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首页> 外文期刊>Chemistry: A European journal >Charged versus Neutral Hydrogen-Bonded Complexes: Is There a Difference in the Nature of the Hydrogen Bonds?
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Charged versus Neutral Hydrogen-Bonded Complexes: Is There a Difference in the Nature of the Hydrogen Bonds?

机译：带电与中性氢键复合物：氢键的性质是否有所不同？

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摘要

A theoretical study on some carboxylic acid dimers formed by positively or negatively charged molecules has been carried out by using DFT methods. The resulting dimers possess either a charge of +2 or -2. In addition, the corresponding neutral complexes have also been considered. The electron density distribution described by the atoms in molecules and the natural bond orbital methods, as well as the electric field maps of the systems, have been analyzed and compared without finding significant differences between the neutral and ionic complexes. The interaction energy along the dissociation path of the charged dimers shows both a local minimum and a local maximum, defining a stability region between them. When this energetic profile is recalculated by removing the repulsion be-tween the charged groups, it resembles to those of the neutral molecules. Hence, the characteristics of the charged dimers are similar to those of the neutral ones: the addition of a repulsion term for the charged groups permits to retrieve the energetic profiles dependence with the distance in the charged system. The interacting quantum atom (IQA) method has been used to calculate the interaction energy terms, including the classic Coulombic term between the whole molecules and the corresponding of the carboxylic acid groups. The IQA results show repulsive electrostatic interactions when the whole molecules are considered in the ionic complexes, but attractive ones between the carboxylic groups in both neutral and ionic complexes.
机译：已经通过使用DFT方法对由带正电或带负电的分子形成的某些羧酸二聚体进行了理论研究。所得二聚体具有+2或-2的电荷。此外，还考虑了相应的中性配合物。分析和比较了分子中原子所描述的电子密度分布和自然键轨道方法以及系统的电场图，但未发现中性和离子络合物之间存在显着差异。沿着带电二聚体的解离路径的相互作用能显示出局部最小值和局部最大值，从而在它们之间定义了一个稳定区域。当通过消除带电基团之间的排斥力重新计算该高能分布时，它类似于中性分子的排斥。因此，带电二聚体的特性与中性二聚体的特性相似：为带电基团添加排斥项可以检索与带电系统中距离相关的高能分布。相互作用量子原子（IQA）方法已用于计算相互作用能项，包括整个分子与相应的羧酸基团之间的经典库仑项。当在离子络合物中考虑整个分子时，IQA结果显示出排斥性的静电相互作用，但在中性和离子络合物中的羧基之间都具有吸引作用。

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