Fig. 1: Amphoteric σ-hole [2]rotaxanes for cation or anion recognition.
From: Amphoteric chalcogen-bonding and halogen-bonding rotaxanes for anion or cation recognition
a, Anisotropically polarized halogen and chalcogen atoms possess localized electron-deficient σ-holes encompassed by electron-dense regions, endowing them with amphoteric character for anion binding or cation coordination (E = halogen or chalcogen; R, R′ = electron-withdrawing groups). b, The design of amphoteric tri- and tetradentate [2]rotaxanes incorporated with σ-hole donors inside the rotaxane cavities for convergent and multidentate cation or anion binding. c, Structures of the library of amphoteric tri- and tetradentate ChB/XB/HB σ-hole [2]rotaxanes studied in this work.
