Gregory Kasimir P, Wanless Erica J, Webber Grant B, Craig Vincent S J, Page Alister J
Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle Callaghan New South Wales 2308 Australia
School of Engineering, The University of Newcastle Callaghan New South Wales 2308 Australia.
Chem Sci. 2021 Oct 16;12(45):15007-15015. doi: 10.1039/d1sc03568a. eCollection 2021 Nov 24.
Life as we know it is dependent upon water, or more specifically salty water. Without dissolved ions, the interactions between biological molecules are insufficiently complex to support life. This complexity is intimately tied to the variation in properties induced by the presence of different ions. These specific ion effects, widely known as Hofmeister effects, have been known for more than 100 years. They are ubiquitous throughout the chemical, biological and physical sciences. The origin of these effects and their relative strengths is still hotly debated. Here we reconsider the origins of specific ion effects through the lens of Coulomb interactions and establish a foundation for anion effects in aqueous and non-aqueous environments. We show that, for anions, the Hofmeister series can be explained and quantified by consideration of site-specific electrostatic interactions. This can simply be approximated by the radial charge density of the anion, which we have calculated for commonly reported ions. This broadly quantifies previously unpredictable specific ion effects, including those known to influence solution properties, virus activities and reaction rates. Furthermore, in non-aqueous solvents, the relative magnitude of the anion series is dependent on the Lewis acidity of the solvent, as measured by the Gutmann Acceptor Number. Analogous SIEs for cations bear limited correlation with their radial charge density, highlighting a fundamental asymmetry in the origins of specific ion effects for anions and cations, due to competing non-Coulombic phenomena.
我们所知的生命依赖于水，或者更具体地说是盐水。没有溶解的离子，生物分子之间的相互作用就不够复杂，无法支持生命。这种复杂性与不同离子的存在所引起的性质变化密切相关。这些特定的离子效应，广为人知的霍夫迈斯特效应，已经被人们知晓了100多年。它们在化学、生物学和物理科学中无处不在。这些效应的起源及其相对强度仍在激烈争论中。在这里，我们通过库仑相互作用的视角重新审视特定离子效应的起源，并为水性和非水性环境中的阴离子效应奠定基础。我们表明，对于阴离子，霍夫迈斯特序列可以通过考虑位点特异性静电相互作用来解释和量化。这可以简单地通过阴离子的径向电荷密度来近似，我们已经计算了常见报道离子的径向电荷密度。这广泛地量化了以前无法预测的特定离子效应，包括那些已知会影响溶液性质、病毒活性和反应速率的效应。此外，在非水溶剂中，阴离子序列的相对大小取决于溶剂的路易斯酸度，通过古特曼受体数来衡量。阳离子的类似特定离子效应与其径向电荷密度的相关性有限，这突出了由于竞争的非库仑现象，阴离子和阳离子特定离子效应起源的基本不对称性。
