Anti‐Hofmeister Anion Selectivity via a Mechanical Bond Effect in Neutral Halogen‐Bonding [2]Rotaxanes. (17th November 2022)

• Record Type: Journal Article
• Authors: Docker, Andrew; Tse, Yuen Cheong; Tay, Hui Min; Taylor, Andrew J.; Zhang, Zongyao; Beer, Paul D.
• Is Part Of: Angewandte Chemie. Volume 134:Number 50(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-17
• Subjects: Anion Recognition -- Anti-Hofmeister Bias -- Halogen Bonding (XB) -- Mechanically Interlocked Molecules -- Rotaxanes; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202214523
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Exceptionally strong halogen bonding (XB) donor‐chloride interactions are exploited for the chloride anion template synthesis of neutral XB [2]rotaxane host systems which contain perfluoroaryl‐functionalised axle components, including a remarkably potent novel 4, 6‐dinitro‐1, 3‐bis‐iodotriazole motif. Halide anion recognition properties in aqueous‐organic media, determined via extensive 1 H NMR halide anion titration experiments, reveal the rotaxane host systems exhibit dramatically enhanced affinities for hydrophilic Cl − and Br −, but conversely diminished affinities for hydrophobic I −, relative to their non‐interlocked axle counterparts. Crucially, this mechanical bond effect induces a binding selectivity which directly opposes Hofmeister bias. Free‐energy analysis of this mechanical bond enhancement demonstrates anion recognition by neutral XB interlocked host systems as a rare and general strategy to engineer anti‐Hofmeister bias anion selectivity in synthetic receptor design. Abstract : Neutral XB [2]rotaxanes containing remarkably potent XB axle components including a novel 4, 6‐dinitro‐1, 3‐bis‐iodotriazole motif are constructed via a discrete chloride anion template directed synthesis. Quantitative 1 H NMR halide anion titration studies in competitive aqueous‐organic solvent mixtures reveal the XB [2]rotaxanes display pronounced anti‐Hofmeister halide anion recognition selectivity for chloride over iodide.