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Cooperative Silver Ion-Pair Recognition by Peralkylated Pillararenes
- Hua, Bin, Shao, Li, Zhang, Zhihua, Liu, Jiyong, Huang, Feihe
- Journal of the American Chemical Society 2019 v.141 no.38 pp. 15008-15012
- X-ray diffraction, absorbents, aromatic hydrocarbons, hydrogen bonding, salts, silver
- Ion-pair recognition of metal salts by pillararenes has never been reported. This limits the further development and applications of pillararene supramolecular chemistry. Herein we report the first examples of pillararene-based metal ion-pair recognition. They are host–guest complexes between three peralkylated pillararenes and the silver salt CF₃COOAg. Single crystal X-ray analysis shows that CF₃COOAg forms a unique dinuclear silver structure that penetrates into the pillararene cavity in these complexes. Besides the silver-π interactions, multiple C–H···O and C–H···F hydrogen bonds between the counterion and the pillararene host also contribute to stabilizing and maintaining the host–guest structures. Moreover, benefiting from the silver ion-pair recognition, perethylated pillararene EtP5 can be used as a solid absorbent to capture CF₃COOAg from solution efficiently, showing a potential application in precious metal extraction and recycling.