Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland.
J Phys Chem B. 2010 Sep 2;114(34):11353-62. doi: 10.1021/jp104668h.
The photoelectron spectrum for (1-methylthymine)-(9-methyladenine)...(formic acid) (1MT-9MA...FA) anions with the maximum at ca. 1.87 eV was recorded with 2.54 eV photons and interpreted through the quantum-chemical modeling carried out at the B3LYP/6-31+G(d,p) level. The relative free energies of the anions and their calculated vertical detachment energies suggest that only seven anionic structures contribute to the observed PES signal. We demonstrate that electron binding to the (1MT-9MA...FA) complex can trigger intermolecular proton transfer from formic acid, leading to the strong stabilization of the resulting radical anion. The SOMO distribution indicates that an excess electron may localize not only on the pyrimidine but also on the purine moiety. The biological context of DNA-environment interactions concerning the formation of single-strand breaks induced by excess electrons has been briefly discussed.
用 2.54eV 的光子记录了最大峰约为 1.87eV 的（1-甲基胸腺嘧啶）-（9-甲基腺嘌呤）…（甲酸）（1MT-9MA…FA）阴离子的光电子能谱，并通过在 B3LYP/6-31+G（d，p）水平上进行的量子化学建模进行了解释。阴离子的相对自由能及其计算的垂直离解能表明，只有七种阴离子结构对观察到的 PES 信号有贡献。我们证明，电子与（1MT-9MA…FA）复合物的结合可以触发甲酸的分子间质子转移，导致生成的自由基阴离子的强烈稳定化。SOMO 分布表明，过剩电子不仅可以定域在嘧啶上，也可以定域在嘌呤部分。简要讨论了与过量电子诱导的单链断裂形成有关的 DNA-环境相互作用的生物学背景。
