Gas-Phase and Ionic Liquid Experimental and Computational Studies of Imidazole Acidity and Carbon Dioxide Capture.

The capture and storage of carbon dioxide are pressing environmental concerns. Nucleophilic capture by anions in ionic liquids, such as imidazolates, is a promising strategy. Herein, the gas-phase acidity of a series of imidazoles is examined both experimentally and computationally. The intrinsic acidity of these imidazoles has not heretofore been measured; these experimental data provide a benchmark for the computational values. The relationship between imidazole acidity and carbon dioxide capture is explored computationally, both in the gas phase and in ionic liquid. The improved understanding of imidazolate properties provided herein is important for the design and development of improved systems for carbon dioxide capture.