Oloff H, Sagstuen E
Int J Radiat Biol Relat Stud Phys Chem Med. 1981 Nov;40(5):493-505. doi: 10.1080/09553008114551471.
Single crystals of the 5-halogen substituted uracil derivative 1-methyl-5-bromouracil have been irradiated at 77 and 295 K and studied by electron spin resonance spectroscopy. At 295 K a hydrogen abstraction radical (I) from the methyl group was observed, together with a modified 5-yl radical (II). The latter species seem to be formed by addition of a non-interacting residue (probably CH3) to C6. At 77 K, radical I is observed together with two bromine-centered species. One of these (III) exhibits only bromine hyperfine interaction (maximum splitting of 515 G) and is assigned to a complexed cation radical. The third 77 K resonance could be due to a beta-bromine radical R'-C5HBr-C6H-R'. A computer program able to calculate powder spectra of radicals with dominant halogen interaction is described. The results are discussed in relation to radiation damage processes in the isomorphous crystals of 1-methylthymine.
5-卤素取代的尿嘧啶衍生物1-甲基-5-溴尿嘧啶的单晶在77 K和295 K下进行了辐照，并通过电子自旋共振光谱进行了研究。在295 K时，观察到来自甲基的氢提取自由基（I）以及一个修饰的5-基自由基（II）。后一种物种似乎是由一个非相互作用残基（可能是CH3）加成到C6上形成的。在77 K时，观察到自由基I以及两种以溴为中心的物种。其中一种（III）仅表现出溴超精细相互作用（最大分裂为515 G），并被指定为复合阳离子自由基。第三个77 K共振可能归因于β-溴自由基R'-C5HBr-C6H-R'。描述了一个能够计算具有主要卤素相互作用的自由基粉末光谱的计算机程序。结合1-甲基胸腺嘧啶同构晶体中的辐射损伤过程对结果进行了讨论。
