Complex of the host, which bears four amide groups and two crown ethers, and Cs+, recognizes chloride and bromide anions much more strongly than the free host, because the host captures one Cs+ ion with the two crown rings in a face-to-face fashion to cyclize the host, and the preorganization of the amide protons forms the good binding site for the anions.
带有四个酰胺基团和两个
冠醚的宿主与 Cs+ 复合物对
氯化物和
溴化物阴离子的识别能力比游离宿主强得多,这是因为宿主以面对面的方式用两个冠环捕获一个 Cs+ 离子,使宿主环化,酰胺质子的预组织形成了阴离子的良好结合点。