Computational Study of the Proton Affinity, 1 H NMR Chemical Shifts, and Thermophysical Properties of Imidazole Derivatives

There has been increasing interest in developing new materials for CO₂ capture. One of the approaches is to synthesize polymer membrane using imidazole derivatives as the monomer. These imidazole derivatives are able to react with aqueous CO₂ to form bicarbonate anions, thus enabling facilitated transport of CO₂ through the membrane. In order to better understand the chemical and thermophysical properties of imidazole derivatives, we have employed quantum mechanics and molecular dynamics methods to calculate the proton affinities, ¹H NMR chemical shifts, and absorption properties of a variety of imidazole derivatives. From our simulations, a quantitative characterization of the effect of various exocyclic substituents on the proton affinity of imidazole was achieved. In particular, we find that electron-donating groups are able to increase the proton affinity of imidazole. In addition, the calculated ¹H NMR chemical shift and thermophysical properties are in excellent with experiment. These results will be helpful for future experimental design of new materials to be used for CO₂ capture.