Photoinduced C-I bond homolysis of 5-iodouracil: A singlet predissociation pathway
文献类型：期刊论文
| 作者 | Dai, Xiaojuan1,2; Song, Di1; Liu, Kunhui1,3; Su, Hongmei1,2,3 |
| 刊名 | JOURNAL OF CHEMICAL PHYSICS
 |
| 出版日期 | 2017-01-14 |
| 卷号 | 146期号:2 |
| 英文摘要 | 5-Iodouracil (5-IU) can be integrated into DNA and acts as a UV sensitive chromophore suitable for probing DNA structure and DNA-protein interactions based on the photochemical reactions of 5-IU. Here, we perform joint studies of time-resolved Fourier transform infrared (TR-FTIR) spectroscopy and ab initio calculations to examine the state-specific photochemical reaction mechanisms of the 5-IU. The fact that uracil (U) is observed in TR-FTIR spectra after 266 nm irradiation of 5-IU in acetonitrile and ascribed to the product of hydrogen abstraction by the uracil-5-yl radical (U center dot) provides experimental evidence for the C-I bond homolysis of 5-IU. The excited state potential energy curves are calculated with the complete active space second-order perturbation//complete active space self-consistent field method, from which a singlet predissociation mechanism is elucidated. It is shown that the initially populated 1(pi pi*) state crosses with the repulsive 1(pi sigma*) or (1)(n(I)sigma*) state, through which 5-IU undergoes dissociation to the fragments of (U center dot) radical and iodine atom. In addition, the possibility of intersystem crossing (ISC) is evaluated based on the calculated vertical excitation energies. Although a probable ISC from 1(pi pi*) state to (3)(n(O)pi*) and then to the lowest triplet (3)(pi pi*) could occur in principal, there is little possibility for the excited state populations bifurcating to triplet manifold, given that the singlet state predissociation follows repulsive potential and should occur within dozens to hundreds of femtoseconds. Such low population of triplet states means that the contribution of triplet state to photoreactions of 5-IU should be quite minor. These results demonstrate clearly a physical picture of C-I bond homolysis of 5-IU and provide mechanistic illuminations to the interesting applications of 5-IU as photoprobes and in radiotherapy of cancer. |
| 语种 | 英语 |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/38206]  |
| 专题 | 化学研究所_光化学实验室 |
| 作者单位 | 1.Chinese Acad Sci, BNLMS, Inst Chem, Beijing 100190, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Beijing Normal Univ, Coll Chem, Beijing 100875, Peoples R China |
| 推荐引用方式 GB/T 7714 | Dai, Xiaojuan,Song, Di,Liu, Kunhui,et al. Photoinduced C-I bond homolysis of 5-iodouracil: A singlet predissociation pathway[J]. JOURNAL OF CHEMICAL PHYSICS,2017,146(2). |
| APA | Dai, Xiaojuan,Song, Di,Liu, Kunhui,&Su, Hongmei.(2017).Photoinduced C-I bond homolysis of 5-iodouracil: A singlet predissociation pathway.JOURNAL OF CHEMICAL PHYSICS,146(2). |
| MLA | Dai, Xiaojuan,et al."Photoinduced C-I bond homolysis of 5-iodouracil: A singlet predissociation pathway".JOURNAL OF CHEMICAL PHYSICS 146.2(2017). |
入库方式： OAI收割
来源：化学研究所
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