title: Increased halide recognition strength by enhanced intercomponent preorganisation in triazolium containing [2]rotaxanes.
abstract: Three triazolium-based [2]rotaxanes containing different sized axle and macrocycle components were synthesised in good yields (40-57%) through chloride anion templation. The anion recognition properties of the interlocked receptor systems were investigated using (1)H NMR titration experiments: all three rotaxanes display impressive selectivities for halide anions over the more basic oxoanion acetate. The rotaxanes incorporating shorter, more rigid axle components with aryl-substituted triazolium groups display substantially higher anion binding affinities than those with longer, bis-alkyl-substituted heterocycles, which is attributed to the increased intercomponent preorganisation afforded by the smaller axle component. Computational DFT and molecular dynamics simulations composed of unconstrained and umbrella sampling simulations corroborate the experimental observations.
authors.affiliation: Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA (UK).
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: White
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Costa
authors.forename: Sílvia
authors.initials: S
authors.lastname: Carvalho
authors.forename: Vítor
authors.initials: V
authors.lastname: Félix
authors.forename: Paul D
authors.initials: PD
authors.lastname: Beer
mesh_terms: D000838:Anions / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D043862:Rotaxanes / Q000737:chemistry*
chemical_list: D000838:Anions; D043862:Rotaxanes
keywords: anions; molecular dynamics; preorganisation; rotaxanes; triazolium