Alkoxy radical, RCH/sub 2/O, as a free radical product in x-irradiated single crystals of nucleosides and nucleotides

Journal Article · Mon Aug 01 04:00:00 EDT 1977 · J. Chem. Phys.; (United States)

OSTI ID:7143473

Bernhard, W A; Close, D M; Huettermann, J; Zehner, H

The RCH/sub 2/O radical is formed in x-irradiated 3'-cytidylic acid (3'CMP), 5-chlorodeoxyuridine (ClUdR), 5-bromodeoxyuridine (BUdR), adenosinexHCl (ARxHCl), and deoxyadenosine monohydrate (AdRxH/sub 2/O) owing to the net loss of hydrogen from O/sub 5//sub prime/ of the primary hydroxylic group. ESR measurements were made between 78 and 100 K on single crystals of 3'CMP, ClUdR, BUdR, and ARxHCl and on polycrystalline AdRxH/sub 2/O. The range of principal g values is g/sub max/=2.054--2.093, g/sub int/=2.005--2.009, g/sub min/ =1.995--2.000. The range of sum of the isotropic ..beta..-hydrogen hyperfine couplings is A/sup ..beta..//sup 1//sub iso/ +A/sup ..beta..//sup 2//sub iso/=141--156 G. The g tensors and A/sup ..beta..//sub iso/ values are used to determine which oxygen nonbonding orbital contains the bulk of the unpaired electron density. The unpaired electron 2p orbital symmetry axis is perpendicular to a plane determined by X(H) xxxO--C. Of the two relevant hydrogen bonds in the undamaged molecule, the X--HxxxO bond remains intact whereas the hydrogen in the O--HxxxY bond is displaced. The equation A/sup ..beta..//sub iso/=B/sub 0/+B/sub 2/ cos/sup 2/theta, with B/sub 0/ =0 and B/sub 2/=101 +- 13 G describes the dependency of the ..beta..-hydrogen hyperfine coupling on the torsion angle theta, between the unpaired electron symmetry axis and the C--H/sub ..beta../ bond of the RCH/sub 2/O radical. Mechanisms of formation, factors in stabilization, and reactions of decay are discussed.

• Research Organization: Department of Radiation Biology and Biophysics, School of Medicine and Dentistry, The University of Rochester, Rochester, New York 14642
• OSTI ID: 7143473
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 67:3; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ALKOXY RADICALS
CHEMISTRY
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
IONIZING RADIATIONS
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
RADIATION CHEMISTRY
RADIATIONS
RADICALS
RESONANCE
RIBOSIDES
X RADIATION