ESR Study of a Complex Formation Between HO₂ Radical and Peroxy‐Vanadium (V) Ion

Abstract

A8STRACTH0 2 radicals were generated in a flow system by the reaction: Ce 4+ +HP2-> Ce s+ + H0 2 +H+. The H0 2 radicals were mixed with V -HP2 solutions and ESR spectroscopy was used to follow the reaction. It was shown that H0 2 reacts with both VO(02)+ and VO(02}2 complexes. The ESR signal of the complexed radical consists of eight lines, indicating that the unpaired electron interacts with the Vanadium nucleus. The kinetics of the formation and decay reactions of the complexed radical were studied.

Hydroperoxyl radical reactions. II. Cupric ions in modulated photolysis. Electron paramagnetic resonance experiments

“…In this experiment, about 5 µ of [Th-H02-]4+ were produced by momentarily subjecting the solution to the light with the use of the shutter. The decay rate and the order of the reaction were in accordance with the decay of TI1-HO2• produced using the flow technique, in which HO2• is produced via the reaction of Ce(IV) and H2O2.10b This decay was attributed to the recombination reactions HO* + ho2; -HA + 02 (7) [Th-H0.2':]4+ + HO/ -* Th(IV) + HA + 02 (8) [Thl-HOJ4+ + [Th-HO/"4* -* 2|Th(IV!) + HA + 02 (9) Addition of minute amounts of Cu2+ (2 or 3 µ ) to these solutions increased the decay rate of Th-HÜ2 • by a factor of ~20.…”

Abnormal Broadening of Free Radical EPR Lines: A New Test Probe for Singlet Dioxygen in Solution

“…An octet with g = 2.011 25 ± 0.000 05 G and a V = 0.000 44 cm -1 parameters coinciding with those for the known vanadium complex 3 − was detected in system A in the course of the H 2 O 2 decomposition. − The strong and well-resolved octet of 3 was only observed when the EPR cell was purged with Ar or CO 2 . Under 3 O 2 flow, the lines of the octet were broadened up to ca.…”

Detection of Oxygen Radicals in Biological Reactions

“…(3) Czapski (personal communication) suggests the use of the complex formation of HOj/O; with transition metals (Samuni and Czapski, 1970 ; Meisel et a/., 1974). Such complexes are stable enough to allow kinetic studies by EPR spectroscopy.…”