Magnetic Resonance in Chemistry

Cover image for Vol. 51 Issue 10

October 2013

Volume 51, Issue 10

Pages 605–681

  1. Research Articles

    1. Top of page
    2. Research Articles
    1. Additional insights from very-high-resolution 13C NMR spectra of long-chain n-alkanes (pages 605–613)

      Lawrence B. Alemany

      Version of Record online: 25 JUL 2013 | DOI: 10.1002/mrc.3988

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      Resolving up to ten signals in the 13C spectra of long n-alkanes enables more detailed analysis of segmental motion. A detailed understanding of the extreme overlap of the C-10 and C-11 signals in n-C21H44 and n-C22H46 remains to be obtained; conformational effects may be involved. Significant spectral differences for the interior carbons are observed in C6D6 or C6D5CD3 compared to CDCl3; spectra for the interior carbons of some odd-number alkanes in CDCl3 significantly differ from their even-number counterparts.

    2. Study of the EFG tensor at 75As nuclei in Ge-As-Se chalcogenide glasses (pages 614–620)

      O. N. Bolebrukh, N. Ya. Sinyavsky, B. Dobosz, I. P. Korneva, R. Krzyminiewski, M. Ostafin and B. Nogaj

      Version of Record online: 7 AUG 2013 | DOI: 10.1002/mrc.3990

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      Asymmetry parameters of the electric field gradient tensor at 75As nuclei were determined for chalcogenide glassy semiconductors of the Ge-As-Se system by comparing the experimental and simulated 75As nuclear quadrupole resonance nutation interferograms. A comparison was made between the results of the analysis of the Ge-As-Se system by nuclear quadrupole resonance and electron paramagnetic resonance methods, and this allowed us to make supposition that a structural phase transition occurs at inline image = 2.4 from two-dimensional to three-dimensional chalcogenide glassy semiconductors structure.

    3. 13C NMR spectroscopy of copoly(arylenephthalide) derivatives with diphenyloxide and terphenyl fragments in the main chain (pages 621–629)

      Vladimir A. Kraikin, Akhnef A. Fatykhov, Il'nara I. Sakhipova, Elvira A. Sedova, Aleksandr E. Egorov and Sergey N. Salazkin

      Version of Record online: 6 AUG 2013 | DOI: 10.1002/mrc.3991

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      Full and unequivocally assignments of chemically similar carbons of the inner and end homodiad and heterodiad have been carried out. This enabled us to create additivity parameters that facilitate an analysis of a chemical structure of high-molecular copoly(arylenephthalide) compounds.

    4. Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles (pages 630–635)

      Klaudia Radula-Janik, Teobald Kupka, Krzysztof Ejsmont, Zdzislaw Daszkiewicz and Stephan P. A. Sauer

      Version of Record online: 6 AUG 2013 | DOI: 10.1002/mrc.3992

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      The assignment of the density functional theory calculated 13C NMR chemical shifts and the impact of halogen electronegativity on selected 3,6-dihalogeno-N-alkyl carbazole derivatives is reported. The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N-alkylcarbazoles.

    5. Changes in the NMR characteristics of 3,6-di-tert-butylquinone on formation of paramagnetic complexes (pages 636–640)

      Vladimir K. Voronov, Igor А. Ushakov, Dmitrii S. Grishmanovskii and Vladimir K. Cherkasov

      Version of Record online: 12 AUG 2013 | DOI: 10.1002/mrc.3993

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      The 1H and 13C NMR spectra of 3,6-ditertbutylquinone recorded in a wide range of temperatures have been analyzed. The spectra are transformed by paramagnetic additives of Co, Ni and Cu semiquinone complexes. It is shown that the observed average parameters of experimental spectra are caused by the involvement of 3,6-ditertbutylquinone molecules in an exchange between the coordination sphere of paramagnetic ion and free ligand.

    6. A multidimensional approach to the analysis of chemical shift titration experiments in the frame of a multiple reaction scheme (pages 641–648)

      Anthony D'Aléo, Elise Dumont, Olivier Maury and Nicolas Giraud

      Version of Record online: 16 AUG 2013 | DOI: 10.1002/mrc.3994

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      A method for fitting curves acquired by chemical shift titration experiments, in the frame of a three-step complexation mechanism, is presented. It determines the best fitting curve and provides distributions for the different parameters of the complexation model that are compatible with the experimental precision. This protocol is applied to the study of the supramolecular interactions, in aqueous solution, between a lanthanide complex and three different model molecules.

    7. Automatic assignment of 1H-NMR spectra of small molecules (pages 649–654)

      C. Cobas, F. Seoane, E. Vaz, M. A. Bernstein, S. Dominguez, M. Pérez and S. Sýkora

      Version of Record online: 23 AUG 2013 | DOI: 10.1002/mrc.3995

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      A novel data-evaluation procedure for the automatic atom to peak or multiplet assignment of 1H-NMR spectra of small molecules has been developed using a fast and robust expert system that has a high level of success. Feedback is provided to the user on the confidence in the assignments for making an overall desirable and useful software functionality.

    8. Determination of glucan phosphorylation using heteronuclear 1H,13C double and 1H,13C,31P triple-resonance NMR spectra (pages 655–661)

      Peter Schmieder, Felix Nitschke, Martin Steup, Keven Mallow and Edgar Specker

      Version of Record online: 4 AUG 2013 | DOI: 10.1002/mrc.3996

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      Heteronuclear 1H,13C and 1H,13C,31P techniques in combination with information derived from spectra of a set of reference compounds are used to unambiguously determine the phosphorylation sites in starch and glycogen even with heterogeneous samples from natural source.

    9. Complexation of rhodium(II) tetracarboxylates with aliphatic diamines in solution: 1H and 13C NMR and DFT investigations (pages 662–670)

      Jarosław Jaźwiński and Agnieszka Sadlej

      Version of Record online: 13 AUG 2013 | DOI: 10.1002/mrc.3997

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      The complexation of rhodium(II) tetraacetate, tetrakistrifluoroacetate and tetrakisoctanoate with a set of diamines (ethane-1,2-diamine, propane-1,3-diamine and nonane-1,9-diamine) and their N,N′-dimethyl and N,N,N′,N′-tetramethyl derivatives in chloroform solution has been investigated by means of 1H and 13C NMR measurements and density functional theory (DFT) modelling. Depending on the kind of diamine and rhodium salt, various adducts, axial (secondary and tertiary diamines) and equatorial (primary diamines), were formed.

    10. Identification of radiation-induced radical structure in azocalix[4]arene: an EPR study (pages 671–675)

      Keziban Usta, Ozlem Ozen Karakus, Ayhan Usta and Hasalettin Deligoz

      Version of Record online: 16 AUG 2013 | DOI: 10.1002/mrc.3998

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      Radical structure occurred by scission of a methylene C-H bond of a terminal ethyl group because of ionizing radiation, and the unpaired electron was localized on carbon proton (Ca) in the ester moiety of the sample, and the other moiety of the azocalix[4]arene sample in the study does not contribute to the radical induction at all.

    11. Modeling 21Ne NMR parameters for carbon nanosystems (pages 676–681)

      Teobald Kupka, Marzena Nieradka, Jakub Kaminský and Leszek Stobiński

      Version of Record online: 23 AUG 2013 | DOI: 10.1002/mrc.3999

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      The impact of confinement on neon used as an NMR probe placed inside selected fullerene cages was studied. High sensitivity toward the proximity of multiple CC bonds in C2H2, C2H4, C5H6 and inside C28, C30, C32, C34 and C60 fullerenes was predicted from changes of 21Ne NMR parameters.

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