Electron spin resonance studies on deuterated nitroxyl spin probes used in <scp>Overhauser</scp>‐enhanced magnetic resonance imaging

Jebaraj, D. David; Utsumi, Hideo; Benial, A. Milton Franklin

doi:10.1002/mrc.4576

Cited by 3 publications

(2 citation statements)

References 51 publications

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“…Complicated hyperfine structure and line broadening in the EPR spectra of sterically shielded nitroxides makes them inefficient in EPRI and OMRI applications, where radicals with a minimal number of narrow lines are required for better resolution and enhancement. − Broadened spectral lines can also hamper analysis of molecular dynamics using spin labeling and EPR . A better understanding of the factors affecting the hyperfine structure in the EPR spectra of sterically shielded nitroxides could help in the molecular design of better structures.…”

Section: Introductionmentioning

confidence: 99%

Origin of Long-Range Hyperfine Couplings in the EPR Spectra of 2,2,5,5-Tetraethylpyrrolidine-1-oxyls

Polienko,

Dobrynin,

Lomanovich

et al. 2023

ACS Omega

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Cyclic nitroxides with several bulky alkyl substituents adjacent to the nitroxide group are known to demonstrate a much higher stability to bioreduction than their tetramethyl analogues. Among these so-called “sterically shielded” nitroxides, the pyrrolidine derivatives are the most stable. The EPR spectra of some sterically shielded pyrrolidine-1-oxyls were reported to show one or two large additional doublet splittings with a hyperfine coupling (hfc) constant (ca. 0.2–0.4 mT). To determine the origin of these hfc, a series of 2-R-2,5,5-triethyl-3,4-bis(hydroxymethyl)-pyrrolidine-1-oxyls with methylene groups stereospecifically enriched with deuterium were prepared, and their CW EPR spectra were studied. In addition, these nitroxides were investigated using quantum chemical calculations on the UB3LYP/def2-TZVP level and NBO analysis. The apparent constants were assigned to hfc with γ-hydrogen in the side chain, with the contribution of the NBO orbital βπ*(N–O) to the natural localized molecular orbital βσ(C–H) playing the major role. This interaction is efficient if the ethyl substituent is in the pseudoaxial position of the ring and the CH2–CH3 bond is codirected with (parallel to) N–O. The apparent constant a H increases with the Boltzmann population of this conformation.

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Section: Introductionmentioning

confidence: 99%

Origin of Long-Range Hyperfine Couplings in the EPR Spectra of 2,2,5,5-Tetraethylpyrrolidine-1-oxyls

Polienko,

Dobrynin,

Lomanovich

et al. 2023

ACS Omega

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“…synthesized various nitroxyl probes that have a 15 N nucleus and deuterium and measured the enhancement factor for OMRI experiments . Recently, ESR studies were carried out for 14 N‐labeled and 15 N‐labeled carbamoyl‐PROXYL, 3‐carboxy‐2,2,5,5,‐tetramethyl‐pyrrolidin‐1‐oxyl (carboxy‐PROXYL), MC‐PROXYL, and their deuterated nitroxyl radicals . The deuterated nitroxyl spin probes have a small line width due to the lower magnetic moment of deuterium.…”

Section: Introductionmentioning

confidence: 99%

Low‐frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution

Jebaraj

Utsumi

Benial³

2017

Magnetic Reson in Chemistry

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Low-frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as the line width, hyperfine coupling constant, g factor, rotational correlation time, permeability, and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture. The rotational correlation time increases with increasing concentration of corn oil, which indicates the less mobile nature of spin probe in corn oil mixture. The membrane permeability and partition parameter values were estimated as a function of corn oil concentration, which reveals that the nitroxyl radicals permeate equally into the aqueous phase and oil phase at the corn oil concentration of 50%. The electron spin resonance spectra demonstrate the permeable and impermeable nature of nitroxyl spin probes. From these results, the corn oil concentration was optimized as 50% for phantom studies. In this work, the corn oil and pure water mixture phantom models with various viscosities correspond to plasma membrane, and whole blood membrane with different hematocrit levels was studied for monitoring the biological characteristics and their interactions with permeable nitroxyl spin probe. These results will be useful for the development of electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities in biomedical applications.

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Quantum Mimicry With Inorganic Chemistry

Campanella

Üngör

Zadrozny

2023

Comments on Inorganic Chemistry

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Electron spin resonance studies on deuterated nitroxyl spin probes used in Overhauser‐enhanced magnetic resonance imaging

Cited by 3 publications

References 51 publications

Origin of Long-Range Hyperfine Couplings in the EPR Spectra of 2,2,5,5-Tetraethylpyrrolidine-1-oxyls

Origin of Long-Range Hyperfine Couplings in the EPR Spectra of 2,2,5,5-Tetraethylpyrrolidine-1-oxyls

Low‐frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution

Quantum Mimicry With Inorganic Chemistry

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