Tuning cation–anion interactions in ionic liquids by changing the conformational flexibility of the cation

Abstract

Cation–anion interactions can be tuned via the degree of cation constraint. X-ray Photoelectron Spectroscopy (XPS) experiments reveal that anion–cation based interactions may be enhanced by introducing conformational restriction into the substituent chains of quaternary ammonium cations. A larger degree of charge-transfer was observed for the constrained [C₈C₁Pyrr]⁺ cation relative to the [N_6,6,6,14]⁺ cation.