© John Wiley & Sons, Ltd.
Volume 51, Issue 4
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
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.
Laurence Carlton, Lebohang V. Mokoena and Manuel A. Fernandes
Article first published online: 13 FEB 2013 | DOI: 10.1002/mrc.3925
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.
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
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.
Gregory Helms and James D. Satterlee
Article first published online: 10 FEB 2013 | DOI: 10.1002/mrc.3929
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.
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
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.
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
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.
G.N. Manjunatha Reddy and S. Caldarelli
Article first published online: 20 FEB 2013 | DOI: 10.1002/mrc.3938
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.
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
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.
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
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.