Magnetic Resonance in Chemistry

Cover image for Vol. 51 Issue 4

April 2013

Volume 51, Issue 4

Pages 193–254

  1. Rapid Communication

    1. Top of page
    2. Rapid Communication
    3. Research Articles
    4. MRC Letters
    1. Stability of H-complexes of nicotinamide nitrogen heteroatom with water and ethanol in mixed solvents by 13C NMR probing (pages 193–198)

      V. A. Sharnin, V. V. Aleksandriysky, S. V. Dushina and G. A. Gamov

      Article first published online: 19 FEB 2013 | DOI: 10.1002/mrc.3934

      Thumbnail image of graphical abstract

      We determined the stability constants of H-complexes of nicotinamide nitrogen heteroatom with water and ethanol from 13C NMR data. The transfer Gibbs energy of this heteroatom was found. The NMR manifestations of nicotinamide solvation state change were observed and discussed.

  2. Research Articles

    1. Top of page
    2. Rapid Communication
    3. Research Articles
    4. MRC Letters
    1. Tungsten-183 NMR study of cis-[W(CO)4(PPh3)(4-RC5H4N)]; effect of varying the σ donor strength of the pyridine (pages 199–202)

      Laurence Carlton, Lebohang V. Mokoena and Manuel A. Fernandes

      Article first published online: 13 FEB 2013 | DOI: 10.1002/mrc.3925

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      Tungsten-183 chemical shifts for complexes with R = H, Me, Ph, COMe, COPh, OMe, NMe2, Cl, NO2 show a good correlation with Hammett σp for R.

    2. The structure of azines derived from C-formyl-1H-imidazoles in solution and in the solid state: tautomerism, configurational and conformational studies (pages 203–221)

      Joana Pinto, Vera L. M. Silva, Artur M. S. Silva, Rosa M. Claramunt, Dionisia Sanz, M. Carmen Torralba, M. Rosario Torres, Felipe Reviriego, Ibon Alkorta and José Elguero

      Article first published online: 7 FEB 2013 | DOI: 10.1002/mrc.3926

      Thumbnail image of graphical abstract

      The structures of three azines derived from 2-formylimidazole, 4(5)-formylimidazole and 4(5)-formyl-5(4)-methylimidazole have been determined in solution and in the solid state by means of DFT theoretical calculations, NMR (solution and CPMAS) and X-ray crystallography.

    3. Keeping PASE with WEFT: SHWEFT–PASE pulse sequences for 1H NMR spectra of highly paramagnetic molecules (pages 222–229)

      Gregory Helms and James D. Satterlee

      Article first published online: 10 FEB 2013 | DOI: 10.1002/mrc.3929

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      A series of simple pulse sequences were constructed by combining the principles of water elimination Fourier transform and paramagnetic spectroscopy employing polychromatic and adiabatic pulses that significantly improve one-dimensional 1H spectral quality for highly paramagnetic molecules. The technique was extended to one-dimensional NOE difference and two-dimensional NOESY experiments.

    4. 29Si–1H IMPACT HMBC: a suitable tool for analyzing silylated derivatives (pages 230–233)

      Jonathan Farjon, Audrey Giros, Sandrine Deloisy, Luis Blanco, Jérôme Hannedouche, Emmanuelle Schulz and Denis Merlet

      Article first published online: 13 FEB 2013 | DOI: 10.1002/mrc.3932

      Thumbnail image of graphical abstract

      In comparison with the standard 29Si–1H heteronuclear multiple bond correlation (HMBC), a gain of 2 in sensitivity has been reached in 30–40 s with a high spectral resolution with the help of the α-optimized 29Si–1H IMPACT HMBC on silylated derivatives.

    5. Molecular dynamics of 6-methyl-2-phenyl-2,3-dihydro-4H-chromen-4-one and 6-methyl-2-(4-nitrophenyl)-2,3-dihydro-4H-chromen-4-one (flavanone) derivatives in a solution studied by NMR spectroscopy (pages 234–239)

      Ibrahim Garib Mamedov, Musa Rza Bayramov, Yegana Vagif Mamedova and Abel Mammadali Maharramov

      Article first published online: 19 FEB 2013 | DOI: 10.1002/mrc.3933

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      Molecular dynamics of benzoxazepin, oxime, pyrazole, thiosemicarbazone derivatives of some flavanones have been investigated in solution using NMR. The results confirm the formation of different O-H···O, O–H···N, N···H–N type intramolecular hydrogen bonds in the pyrazole and oxime molecules. The rotational barrier energy and energy of intramolecular hydrogen bonds have been determined.

    6. Improved excitation uniformity in multiple-quantum NMR experiments of mixtures (pages 240–244)

      G.N. Manjunatha Reddy and S. Caldarelli

      Article first published online: 20 FEB 2013 | DOI: 10.1002/mrc.3938

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      The efficiency of multiple-quantum experiments is highly dependent not only on the spin system details but also on the relaxation properties. This is particularly true in the presence of small couplings. We provide a scheme to produce more homogeneous multiple-quantum spectra for mixtures of aromatic systems using co-addition of multiple excitation delays, chosen according to the spin system characteristics and the observed signal lifetime.

    7. NMR-based conformational analysis of perezone and analogues (pages 245–250)

      L. Gerardo Zepeda, Eleuterio Burgueño-Tapia, Nury Pérez-Hernández, Gabriel Cuevas and Pedro Joseph-Nathan

      Article first published online: 21 FEB 2013 | DOI: 10.1002/mrc.3940

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      Complete assignment of the 1H NMR chemical shift and coupling constant values of perezone (1), O-methylperezone (2) and 6-hydroxyperezone (3) was carried out by using spin–spin simulation. The resulting simulated spectra for the three compounds showed strong similarity to their corresponding experimental spectra, thus revealing that the conformation of these three molecules in solution is indeed almost identical.

  3. MRC Letters

    1. Top of page
    2. Rapid Communication
    3. Research Articles
    4. MRC Letters
    1. Synthesis and NMR studies of novel chromone-2-carboxamide derivatives (pages 251–254)

      Alexandra Gaspar, Fernando Cagide, Elias Quezada, Joana Reis, Eugenio Uriarte and Fernanda Borges

      Article first published online: 14 FEB 2013 | DOI: 10.1002/mrc.3937

      Thumbnail image of graphical abstract

      The synthesis and complete structural characterization using one- and two-dimensional resonance techniques of novel chromone carboxamide derivatives, with electron donating and electron withdrawing substituents, in different positions of the exocyclic ring, is reported.

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