Pillar[5]-bis-thiacrown: An Adaptive Tricyclic Host Selectively Recognizing an Organic Guest by Dimetalation |
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Authors: | Dr. Eunji Lee Hyunsoo Ryu Huiyeong Ju Seulgi Kim Dr. Ji-Eun Lee Prof. Jong Hwa Jung Prof. Shunsuke Kuwahara Prof. Mari Ikeda Prof. Yoichi Habata Prof. Shim Sung Lee |
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Affiliation: | 1. Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju, 52828 South Korea;2. Center for Research Facilities, Gyeongsang National University, Jinju, 52828 South Korea;3. Department of Chemistry, Toho University, 2-2-1 Miyama, Funabashi, Chiba, 274-8510 Japan;4. Department of Chemistry, Education Center, Faculty of Engineering, Chiba Institute of Technology, 2-1-1 Shibazono, Narashino, Chiba, 275-0023 Japan |
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Abstract: | Some biological receptors change their shapes and rigidity by metalation to recognize substrates precisely via adaptive guest binding process. Herein we present a semi-flexible tricyclic host molecule whose conformation is rigidified by dimetalation to uptake organic guests selectively. Considering two metal binding sites and an empty space between them, pillar[5]-bis-thiacrown (L) was synthesized. The tricyclic host L forms a disilver(I) complex [Ag2L(NO3)2], with an Ag⋅⋅⋅Ag separation of 9.976 Å. Binding studies based on 1H NMR including 2D NOESY and DOSY experiments towards α,ω-dicyanoalkanes [CN(CH2)nCN, n=2–6, shortly C2–C6] demonstrated that the dimetalated L, Ag2L preferentially recognizes C2 over other guests than that of free L. Furthermore, the dimetalated the host only uptakes C2 in the presence of other guests. Crystal structures support the idea that the space between two silver(I) centers plays a decisive role on the selective guest binding forming an Ag-C2-Ag@L arrangement via the length-selective recognition. This work demonstrates the chemical example of the adaptive guest binding and presents a new perspective on the metallosupramolecules of pillararenes. |
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Keywords: | host–guest systems macrocycles pillararenes silver supramolecular chemistry |
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