Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Cutsail, George E.

doi:10.1039/d0dt02436h

Cited by 34 publications

(34 citation statements)

References 52 publications

(67 reference statements)

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“…Nonetheless, the significant shifts from g e are in line with increased SOC for heavier elements and supporting of a bismuth-centred radical. 28 Simulations (Fig. S17 † ) allow for estimates of a maximum Bi hyperfine coupling of 700 MHz.…”

Section: Resultsmentioning

confidence: 99%

“…The large g-shi observed from g e is the result of a large spin-orbit contribution (SOC) of the unpaired electron, supporting that the radical is metal-centred at the antimony atom(s). 28 The CW X-band EPR spectrum of the frozen solution (Fig. 5) shows a broad signal with broad hyperne features, due to the coupling of the unpaired electron with two Sb atoms.…”

Section: Epr Spectroscopymentioning

confidence: 99%

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Synthesis, structure and bonding nature of heavy dipnictene radical anions

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Section: Epr Spectroscopymentioning

confidence: 99%

Synthesis, structure and bonding nature of heavy dipnictene radical anions

et al. 2021

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“…The large g-anisotropy observed for [L(Cl)GaBi( Me cAAC)] •+ and [L(X)Ga]2Bi • is not unlike that observed for the lighter Sb analogues, however, the low g3 value is unprecedented for a Bi radical and more broadly, Group 15 radicals. 10 The hyperfine of [L(Cl)GaBi( Me cAAC)] •+ and [L(X)Ga]2Bi • is significantly smaller than that observed for [O(SiMe2NAr)2]Bi • . 8 It may be reasoned that the electropositive Ga ligands facilitate increased electron delocalization compared to the [O(SiMe2NAr)2] ligand, that coordinates via the lighter and more electronegative nitrogen atoms.…”

Section: Resultsmentioning

confidence: 87%

“…Due to their paramagnetic nature, electron paramagnetic resonance (EPR) spectroscopy plays a central role in the characterization of bismuth radicals. 10 For bismuth, a single nuclear active isotope, 209 Bi, occurs at 100% natural abundance with a nuclear spin of I = 9/2. To date, very few examples of stable bismuth radicals exist and the complete electron paramagnetic characterization of their hyperfine interaction is often challenging.…”

Section: Introductionmentioning

confidence: 99%

X-band Parallel-Mode and Multifrequency Electron Paramagnetic Resonance Spectroscopy of S = 1/2 Bismuth Centers

Haak

Krüger

Abrosimov

et al. 2022

Preprint

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The recent successes in the isolation and characterization of several bismuth radicals inspire the development of new spectroscopic approaches for the in-depth analysis of their electronic structure. Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for the characterization of main group radicals. However, the large electron-nuclear hyperfine interactions of Bi (209Bi, I = 9/2) have presented difficult challenges to fully interpret the spectral properties for some of these radicals. Parallel-mode EPR (B1 || B0) is almost exclusively employed for the study of S > 1/2 systems but becomes feasible for S = 1/2 systems with large hyperfine couplings, offering a distinct EPR spectroscopic method. Herein, we demonstrate the application of conventional X-band parallel-mode EPR for S = 1/2, I = 9/2 spin systems: Bi doped crystalline silicon (Bi:Si) and the molecular Bi radicals: [L(X)Ga]2Bi• (X = Cl, I) and [L(Cl)GaBi(MecAAC)]• (L = HC[MeCN(2,6-iPr2C6H3)]2). In combination with multifrequency perpendicular-mode EPR (X-, Q-, and W-band frequency), we were able to fully refine both of the anisotropic g- and A-tensors of these molecular radicals. The parallel-mode EPR experiments demonstrated and discussed here have the potential to enable the characterization of other S = 1/2 systems with large hyperfine couplings, which is often challenging by conventional perpendicular-mode EPR techniques. Considerations pertaining to the choice of microwave frequency are discussed for relevant spin-systems.

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“…As the antiradical activity of the N-oxide surfactants could have been low, the decay of GO• and DPPH• in the presence of the di- and mono-N-oxide surfactants was monitored with electron paramagnetic resonance (EPR) spectroscopy, which is an extremely sensitive technique for the radical systems [ 25 , 26 , 27 ]. DPPH• and GO• have well-defined EPR spectra, and a clear decrease in their intensity was observed for the N-oxide surfactants as exemplified by C 12 (DAPANO) 2 in Figure 3 .…”

Section: Resultsmentioning

confidence: 99%

Antiradical Properties of N-Oxide Surfactants—Two in One

Lewińska

Kulbacka

Domżał-Kędzia

et al. 2021

IJMS

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Surfactants are molecules that lower surface or interfacial tension, and thus they are broadly used as detergents, wetting agents, emulsifiers, foaming agents, or dispersants. However, for modern applications, substances that can perform more than one function are desired. In this study we evaluated antioxidant properties of two homological series of N-oxide surfactants: monocephalic 3-(alkanoylamino)propyldimethylamine-N-oxides and dicephalic N,N-bis[3 ,3′-(dimethylamino)propyl]alkylamide di-N-oxides. Their antiradical properties were tested against stable radicals using electron paramagnetic resonance (EPR) and UV-vis spectroscopy. The experimental investigation was supported by theoretical density functional theory (DFT) and ab initio modeling of the X–H bonds dissociation enthalpies, ionization potentials, and Gibbs free energies for radical scavenging reactions. The evaluation was supplemented with a study of biological activity. We found that the mono- and di-N-oxides are capable of scavenging reactive radicals; however, the dicephalic surfactants are more efficient than their linear analogues.

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Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Abstract: The exploration of heavy main-group radicals is rapidly expanding, for which electron paramagnetic resonance (EPR) spectroscopic characterisation plays a key role. EPR spectroscopy has the capacity to deliver information of...

Cited by 34 publications

References 52 publications

Synthesis, structure and bonding nature of heavy dipnictene radical anions

Synthesis, structure and bonding nature of heavy dipnictene radical anions

X-band Parallel-Mode and Multifrequency Electron Paramagnetic Resonance Spectroscopy of S = 1/2 Bismuth Centers

Antiradical Properties of N-Oxide Surfactants—Two in One

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