Riederer, Heinz; Huettermann, Juergen published the artcile< Matrix-isolation of free radicals from 5-halouracils. 3. Electron spin resonance of base oxidation in aqueous acidic glasses>, Computed Properties of 4956-05-2, the main research area is ESR irradiated nucleic acid base; uracil irradiated ESR; halouracil irradiated ESR; thymine irradiated ESR; nucleoside derivative irradiated ESR.
ESR of x-irradiated aqueous acidic glasses (5.3 M H2SO4, 7.2-14.7 M H3PO4) was used to study the base π-cations of the nucleic acid constituents uracil (U), thymine (T), and the range of 5-halouracils (FU, ClU, BU, IU) as well as their nucleoside derivatives, and to follow their secondary reactions. High solute concentrations (>50 mM) and the presence of electron scavengers (100-200 mM Na2S2O8 or H2O2) favored cation formation and stabilization and suppressed the formation of other solute radicals. Generation of the base cations resulted from transfer of a (possibly) excited solvent hole to the pyrimidine base during x-irradation at 77 K and from attack of the trapped solvent hole (SO4-: or HPO4-:) after thermal activation at 145-65 K. The base cations were either deprotonated at N1, as in most of the free bases, or added OH- at C6 in the nucleosides, where the deoxyribose moiety prevented deprotonation. This hydroxylation was suppressed in a water-deficient system (e.g., 14.7 M H3PO4) but very efficient in 5.3 M H2SO4. The structures of both the primary and secondary radicals were confirmed in most cases by a complete simulation of the exptl. ESR powder spectra. The ESR parameters obtained display a strong influence of the 5 substituent (i.e., the halogens) on the spin-d. distribution in the radicals. Characteristic for the π cations was the high spin d. in the halogen π orbital, ranging from 8% in FU to 40% in IU. Moreover, the amount of H2O in the environment exerts a considerable influence on the halogen spin densities in the charged cation.
Journal of Physical Chemistry published new progress about ESR (electron spin resonance). 4956-05-2 belongs to class pyrimidines, and the molecular formula is C3H2BrN3O2, Computed Properties of 4956-05-2.
Referemce:
Pyrimidine | C4H4N2 – PubChem,
Pyrimidine – Wikipedia