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Chalcogen Bonding Macrocycles and [2]Rotaxanes for Anion Recognition

DOI: 10.1021/jacs.6b12745 DOI Help

Authors: Jason Y. C. Lim (University of Oxford) , Igor Marques (University of Aveiro) , Amber L. Thompson (University of Oxford) , Kirsten E. Christensen (University of Oxford) , Vitor Felix (University of Aveiro) , Paul D Beer (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: January 2017
Diamond Proposal Number(s): 13639

Abstract: Electron-deficient heavy chalcogen atoms contain Lewis acidic σ-holes which are able to form attractive supramolecular interactions, known as chalcogen bonding (ChB), with Lewis bases. However, their potential in solution-phase anion binding applications is only just beginning to be realized in simple acyclic systems. Herein, we explore the 5-(methylchalcogeno)-1,2,3-triazole (chalcogen = Se, Te) motif as a novel ChB donor for anion binding. Other than being chemically-robust enough to be in-corporated into macrocyclic structures, thereby significantly expanding the scope and complexity of ChB host systems, we also demonstrate, by 1H NMR and DFT calculations, that the chalcogen atoms oriented within the macrocycle cavity are able to chelate copper(I) endotopically. Exploiting this property, the first examples of mechanically-interlocked [2]rotaxanes containing ChB-donor groups are prepared via an active metal template strategy. Solution-phase 1H NMR and molecular modelling studies provide compelling evidence for the dominant influence of ChB in anion binding by these interlocked host systems. In addition, unprece-dented charge assisted ChB-mediated anion binding was also studied in aqueous solvent mixtures which revealed considerable differences in anion recognition behavior in comparison with chalcogen-free host analogues. Moreover, DFT calculations and Molecular Dynamics simulations in aqueous solvent mixtures indicate that the selectivity is determined by the different hydrophilic character of the anions allied to the hydration of the binding units in the presence of the anions. Exploiting the NMR-active nuclei of the ChB-donor chalcogen atoms, heteronuclear 77Se and 125Te NMR was used to directly study how anion recognition influences the local electronic environment of the chalcogen atoms in the mechanically bonded rotaxane binding sites in organic and aqueous solvent mixtures.

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 06/02/2017 09:22

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