Studies of cationic radicals in .gamma.-irradiated single crystals of .alpha.-aminoisobutyric acid and related .alpha.-amino acids by electron spin resonance and SCF MO INDO calculation
Studies of cationic radicals in .gamma.-irradiated single crystals of .alpha.-aminoisobutyric acid and related .alpha.-amino acids by electron spin resonance and SCF MO INDO calculation
复制标题
通过电子自旋共振和SCF MO INDO计算研究γ-辐照的α-氨基异丁酸和相关α-氨基酸单晶中的阳离子自由基
DOI：
10.1021/j100532a018
复制
发表时间：
1977
期刊：
影响因子：
--
通讯作者：
A. Minegishi
中科院分区：
文献类型：
--
作者：
A. Minegishi
通过 X 和 Q 波段 ESR（包括光漂白测量），在 77/sup 0/K 下照射的 ..cap α..-氨基异丁酸 ..γ.. 单晶的阳离子自由基被鉴定为去质子化阳离子自由基 NH/sub 2/C(CH/sub 3/)/sub 2/COO。 g 张量的特征值确定为 2.0052、2.0021 和 2.0013。 g/sub max/(2.0052)的特征向量垂直于分子平面，不成对电子轨道的密度轴，即g/sub int/(2.0021)的特征向量平行于分子轴(Y轴)。 g/sub min/(2.0013) 的特征向量位于分子平面上并垂直于分子轴。除了甲基质子的超精细耦合之外，还估计了 N 的超精细耦合，它与分子轴轴对称，并且 N 上的不成对电子密度对于 2p/sub y/ 为 0.1，对于 2s 为 0.01。这些特征得到了 SCF MO INDO 计算的支持。去质子化阳离子自由基和前者的前体氢键阳离子自由基表现出类似的由2p/sub y/s骨架原子组成的不成对电子轨道，但去质子化阳离子自由基的g各向异性比阳离子自由基小。 L-..capmore » α..-丙氨酸和甘氨酸的阳离子自由基也进行了类似的研究，并分配给如上所述的去质子化阳离子自由基。 « less
The cationic radical of the single crystal of ..cap alpha..-aminoisobutyric acid ..gamma.. irradiated at 77/sup 0/K was identified as the deprotonated cation radical, NH/sub 2/C(CH/sub 3/)/sub 2/COO, by X- and Q-band ESR including photobleaching measurement. The eigenvalues of the g tensor were determined to be 2.0052, 2.0021, and 2.0013. The eigenvector of g/sub max/(2.0052) is perpendicular to the molecular plane and the density axis of the unpaired electron orbital, i.e., the eigenvector of g/sub int/(2.0021), is parallel to the molecular axis (Y axis). The eigenvector of g/sub min/(2.0013) is on the molecular plane and perpendicular to the molecular axis. In addition to the hyperfine coupling by methyl protons, the hyperfine coupling by N was estimated, which is axially symmetric to the molecular axis and gives the unpaired electron density on N as 0.1 for 2p/sub y/ and 0.01 for 2s. These features were supported by SCF MO INDO calculations. The deprotonated cation radical and the hydrogen bonded cation radical, the precursor of the former, show similar unpaired electron orbitals consisting of 2p/sub y/s of the skeleton atoms, but the g anisotropy of the deprotonated cation radical is smaller compared with that of the cation radical. The cationic radicals of L-..capmore » alpha..-alanine and glycine were also similarly investigated and assigned to the deprotonated cation radicals as mentioned above.« less