Tritopic ion‐pair receptors can bind bivalent salts in solution; yet, these salts have a tendency to form ion‐pairs even in the absence of receptors. The extent to which such receptors can enhance ion pairing has however remained elusive. Here, we study ion pairing of M²⁺ (Ba²⁺, Sr²⁺) and X⁻ (I⁻, ClO₄⁻) in acetonitrile with and without a dichlorooxacalix[2]arene[2]triazine‐related receptor containing a pentaethylene‐glycol moiety. We find marked ion association already in receptor‐free solutions. When present, most of the MX⁺ ion‐pairs are bound to the receptor and the overall degree of ion association is enhanced due to coordinative, hydrogen‐bonding, and anion‐π interactions. The receptor shows higher selectivity for iodides but also stabilizes perchlorates, despite the latter are often considered as weakly coordinating anions. Our results show that ion‐pair binding is strongly correlated to ion pairing in these solutions, thereby highlighting the importance of taking ion association in organic solvents into account.

中文翻译：

---

溶液中的三对离子对增强Sr（II）和Ba（II）盐的离子配对。

三位离子对受体可以结合溶液中的二价盐。然而，即使没有受体，这些盐也容易形成离子对。然而，这种受体可以增强离子配对的程度仍然难以捉摸。在这里，我们研究M的离子配对²⁺（BA ²⁺，锶²⁺）和X ^-（I ^-，CLO ₄ ^- ）的乙腈具有和不具有dichlorooxacalix [2]芳烃[2]三嗪相关受体含有五亚乙基二醇部分。我们发现无受体溶液中已经存在明显的离子缔合。如果有，大多数MX ⁺离子对与受体结合，并且由于配位，氢键和阴离子-π相互作用而增强了离子缔合的整体程度。该受体显示出对碘化物的更高选择性，而且还稳定了高氯酸盐，尽管后者通常被认为是弱配位阴离子。我们的结果表明，离子对结合与这些溶液中的离子对密切相关，从而突出了考虑有机溶剂中离子缔合的重要性。