Electron Spin Resonance Spectroscopy Studies on Reduction Process of Nitroxyl Radicals used in Molecular Imaging

Dhas, M. Kumara; Jawahar, Ajay; Benial, A. Milton Franklin

doi:10.11648/j.ejb.20140201.11

Cited by 2 publications

(2 citation statements)

References 38 publications

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“…We will close the computational experiments revisiting the parameters that are related with the EPR spectroscopy touching the problem of the hyperfine coupling [38,76,77]. For a general case of a set of nuclei, with components labelled by i , having each the electronic spin S i and the I i nuclear spins, the isotropic coupling is described by the A i parameters and the following phenomenological Hamiltonian: H^Hyp=∑iAiS^i⋅I^i…”

Section: Resultsmentioning

confidence: 99%

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Molecular and Supramolecular Interactions in Systems with Nitroxide-Based Radicals

Buta¹,

Toader²,

Frecuş³

et al. 2019

IJMS

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Nitroxide-based radicals, having the advantage of firm chemical stability, are usable as probes in the detection of nanoscale details in the chemical environment of various multi-component systems, based on subtle variations in their electron paramagnetic resonance spectra. We propose a systematic walk through the vast area of problems and inquires that are implied by the rationalization of solvent effects on the spectral parameters, by first-principle methods of structural chemistry. Our approach consists of using state-of-the-art procedures, like Density Functional Theory (DFT), on properly designed systems, kept at the border of idealization and chemical realism. Thus, we investigate the case of real solvent molecules intervening in different configurations between two radical molecules, in comparison with radicals taken in vacuum or having the solvent that is treated by surrogate models, such as polarization continuum approximation. In this work, we selected the dichloromethane as solvent and the prototype radicals abbreviated TEMPO ((2,2,6,6-Tetramethylpiperidin-1-yl) oxyl). In another branch of the work, we check the interaction of radicals with large toroidal molecules, β-cyclodextrin, and cucurbit[6]uril, modeling the interaction energy profile at encapsulation. The drawn synoptic view offers valuable rationales for understanding spectroscopy and energetics of nitroxide radicals in various environments, which are specific to soft chemistry.

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Section: Resultsmentioning

confidence: 99%

“…The experimental A parameter for TEMPO is around 50 MHz, e.g., A = 50.7 in the reference [76] or 47.7 MHz in the [77] work. It depends on the solvent and other conditions, but in a somewhat moderate measure, because of the protective fence raised by the four surrounding methyl groups nearby the nitrogen atom.…”

Section: Resultsmentioning

confidence: 99%

Molecular and Supramolecular Interactions in Systems with Nitroxide-Based Radicals

Buta¹,

Toader²,

Frecuş³

et al. 2019

IJMS

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ESR line width and line shape dependence of Overhauser-enhanced magnetic resonance imaging

Meenakumari¹,

Utsumi

Jawahar³

et al. 2016

Magn. Reson. Chem.

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Electron spin resonance and Overhauser-enhanced magnetic resonance imaging studies were carried out for various concentrations of N-labeled 3-carbamoyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl in pure water. Overhauser-enhancement factor attains maxima in the range of 2.5-3 mm concentration. The leakage factor showed an asymptotic increase with increasing agent concentration. The coupling parameter showed the interaction between the electron and nuclear spins to be mainly dipolar in origin. The electron spin resonance parameters, such as the line width, line shape and g-factor, were determined. The line width analysis confirms that the line broadening is proportional to the agent concentration, and also the agent concentration is optimized in the range of 2.5-3 mm. The line shape analysis shows that the observed electron spin resonance line shape is a Voigt line shape, in which the Lorentzian component is dominant. The contribution of Lorentzian component was estimated using the winsim package. The Lorentzian component of the resonance line attains maxima in the range of 2.5-3 mm concentration. Therefore, this study reveals that the agent concentration, line width and Lorentzian component are the important factors in determining the Overhauser-enhancement factor. Hence, the agent concentration was optimized as 2.5-3 mm for in vivo/in vitro electron spin resonance imaging and Overhauser-enhanced magnetic resonance imaging phantom studies. Copyright © 2016 John Wiley& Sons, Ltd.

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Electron Spin Resonance Spectroscopy Studies on Reduction Process of Nitroxyl Radicals used in Molecular Imaging

Cited by 2 publications

References 38 publications

Molecular and Supramolecular Interactions in Systems with Nitroxide-Based Radicals

Molecular and Supramolecular Interactions in Systems with Nitroxide-Based Radicals

ESR line width and line shape dependence of Overhauser-enhanced magnetic resonance imaging

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