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

Abstract

Throughout this manuscript X¡ will denote the anion mole fraction of the CIO¡-1 ~anion. X(02) is the moles of 02 produced per mole of CIO4present Initially. X(Ag+) is the cation mole fraction of Ag+. A superscript zero will denote a value at time f = 0.

Interaction between copper(II)-arginine complexes and HO2/O2- radicals, a pulse radiolysis study

“…The formation of a Cu02H2+ complex and/or a dinuclear derivative has been postulated previously.24"30 In particular, evidence for its formation has been given, indirectly in pr studies28 and in ESR studies. 29 In the ESR study, values of K6 = 5 X 107 M"1 and kl7 = 3 X 101 M"1 s"1 were published. The value of K6 is, as they discussed, easily reconciled with our and Rabani's measured K6 as, at these concentrations of Cuaq2+, the equilibrium is shifted completely to the right.…”

Autoxidation of transition-metal complexes. Reaction of a 1:1 cobalt-molecular oxygen complex with acids to yield hydrogen peroxide. Kinetics and mechanism

“…Short-lived hydroperoxyl radicals complexes analogous to Com(-02H) are known for transition metals in high oxidation states including Cu(II), Ti(IV), Zr(IV), Ce(lll), and Mo(Vl) that have been observed by ESR upon mixing of the metal ion with photolytically or chemically generated H02• in a flow system. 54 The equilibrium constants for + H02• M(H02•) are generally high (>103 M-1).…”

Superoxide Radical Anion Adduct of 5,5-Dimethyl-1-pyrroline N-Oxide (DMPO). 1. The Thermodynamics of Formation and Its Acidity

“…3 Prior to 1974, 4 the hydroperoxyl radical ( • O 2 H) could only be detected directly by EPR at low temperature 5 or as a metal complex. 6,7 These approaches to radical detection limited the detection of superoxide (O 2 •-) in biological systems, until DMPO was introduced for this purpose almost 3 decades ago by Harbor et al 4 Subsequent detection of superoxide/hydroperoxyl (O 2 •-/ • O 2 H) radicals in aqueous systems by EPR spin trapping using DMPO paved the way to exciting new findings in chemistry [8][9][10][11][12] and biology. [13][14][15][16][17][18][19] Although DMPO is still widely employed as a spin trap, it has major drawbacks which limit the spectral interpretation of its adducts with O 2 •-/ • O 2 H. [20][21][22] Several DMPO-type analogues have been developed over the years to overcome the limitation of DMPO.…”