Ion Binding Site Structure and the Role of Water in Alkaline Earth EDTA Complexes
Ion Binding Site Structure and the Role of Water in Alkaline Earth EDTA Complexes
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DOI：
10.1021/acs.jpclett.2c02391
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发表时间：
2022-09-06
影响因子：
5.7
通讯作者：
Weber, J. Mathias
中科院分区：
文献类型：
--
作者：
Foreman, Madison M.;Weber, J. Mathias
分子主体和离子客体之间的相互作用及其对化学环境的依赖性是具有挑战性的，从解决方案数据单独解开。乙二胺四乙酸（EDTA）螯合碱土金属dications在真空中的冷配合物的振动光谱编码这些配合物的结构特征和它们对结合离子的大小的依赖性。金属结合几何形状和形成结合口袋的羧酸基团的振动带的相对强度之间的相关性使我们能够表征水引起的分子几何形状的变化。这些结构标记物从裸离子到水加合物再到水溶液的演变说明了水对螯合剂中离子结合位点结构的作用。EDTA的结合袋在水溶液中打开，使结合的离子更接近结合位点的口，并导致离子暴露于化学环境的增加。
The interactions between molecular hosts and ionic guests and their dependence on the chemical environment are challenging to disentangle from solution data alone. The vibrational spectra of cold complexes of ethylenediaminetetraacetic acid (EDTA) chelating alkaline earth dications in vacuo encode structural characteristics of these complexes and their dependence on the size of the bound ion. The correlation between metal binding geometry and the relative intensities of vibrational bands of the carboxylate groups forming the binding pocket allows us to characterize water-induced changes in molecular geometry. The evolution of these structural markers from bare ions to water adducts to aqueous solution illustrates the role of water for the structure of ion binding sites in chelators. The binding pocket of EDTA opens up in aqueous solution, bringing the bound ion closer to the mouth of the binding site and leading to an increased exposure of the ion to the chemical environment.