We present a detailed study of specific ion effects, volcano plots and the law of matching solvent affinities by means of a conceptual density functional theory (DFT) approach. Our results highlight that specific ion effects and the corresponding implications on the solvation energy are mainly due to differences in the electric chemical potentials and chemical hardnesses of the ions and the solvent. Our approach can be further used to identify reliable criteria for the validity of the law of matching solvent affinities. Basic expressions are derived, which allow us to study the limiting conditions for this empirical observation with regard to matching chemical reactivity indices. Moreover, we show that chaotropic and kosmotropic concepts and their implications for the stability of ion pairs are directly related to a generalized strong and weak acids and bases (SWAB) principle for ions in solution, which is also applicable to rationalize the shape of volcano plots for different solvents. In contrast to previous assumptions, all empirical findings can be explained by the properties of local solvent‐ion complexes which dominate the specific global behavior of ion pairs in solution.

中文翻译：

---

对溶液中离子的特定离子效应和强弱酸碱法则的理论见解：从第一性原理推导匹配溶剂亲和力的定律。

我们通过概念性密度泛函理论（DFT）方法对特定离子效应，火山图和匹配溶剂亲和力定律进行了详细研究。我们的结果表明，特定的离子效应及其对溶剂化能的影响主要是由于离子和溶剂的电化学势和化学硬度不同所致。我们的方法可以进一步用于确定匹配溶剂亲和力定律有效性的可靠标准。推导了基本表达式，这使我们能够研究与匹配的化学反应性指数有关的这一经验观察的极限条件。此外，我们表明离液和正溶概念及其对离子对稳定性的影响与溶液中离子的广义强酸和弱酸和碱（SWAB）原理直接相关，这也适用于合理化不同火山图的形状溶剂。与以前的假设相反，所有的经验发现都可以由局部溶剂-离子配合物的特性来解释，该特性支配溶液中离子对的特定整体行为。