Spin Density Distribution in a Nitroxide Biradical Containing 13C-Enriched Acetylene Groups in the Bridge: DFT Calculations and EPR Investigation

Кокорин, А. И.; Zaripov, R. B.; Gromov, Oleg I.; Суханов, А. А.; Kálai, Tamás; Lamperth, Éva; Hideg, Kálmán

doi:10.1007/s00723-016-0813-5

Cited by 9 publications

(3 citation statements)

References 37 publications

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“…For VIII 43% of the spin density is calculated to be on the nitrogen of the NO moiety . ENDOR has been used to measure the 0.48 MHz hyperfine coupling to the isotopically enriched 13 C in the bridge of IX in toluene at 80 K. DFT calculations with various models and PBE0 functionals found values of the hyperfine coupling ranging from 0.33 to 0.52 MHz. The best results were obtained with PBE0/N07D or PBE0/EPR‐II.…”

Section: Epr Spectra Of Dinitroxidesmentioning

confidence: 99%

Continuous wave electron paramagnetic resonance of nitroxide biradicals in fluid solution

Eaton

Woodcock

2018

Concepts Magnetic Resonance

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Nitroxide biradicals have been prepared with electron-electron spin-spin exchange interaction, J, ranging from weak to very strong. EPR spectra of these biradicals in fluid solution depend on the ratio of J to the nitrogen hyperfine coupling, AN, and the rates of interconversion between conformations with different values of J. For relatively rigid biradicals EPR spectra can be simulated as the superposition of AB splitting patterns arising from different combinations of nitrogen nuclear spin states. For more flexible biradicals spectra can be simulated with a Liouville representation of the dynamics that interconvert conformations with different values of J on the EPR timescale. Analysis of spectra, factors that impact J, and examples of applications to chemical and biophysical problems are discussed.

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Section: Epr Spectra Of Dinitroxidesmentioning

confidence: 99%

Continuous wave electron paramagnetic resonance of nitroxide biradicals in fluid solution

Eaton

Woodcock

2018

Concepts Magnetic Resonance

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“…Second, to rationalize the plots in Figures –, let us consider the calculated data for HFCCs and spin–spin couplings (with carbon C1) for different carbons presented in Figure . We would like to note here that even the long-range HFCCs shown on Figure should be within the reach of modern EPR (see for example, refs and ). It is clear that for long-range HFCC and spin–spin couplings (via 4 and more bonds) there are very systematic trends (alternation of the sign and monotonous change of the magnitude) for both couplings and the correlation between them.…”

Section: Resultsmentioning

confidence: 92%

Visualization of Electron Paramagnetic Resonance Hyperfine Structure Coupling Pathways

2017

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The close relation between the EPR hyperfine coupling constant and NMR indirect spin-spin coupling constant is well-known. For example, the Karplus-type dependence of hyperfine constants on the dihedral angle, originally proposed for NMR spin-spin coupling, is widely used in pNMR studies. In the present work we propose a new tool for visualization of hyperfine coupling pathways based on our experience with visualization of NMR indirect spin-spin couplings. The plotted 3D-function is the difference between the total electron densities when the magnetic moment of the nucleus of interest changes its sign and as such is an observable from the physical point of view. It has been shown that it is proportional to the linear response of the spin density to the nuclear spin (i.e., magnetic moment). In contrast to the widely used visualization of spin density, our new approach depicts only the part of the electron cloud of a molecule that is affected by the interaction of the unpaired electron(s) with the desired nuclear magnetic moment. Because visualization of NMR spin-spin couplings and hyperfine interaction is based on the same ideas and done using similar techniques, it allows a direct comparison of the corresponding pathways for the two phenomena so as to analyze their resemblance and/or dissimilarity.

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“…In the last two decades, transition-metal-catalyzed cross-coupling reactions have proven to be a powerful tool in modifications of vinyl or aryl halide derived stable nitroxide free radicals [10][11][12] including Heck-, Sonogashira-, and Suzuki-type cross-coupling reactions. In our laboratory, we used these reactions to introduce new substituents onto the pyrroline or tetrahydropyridine ring and to construct nitroxide-condensed heterocycles as well [13,14].…”

Section: Introductionmentioning

confidence: 99%

N-Vinylation of Imidazole and Benzimidazole with a Paramagnetic Vinyl Bromide

Úr

Fekete

Hideg

et al. 2018

Molbank

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An N-vinylation of imidazole and benzimidazole with a paramagnetic vinyl bromide was investigated. Among the tested procedures, Pd-catalyzed reaction was the most powerful one. The N-vinylation of 2-aminobenzimidazole with a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde offered 1,1,3,3-tetramethyl-1H-benzimidazo[1,2-a]pyrrolo[3,4-e]pyrimidin-2(3H)-yloxyl radical and the corresponding non-cyclized Schiff base. The reaction of a β-bromo-α,β-unsaturated pyrroline nitroxide aldehyde with imidazole gave β-imidazo-α,β-unsaturated pyrroline nitroxide aldehyde, which was reduced to the alcohol and converted to an unstable allyl chloride.

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Spin Density Distribution in a Nitroxide Biradical Containing 13C-Enriched Acetylene Groups in the Bridge: DFT Calculations and EPR Investigation

Cited by 9 publications

References 37 publications

Continuous wave electron paramagnetic resonance of nitroxide biradicals in fluid solution

Continuous wave electron paramagnetic resonance of nitroxide biradicals in fluid solution

Visualization of Electron Paramagnetic Resonance Hyperfine Structure Coupling Pathways

N-Vinylation of Imidazole and Benzimidazole with a Paramagnetic Vinyl Bromide

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