Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam, The Netherlands.
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, The Netherlands.
Chemistry. 2017 Aug 1;23(43):10249-10253. doi: 10.1002/chem.201701821. Epub 2017 Jun 1.
Theoretical and experimental studies have elucidated the bonding mechanism in hydrogen bonds as an electrostatic interaction, which also exhibits considerable stabilization by charge transfer, polarization, and dispersion interactions. Therefore, these components have been used to rationalize the differences in strength of hydrogen-bonded systems. A completely new viewpoint is presented, in which the Pauli (steric) repulsion controls the mechanism of hydrogen bonding. Quantum chemical computations on the mismatched DNA base pairs CC and GG (C=cytosine, G=guanine) show that the enhanced stabilization and shorter distance of GG is determined entirely by the difference in the Pauli repulsion, which is significantly less repulsive for GG than for CC. This is the first time that evidence is presented for the Pauli repulsion as decisive factor in relative hydrogen-bond strengths and lengths.
理论和实验研究阐明了氢键中的成键机理为静电相互作用，其中电荷转移、极化和色散相互作用也表现出相当大的稳定作用。因此，这些成分已被用于合理化氢键系统强度的差异。本文提出了一个全新的观点，即 Pauli（位阻）排斥控制氢键的机制。对不匹配的 DNA 碱基对 CC 和 GG（C=胞嘧啶，G=鸟嘌呤）的量子化学计算表明，增强的 GG 稳定性和较短的距离完全取决于 Pauli 排斥的差异，GG 的 Pauli 排斥明显小于 CC。这是首次提出 Pauli 排斥是相对氢键强度和长度的决定性因素的证据。
