–S11)

      Philippe Lesot, Zeinab Serhan, Christie Aroulanda and Isabelle Billault

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3855

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      Short and long-chain homogeneous saturated triglycerides are analyzed using natural abundance deuterium two-dimensional NMR spectroscopy in polypeptide achiral and chiral mesophases. The origin of spectrally observed diastereodiscrimination and enantiodiscrimination results from an average orientational behavior that differs for both types of solutes and can be explained in terms of molecular shape mechanisms.

      Corrected by:

      Erratum: Analytical contribution of NAD 2D-NMR spectroscopy in polypeptide mesophases to the investigation of triglycerides

      Vol. 51, Issue 7, 444–445, Article first published online: 14 JUN 2013

    3. The use of exchangeable nuclei to observe enantiomers through deuterium NMR in chiral liquid crystalline solvents (pages S12–S16)

      Martina Palomino, Hussein Khudr, Jacques Courtieu, Denis Merlet and Abdelkrim Meddour

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3857

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      2H NMR in chiral liquid crystalline solvents can be used to measure enantiomeric excesses using exchangeable deuterons in alcohols. This is performed in a trivial way at low temperature (260–270 K) where a slow exchange regime was reached.

    4. Stretched Polymer Gels

      7Li+ NMR quadrupolar splitting in stretched hydrogels: developments in relaxation time estimation from z-spectra (pages S17–S21)

      Max Puckeridge, Bogdan E. Chapman and Philip W. Kuchel

      Article first published online: 6 JUL 2012 | DOI: 10.1002/mrc.3841

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      NMR z-spectra were recorded from 7Li+ constituted in stretched gelatin gel and the relaxation times including those of the high-rank high-order spin states were estimated by both multiple-quantum-filtered spectra and a global data-fitting strategy.

    5. Noncovalently and covalently cross-linked polyurethane gels as alignment media and the suppression of residual polymer signals using diffusion-filtered spectroscopy (pages S22–S28)

      Peter Kaden, J. Christoph Freudenberger and Burkhard Luy

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3887

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      With polyurethane, a novel alignment medium for organic solvents is introduced and characterized. Linear polyurethane already constitutes an elastomer gel with several solvents based on its ability to form hydrogen bonds. Covalent cross-linking of the polymer with accelerated electrons provides an alignment medium with different properties. Additionally, we demonstrate the applicability of diffusion-filtered experiments for removal of the polymer signals while retaining the signals of the aligned molecules.

    6. Influence of solvent and salt concentration on the alignment properties of acrylamide copolymer gels for the measurement of RDC (pages S29–S37)

      Pablo Trigo-Mouriño, Armando Navarro-Vázquez and Víctor M. Sánchez-Pedregal

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3889

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      The dependence of molecular alignment with solvent nature and salt concentration has been investigated for mechanically stretched polyacrylamide copolymer gels. Residual dipolar couplings of N-methylcodeinium iodide were recorded in water, DMSO-d6, and DMSO-d6/D2O solutions containing different proportions of the solvents and different sodium chloride concentrations. The observed differences in the alignment of the solute molecule are most likely due to the influence of the swelling solution on the structure of the gel.

    7. Chiral Discrimination

      Chiral discrimination of amines by anisotropic NMR parameters using chiral polyacrylamide-based gels (pages S38–S44)

      Manuel Schmidt, Han Sun, Andrei Leonov, Christian Griesinger and Uwe M. Reinscheid

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3886

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      A chiral weakly aligning dimethyl sulfoxide compatible gel is presented by which a successful enantiomeric discrimination of three compounds is achieved. The discrimination is based exclusively on CH residual dipolar couplings demonstrating the usefulness of the approach.

    8. Phenylalanine-based polyarylacetylenes as enantiomer-differentiating alignment media (pages S45–S52)

      Alexis Krupp and Michael Reggelin

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3894

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      Lyotropic liquid crystalline phases of a phenylalanine-based polyacetylene are introduced as new enantiodifferentiating alignment media. Based on the unusual temperature dependence of the quadrupolar splitting of the 2H-signal of the solvent (CDCl3), three distinct states of the phase with different orientational properties can be identified.

    9. Pulse Sequences

      Fast access to residual dipolar couplings by single-scan 2D NMR in oriented media (pages S53–S57)

      Patrick Giraudeau, Tobias Montag, Benoît Charrier and Christina M. Thiele

      Article first published online: 5 AUG 2012 | DOI: 10.1002/mrc.3856

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      RDCs à la minute. This article shows the first measurement of residual dipolar couplings (RDCs) from single-scan two-dimensional NMR. RDCs of acceptable accuracy are obtained in as little time as 60 s on an organic compound at natural abundance.

      Corrected by:

      Erratum: Fast access to residual dipolar couplings by single-scan 2D NMR in oriented media

      Vol. 51, Issue 3, 192, Article first published online: 1 FEB 2013

    10. HR-HSBC: Measuring heteronuclear one-bond couplings with enhanced resolution (pages S58–S62)

      Benjamin Görling, Stefan Bräse and Burkhard Luy

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3878

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      A slightly modified version of the HR-HMBC for heteronuclear one-bond coupling measurements is introduced, which potentially is able to resolve partially overlapping signals because of the J-resolved-like tilt of corresponding multiplet patterns. The pulse sequence is introduced, and its performance is compared with an ω2-coupled HSQC experiment. Two examples provide evidence for its resolving power.

    11. A systematic approach for optimizing the robustness of pulse sequence elements with respect to couplings, offsets, and B1-field inhomogeneities (COB) (pages S63–S72)

      Sebastian Ehni and Burkhard Luy

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3846

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      An optimization strategy is introduced that allows the development of time-optimal pulse sequence elements that have robustness against variations in couplings, offsets, and B-field inhomogeneities (COB). As an example we present the 1H, 13C-COB-INEPT with >99% transfer.

    12. Software for Data Analysis

      MSpin-RDC. A program for the use of residual dipolar couplings for structure elucidation of small molecules (pages S73–S79)

      Armando Navarro-Vázquez

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3905

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      A new program, MSpin-RDC, has been developed to assist structural elucidation of small molecules using residual dipolar couplings. Analysis of conformationally flexible systems, including population fitting, is available through the single-tensor approximation. Residual chemical shift anisotropy data can be analyzed by extraction of shielding tensors from quantum-chemical shift computation files.

    13. Carbohydrates - a Mini Review

      Review: use of residual dipolar couplings to determine the structure of carbohydrates (pages S80–S85)

      A. Canales, J. Jiménez-Barbero and M. Martín-Pastor

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3888

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      The measurement of residual dipolar couplings in aligned samples provides long-range structural information, a valuable complement for the structural study of carbohydrates. This article reviews the current application of the residual dipolar couplings methodology to carbohydrates.

    14. Data Analysis

      New strategy for RDC-assisted diastereotopic proton assignment using a combination of J-scaled BIRD HSQC and J-scaled BIRD HMQC/HSQC (pages S86–S91)

      Jonathan D. Snider, Eduardo Troche-Pesqueira, Shannon R. Woodruff, Chakicherla Gayathri, Nicolay V. Tsarevsky and Roberto R. Gil

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3895

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      A method to assign diastereotopic protons by residual dipolar couplings (RDCs) that do not rely on permutation of assignments. Methylene protons do not need to be assigned to calculate the alignment tensor.

    15. Configuration verification via RDCs on the example of a tetra-substituted pyrrolidine ring (pages S92–S101)

      Pavleta Tzvetkova, Burkhard Luy and Svetlana Simova

      Article first published online: 21 DEC 2012 | DOI: 10.1002/mrc.3902

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      The relative configuration for the model compound, obtained from 3J-couplings and NOE connectivities, is used for structure verification with residual dipolar couplings (RDCs) measured in two alignment media, poly-γ-benzyl-l-glutamate and stretched polydimethylsiloxane. A comparison of the various approaches of RDC interpretation available with the programs PALES and MSpin is performed.

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