EFFECT OF COPPER(II) IONS ON THE STABILITY OF SPIN ADDUCTS FORMED BY THE REACTION OF 5,5-DIMETHYLPYRROLINE-N-OXIDE WITH HYDROXYL AND HYDROXYLALKYL RADICALS

The reactions of copper(II) species with spin adducts formed by reaction of OH, CH3CHOH or (CH3)2COH with DMPO (5,5-dimethylpyrroline-N-oxide) have been investigated. The spin adducts prepared by gamma-irradiation of appropriate solutions were detected using esr. Copper(II) in the form of aqua, phen, or gamma-alanine complexes reacted rapidly with the OH adduct to give products that gave no esr signal, but with the hydroxylalkyl adducts, reacted to give a new 9-line esr signal, identified as due to the H- adduct, (DMPO-H.). Measurement of the yield of Cu(phen)+ formed by reaction of the copper(II) complex with the spin adduct showed that approximately 25% of the radiation-produced radicals formed esr detectable spin adducts. The implications of these findings for the use of spin trapping to detect radical intermediates in biological systems is discussed.