Chemistry Research Laboratory, Department of Chemistry , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K.
Department of Chemistry, CICECO - Aveiro Institute of Materials , University of Aveiro , 3810-193 Aveiro , Portugal.
J Am Chem Soc. 2019 Mar 6;141(9):4119-4129. doi: 10.1021/jacs.9b00148. Epub 2019 Feb 19.
A novel strategy for the recognition of anions in water using charge-neutral σ-hole halogen and chalcogen bonding acyclic hosts is demonstrated for the first time. Exploiting the intrinsic hydrophobicity of halogen and chalcogen bond donor atoms integrated into a foldamer structural molecular framework containing hydrophilic functionalities, a series of water-soluble receptors was constructed for an anion recognition investigation. Isothermal titration calorimetry (ITC) binding studies with a range of anions revealed the receptors to display very strong and selective binding of large, weakly hydrated anions such as I and ReO. This is achieved through the formation of 2:1 host-guest stoichiometric complex assemblies, resulting in an encapsulated anion stabilized by cooperative, multidentate, convergent σ-hole donors, as shown by molecular dynamics simulations carried out in water. Importantly, the combination of multiple σ-hole-anion interactions and hydrophobic collapse results in I affinities in water that exceed all known σ-hole receptors, including cationic systems (β up to 1.68 × 10 M). Furthermore, the anion binding affinities and selectivity trends of the first example of an all-chalcogen bonding anion receptor in pure water are compared with halogen bonding and hydrogen bonding receptor analogues. These results further advance and establish halogen and chalcogen bond donor functions as new tools for overcoming the challenging goal of anion recognition in pure water.
首次展示了一种使用电荷中性σ-hole 卤素和硫属键非环主体识别水中阴离子的新策略。利用整合到含有亲水官能团的折叠体结构分子框架中的卤素和硫属键供体原子的固有疏水性，构建了一系列水溶性受体以进行阴离子识别研究。与一系列阴离子的等温滴定量热法（ITC）结合研究表明，这些受体对大的、水合较弱的阴离子（如 I 和 ReO ）具有很强的选择性结合。这是通过形成 2:1 主客体计量比配合物组装来实现的，这导致由协同的、多齿的、会聚的σ-hole 供体稳定的包封阴离子，如在水中进行的分子动力学模拟所示。重要的是，多个σ-hole-阴离子相互作用和疏水塌陷的组合导致水中 I 的亲和力超过所有已知的σ-hole 受体，包括阳离子体系（β高达 1.68×10^M）。此外，还比较了首例纯水中全硫属键阴离子受体的阴离子结合亲和力和选择性趋势与卤键和氢键受体类似物。这些结果进一步推进并确立了卤素和硫属键供体功能作为在纯水中识别阴离子的新工具。
