Significant improvements in CO₂ capture by pyridine-containing anion-functionalized ionic liquids through multiple-site cooperative interactions.

A strategy for improving CO2 capture by new anion-functionalized ionic liquids (ILs) making use of multiple site cooperative interactions is reported. An extremely high capacity of up to 1.60 mol CO2 per mol IL and excellent reversibility were achieved by introducing a nitrogen-based interacting site on the phenolate and imidazolate anion. Quantum-chemical calculations, spectroscopic investigations, and calorimetric data demonstrated that multiple-site cooperative interactions between two kinds of interacting sites in the anion and CO2 resulted in superior CO2 capacities, which originated from the π-electron delocalization in the pyridine ring.