Magnetic resonance parameters and structure of substituted stannyloxyphenoxyl radicals: Investigation by means of ESR in the 2-mm band

Structural Examination of the Transient 3-Aminotyrosyl Radical on the PCET Pathway of E. coli Ribonucleotide Reductase by Multifrequency EPR Spectroscopy

“…The g values, g x = 2.00520, g y = 2.00420, g z = 2.00220, have been resolved using 180 GHz pulsed EPR spectroscopy and are in the range of those previously reported for phenoxy and ortho-substituted phenoxy radicals. 72 − 77 Comparison of the g values of NH 2 Y 730 • with those for Y 122 • ( g x = 2.0091, g y = 2.0046, g z = 2.0023 for Y 122 •) 46 reveal that g y and g z are similar and that the g x shift is significantly suppressed.…”

“…The first is ortho substitution of the phenoxy ring with a heteroatom such as O or S, and the second is H-bonding to the phenoxy radical oxygen. 54 , 72 − 75 , 77 High-frequency EPR studies on phenoxy radicals substituted at the ortho position with a thio-ether group such as that found in galactose oxidase have revealed a g x value of 2.007 with axial g tensor symmetry. 75 , 77 For o -hydroxyphenoxyl radicals coordinated to a metal, the g x values varied between 2.0045 and 2.006, 72 and in our recent studies with Y 356 DOPA-β2, 24 , 78 a g x value of 2.0056 with an axial g tensor was observed upon formation of the DOPA• (M. Bennati and J. Stubbe, unpublished results).…”

Chemical and radiation-chemical radical reactions in lignocellulose materials

“…The main values of g-tensor-g x ¼2.00558, g y ¼2.00520, and g z ¼2.00232-are close to those of quinine-type radicals. Since the anisotropy of g is below 0.001 (Dg¼ g xg y ¼0.0003874 Â 10 À 5 o0.001), spectrum 9 can be attributed to osemiquinone ion-radicals (Brezgunov et al, 1992). Therefore, the reaction of lignin with NaOH yields pyrocatechol radical anions:…”