Electron affinities of the DNA and RNA bases.
Electron affinities of the DNA and RNA bases.
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DOI：
10.1021/ja003814o
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发表时间：
2001-04
影响因子：
15
通讯作者：
S. Wesolowski;M. Leininger;P. N. Pentchev;H. Schaefer
中科院分区：
文献类型：
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作者：
S. Wesolowski;M. Leininger;P. N. Pentchev;H. Schaefer
DNA 和 RNA 碱基的绝热电子亲和力 (AEA) 是通过使用一系列具有双 zeta 加偏振加扩散 (DZP++) 基组的密度泛函来预测的，以努力将真实的 EA 括起来。尽管 AEA 在功能选择方面表现出适度的波动，但系统趋势表明共价尿嘧啶 (U) 和胸腺嘧啶 (T) 阴离子以 0.05-0.25 eV 结合，而腺嘌呤 (A) 阴离子明显未结合。对于三种最可靠的功能组合（BP86、B3LYP 和 BLYP），计算出的胞嘧啶 (C) 和鸟嘌呤 (G) 的 AEA 在较小的正值和负值之间振荡，并且尚不清楚是否结合了任一共价阴离子。 B3LYP/TZ2P++ 单点的 AEA 为 0.19 (U)、0.16 (T)、0.07 (G)、-0.02 (C) 和 -0.17 eV (A)。与从核碱基与水的复合物的光电子能谱数据推断的实验估计进行了有利的比较。然而，根据液相还原电位缩放的实验值高估了 AEA 高达 1.5 eV。由于尿嘧啶和胸腺嘧啶共价 EA 的能量范围接近其偶极结合对应物的能量范围，因此热力学稳定共价阴离子的制备和精确实验测量可能具有挑战性。
Adiabatic electron affinities (AEAs) for the DNA and RNA bases are predicted by using a range of density functionals with a double-zeta plus polarization plus diffuse (DZP++) basis set in an effort to bracket the true EAs. Although the AEAs exhibit moderate fluctuations with respect to the choice of functional, systematic trends show that the covalent uracil (U) and thymine (T) anions are bound by 0.05-0.25 eV while the adenine (A) anion is clearly unbound. The computed AEAs for cytosine (C) and guanine (G) oscillate between small positive and negative values for the three most reliable functional combinations (BP86, B3LYP, and BLYP), and it remains unclear if either covalent anion is bound. AEAs with B3LYP/TZ2P++ single points are 0.19 (U), 0.16 (T), 0.07 (G), -0.02 (C), and -0.17 eV (A). Favorable comparisons are made to experimental estimates extrapolated from photoelectron spectra data for the complexes of the nucleobases with water. However, experimental values scaled from liquid-phase reduction potentials are shown to overestimate the AEAs by as much as 1.5 eV. Because the uracil and thymine covalent EAs are in energy ranges near those of their dipole-bound counterparts, preparation and precise experimental measurement of the thermodynamically stable covalent anions may prove challenging.