6898-94-8Relevant articles and documents
EPR and ENDOR Studies of 1H and 14N Hyperfine and Quadrupolar Couplings in Crystals of L-O-Serine Phosphate after X-Irradiation at 295 K
Sanderud, Audun,Sagstuen, Einar
, p. 9545 - 9555 (2007/10/03)
Single crystals of L-O-serine phosphate, (HOOC)CH(NH3(1+))CH2OPO3(1-)H, were X-irradiated at 295 K and studied using EPR, ENDOR, and FSE techniques.At this temperature, three carbon-centered radicals were identified.Radical I, the deamination product (HOOC)CH(1.)CH2OPO3(1-)H, is shown to have undergone a major molecular reorientation upon formation.Radical II is identified to be the product (HOOC)CH(NH3(1+))CH(1.)OPO3(1-)H.This species exhibits a nonplanar site for the lone electron density.This deviation from planarity is ascribed to electrostatic interaction between the lone electron orbital and lone pairs centered on the neighboring oxygen atom.Hyperfine interaction with the β-nitrogen of the amino group is observed.Both the 14N hyperfine and quadrupole coupling tensors are determined and the signs of the hyperfine coupling tensor principal values are deduced from interpretation of the quadrupole tensor employing the Townes-Dailey approach.The β14N isotropic interaction is well described by a Heller and McConnell type cos2θ rule.The results found in the present work, together with other recent observations, yield estimated values of the constants B0 = 1.0 MHz and B2 = 34.5 MHz.Radical III exhibits the structure (HOOC)CH(NH3(1+))CH2(1.), formed by scission of the phosphate-ester bond at the carbon side.No β14N coupling is observed for this radical due to a dihedral angle close to 90 deg.Possible mechanistic routes for the formation of these radicals are discussed in comparison with previously published data on serine and other alkyl phosphate derivatives.
Oxidation of Thiols and Disulphides with Ammoniumyl Radical-cation, +.NH3: an E.S.R. Investigation
Gilbert, Bruce C.,Marriott, Paul R.
, p. 191 - 197 (2007/10/02)
E.s.r. spectroscopy has been employed to demonstrate that the reaction of +.NH3 (from TiIII and +NH3OH) with thiols (RSH) proceeds via the initial formation of thiyl radicals (RS.); these react further to give disulphides as well as oxygen-containing radicals RSO. and RSO2., formed by a series of one-electron oxidation reactions, and both SO2-. and SO3-. (which arise via sulphur dioxide formed in the decomposition of RSO2.).Reaction with disulphides, which leads to the detection of sulphinyl radicals and disulphide-conjugated radicals, is thought to involve both radical-cations (RSSR+.) and ammoniumyl adducts .(N+H3)SR> whose further reactions have been described.
