Free radical induced contact shift studies. 12. Stable free radicals as NMR spin probe for studying intermolecular interactions. 12. Carbon-13 contact shifts and electron spin delocalization induced by charge transfer interaction between halogenated molecules and stable free radicals

1976 ◽  
Vol 98 (13) ◽  
pp. 3808-3814 ◽  
Author(s):  
Isao Morishima ◽  
Toshiro Inubushi ◽  
Teijiro Yonezawa
Keyword(s):  
Free Radicals ◽  
Charge Transfer ◽  
Free Radical ◽  
Intermolecular Interactions ◽  
Electron Spin ◽  
Spin Probe ◽  
Charge Transfer Interaction ◽  
Contact Shift ◽  
Spin Delocalization ◽  
Stable Free Radicals

Quantitative Electron Paramagnetic Resonance: The Importance of Matching the Q-Factor of Standards and Samples

2001 ◽  
Vol 55 (10) ◽  
pp. 1375-1381 ◽  
Author(s):  
Richard L. Blakley ◽  
Dwight D. Henry ◽  
Walter T. Morgan ◽  
William L. Clapp ◽  
Carr J. Smith ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radicals ◽  
Free Radical ◽  
Spin Trapping ◽  
Microwave Energy ◽  
Q Factor ◽  
Paramagnetic Resonance ◽  
Tert Butyl ◽  
Electron Paramagnetic ◽  
Stable Free Radicals

Electron paramagnetic resonance (EPR) quantification of free radicals from different samples facilitates comparison of free radical concentrations. Stable free radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), in a suitable solvent (e.g., benzene) can be used as a quantification standard. Free radicals found in samples can be shorter lived than radicals in prepared standards and require stabilizing spin-trapping agents such as N-tert-butyl-α-phenylnitrone (PBN) in an appropriate solvent (e.g., benzene). Analysis in our laboratory showed that free radicals from spin-trapped samples quantified against a standard of TEMPO in benzene displayed large differences among identical samples measured on either a Micro-Now 8300, Micro-Now 8400, or Bruker EMX EPR instrument. The Bruker instrument reported that the typical TEMPO in benzene standard had a Q-factor of ∼4400 while the Q-factor of our PBN-containing samples was ∼2500. (The Q-factor is inversely proportional to the amount of dissipated microwave energy in an EPR cavity.) By placing the TEMPO standard in a PBN/benzene solvent matrix we were able to match the Q-factor of our standards and samples, resulting in each of the three EPR instruments giving the same quantified free radical yields for the samples. This result points out the importance of matching the Q-factor between samples and standards for any quantitative EPR measurement.

scholarly journals Studies on Stable Free Radicals. V Reactivity of a Stable Free Radical, 2,2,6,6-Tetramethyl-4-oxopiperidine-1-oxyl

1971 ◽  
Vol 44 (8) ◽  
pp. 2207-2210 ◽  
Author(s):  
Takao Yoshioka ◽  
Susumu Higashida ◽  
Syoji Morimura ◽  
Keisuke Murayama
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Stable Free Radical ◽  
Stable Free Radicals

Metalated Porphyrin Stable Free Radicals: Exploration of Electron Spin Communication and Dynamics

2020 ◽  
Vol 124 (30) ◽  
pp. 6168-6176
Author(s):  
Norbert Grzegorzek ◽  
Haochuan Mao ◽  
Patrick Michel ◽  
Marc J. Junge ◽  
Emmaline R. Lorenzo ◽  
...  
Keyword(s):  
Free Radicals ◽  
Electron Spin ◽  
Stable Free Radicals
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