Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, VU University Amsterdam, Amsterdam, The Netherlands.
Chemistry. 2011 Nov 4;17(45):12612-22. doi: 10.1002/chem.201102234. Epub 2011 Oct 13.
We show that the cooperative reinforcement between hydrogen bonds in guanine quartets is not caused by resonance-assisted hydrogen bonding (RAHB). This follows from extensive computational analyses of guanine quartets (G(4)) and xanthine quartets (X(4)) based on dispersion-corrected density functional theory (DFT-D). Our investigations cover the situation of quartets in the gas phase, in aqueous solution as well as in telomere-like stacks. A new mechanism for cooperativity between hydrogen bonds in guanine quartets emerges from our quantitative Kohn-Sham molecular orbital (MO) and corresponding energy decomposition analyses (EDA). Our analyses reveal that the intriguing cooperativity originates from the charge separation that goes with donor-acceptor orbital interactions in the σ-electron system, and not from the strengthening caused by resonance in the π-electron system. The cooperativity mechanism proposed here is argued to apply, beyond the present model systems, also to other hydrogen bonds that show cooperativity effects.
我们表明，鸟嘌呤四合子（G(4)）中氢键之间的协同增强并非由共振辅助氢键（RAHB）引起。这是基于对鸟嘌呤四合子（G(4)）和黄嘌呤四合子（X(4)）的扩展计算分析得出的，该分析基于色散校正的密度泛函理论（DFT-D）。我们的研究涵盖了气相、水溶液和端粒样堆积中四合子的情况。我们的定量 Kohn-Sham 分子轨道（MO）和相应的能量分解分析（EDA）揭示了鸟嘌呤四合子中氢键之间协同作用的新机制。我们的分析表明，这种有趣的协同作用源于与 σ 电子系统中的供体-受体轨道相互作用相伴的电荷分离，而不是来自于 π 电子系统中共振引起的加强。这里提出的协同作用机制被认为不仅适用于当前的模型体系，也适用于表现出协同作用的其他氢键。
