In biological systems, enzymes and transport proteins can bind anions in aqueous media solely by forming hydrogen bonds with charge-neutral motifs. Reproducing this functionality in synthetic systems presents challenges and incurs high costs, particularly when targeting strongly hydrated anions such as sulfate. Here we report a [2.2.2]urea cryptand (cage), synthesized in one pot, that selectively binds sulfate in a mixture of dimethyl sulfoxide and water and in water with affinities in the micromolar to millimolar range. The neutral cage bearing six urea groups donates 12 strong hydrogen bonds to encapsulate a sulfate anion, showing favourable enthalpy even in pure water. Sulfate binding can be further enhanced by using micelles to provide a low-polarity microenvironment. The cage finds utility in analysing divalent anions in water and beverage samples or in removing sulfate. The work demonstrates the achievability of robust and selective anion binding in water with minimal synthetic efforts, by using neutral NH hydrogen bonds akin to those found in biology.

在生物系统中，酶和转运蛋白可以仅通过与电荷中性基序形成氢键来结合水介质中的阴离子。在合成系统中重现这种功能面临着挑战并会产生高昂的成本，特别是在针对硫酸根等强水合阴离子时。在这里，我们报告了一种在一锅中合成的[2.2.2]脲穴状配体（笼），它选择性地结合二甲亚砜和水的混合物中的硫酸盐以及水中的硫酸盐，亲和力在微摩尔至毫摩尔范围内。带有六个脲基团的中性笼提供 12 个强氢键来封装硫酸根阴离子，即使在纯水中也显示出良好的焓。通过使用胶束提供低极性微环境可以进一步增强硫酸盐结合。该笼可用于分析水和饮料样品中的二价阴离子或去除硫酸盐。这项工作证明了通过使用类似于生物学中发现的中性 NH 氢键，可以以最少的合成努力实现水中牢固且选择性的阴离子结合。