PDF(Pubmed)
Abstract：
Previous computational and experimental studies showed that charges located at the surroundings of hydrogen bonds can exert two opposite effects on them: rupture or strengthening of the hydrogen bond. This work aims to generalize the effect of charges in different hydrogen-bonded systems and to propose a coherent explanation of this effect. For these purposes, 19 systems with intra- and intermolecular hydrogen bonds were studied computationally with DFT. The FT-IR spectra of the systems were simulated, and two energy components of the hydrogen bond were studied separately to determine their variation upon the presence of a charge: charge transfer and molecular overlap. It was determined that either the breaking or strengthening of the hydrogen bond can be favored one over the other, for instance, depending on the heteroatom involved in the hydrogen bond. In addition, it is showed that the strengthening of the hydrogen bond by the presence of a charge is directly related to the decrease in charge transfer between the monomers, which is explained by an increase in molecular overlapping, suggesting a more covalent character of the interaction. The understanding of how hydrogen bonds are affected by charges is important, as it is a key towards a strategy to manipulate hydrogen bonds at convenience.
摘要：
先前的计算和实验研究表明，位于氢键周围的电荷会对它们产生两种相反的影响：氢键的破裂或增强。这项工作旨在概括不同氢键系统中电荷的影响，并对这种影响提出连贯的解释。出于这些目的,用DFT计算研究了19个具有分子内和分子间氢键的系统。模拟了系统的红外光谱,并分别研究了氢键的两个能量成分，以确定它们在电荷存在时的变化：电荷转移和分子重叠。已经确定，氢键的断裂或增强可以比另一个有利，例如,取决于氢键中涉及的杂原子。此外,结果表明，通过电荷的存在增强氢键与单体之间电荷转移的减少直接相关，这可以解释为分子重叠的增加，表明相互作用具有更共价的特征。了解氢键如何受到电荷的影响是很重要的，因为它是在方便时操纵氢键的策略的关键。
