Giribet Claudia G
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Buenos Aires 1428, Argentina.
CONICET, Universidad de Buenos Aires, Instituto de Física de Buenos Aires (IFIBA), Buenos Aires 1428, Argentina.
J Phys Chem A. 2024 Sep 12;128(36):7568-7580. doi: 10.1021/acs.jpca.4c03817. Epub 2024 Aug 27.
The IPPP-CLOPPA method is applied to investigate the feasibility of the C-H···O moiety as a third hydrogen bond in the adenine-thymine base pair, and the role of this intermolecular contact in its stability. For this purpose, an analysis of the interaction energy and the potential energy of the protons of the "conventional" intermolecular hydrogen bonds and the "unconventional" C-H···O contact is performed, in order to assess how much they contribute to the intermolecular stabilization energy of the base pair. On the same grounds, this study is complemented by the analysis of the molecular electric dipolar polarizability of the hydrogen bond moieties, in order to determine the information that this property can give about the electronic mechanisms that affect the stabilization of the hydrogen bonds, the influence of the π system on each one, and the cooperativity effects among them. The results obtained seem to confirm that the C-H···O moiety contributes to the stability of the adenine-thymine pair almost as much as the "conventional" hydrogen bonds do. Besides, this stabilization effect is strengthened by cooperativity between hydrogen bonds and, particularly and mostly, with the π system.
应用IPPP - CLOPPA方法研究C - H···O部分作为腺嘌呤 - 胸腺嘧啶碱基对中第三个氢键的可行性，以及这种分子间接触在其稳定性中的作用。为此，对“常规”分子间氢键和“非常规”C - H···O接触的质子的相互作用能和势能进行分析，以评估它们对碱基对分子间稳定能的贡献程度。基于同样的理由，本研究通过对氢键部分的分子电偶极极化率的分析加以补充，以确定该性质能够提供的有关影响氢键稳定性的电子机制、π体系对每个氢键的影响以及它们之间的协同效应的信息。所得结果似乎证实，C - H···O部分对腺嘌呤 - 胸腺嘧啶碱基对稳定性的贡献几乎与“常规”氢键相同。此外，氢键之间的协同作用，特别是与π体系的协同作用，增强了这种稳定效应。
