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Pillar[5]‐bis‐thiacrown: An Adaptive Tricyclic Host Selectively Recognizing an Organic Guest by Dimetalation
Author(s) -
Lee Eunji,
Ryu Hyunsoo,
Ju Huiyeong,
Kim Seulgi,
Lee JiEun,
Jung Jong Hwa,
Kuwahara Shunsuke,
Ikeda Mari,
Habata Yoichi,
Lee Shim Sung
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805275
Subject(s) - chemistry , metalation , tricyclic , molecule , pillar , stereochemistry , crystallography , two dimensional nuclear magnetic resonance spectroscopy , metal , organic chemistry , structural engineering , engineering
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 [Ag 2 L(NO 3 ) 2 ], with an Ag⋅⋅⋅Ag separation of 9.976 Å. Binding studies based on 1 H NMR including 2D NOESY and DOSY experiments towards α,ω‐dicyanoalkanes [CN(CH 2 ) n CN, n =2–6, shortly C2–C6] demonstrated that the dimetalated L, Ag 2 L 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.