Mariscal Alexander, Sagal Luzelena, Doan Carson, Zhai Canjia, Liu Dexin, Wojtas Lukasz, Liu Wenqi
Department of Chemistry, University of South Florida, 4202 E. Fowler Ave, Tampa, Florida, 33620, USA.
Chemistry. 2025 Jun 23;31(35):e202501400. doi: 10.1002/chem.202501400. Epub 2025 May 15.
Achieving selective molecular recognition of hydrophilic anions in water remains a formidable challenge due to the competitive nature of water and the high hydration energies of target anions such as sulfate. Here, we report the design, synthesis, and characterization of a simple dicationic tetralactam macrocycle (BPTL⁺·2Cl⁻) capable of binding highly hydrated anions in water via charge-assisted hydrogen bonding. Structural, spectroscopic, thermodynamic, and computational studies reveal that BPTL⁺ exhibits a strong binding affinity for sulfate (K = 2892 M⁻¹), driven primarily by entropic gain from water release and reinforced by electrostatic and hydrogen bonding interactions. Single-crystal X-ray diffraction and DFT-optimized structures confirm the formation of directional [N─H•••O] and [C─H•••O] hydrogen bonds. Comparative studies with a control macrocycle (6Na•HCTL) that has a charge-neutral binding cavity underscore the essential role of cationic charge in overcoming desolvation enthalpic penalties. The receptor displays anti-Hofmeister selectivity, preferentially binding more hydrophilic anions. This work provides fundamental insights into the mechanisms of anion recognition in water. It establishes charge-assisted hydrogen bonding as a powerful strategy for developing next-generation receptors for sensing, separation, sequestration, transport, and catalysis in aqueous environments.
由于水的竞争性以及诸如硫酸根等目标阴离子的高水合能，在水中实现对亲水性阴离子的选择性分子识别仍然是一项艰巨的挑战。在此，我们报道了一种简单的双阳离子四内酰胺大环化合物（BPTL⁺·2Cl⁻）的设计、合成及表征，该化合物能够通过电荷辅助氢键在水中结合高度水合的阴离子。结构、光谱、热力学和计算研究表明，BPTL⁺对硫酸根表现出很强的结合亲和力（K = 2892 M⁻¹），这主要由水释放带来的熵增驱动，并通过静电和氢键相互作用得到加强。单晶X射线衍射和DFT优化结构证实了定向[N─H•••O]和[C─H•••O]氢键的形成。与具有电荷中性结合腔的对照大环化合物（6Na•HCTL）的对比研究强调了阳离子电荷在克服去溶剂化焓罚方面的关键作用。该受体表现出反霍夫迈斯特选择性，优先结合更亲水性的阴离子。这项工作为水中阴离子识别机制提供了基本见解。它确立了电荷辅助氢键作为一种强大策略，用于开发在水性环境中用于传感、分离、螯合、运输和催化的下一代受体。
