Thermodynamic, Dynamic, and Structural Properties of Ionic Liquids Comprised of 1-Butyl-3-methylimidazolium Cation and Nitrate, Azide, or Dicyanamide Anions

Molecular dynamics simulations of ionic liquids (IL) comprised of 1-butyl-3-methylimidazolium [bmim] cation and nitrate [NO3], azide [N-3], or clicyanamide [N(CN)(2)] anions were conducted using the polarizable APPLE&P) force field. Comparison of thermodynamic properties such as densities, enthalpies of vaporization, and on binding energies as well as structural correlations obtained from simulations at atmospheric pressure and temperature range 298-393 K showed that IL with the N(CN)(2) anion shows significantly different characteristics as compared to ILs with the N-3 find NO3 anions. [bmim][N(CN)(2)] IL was found to have the lowest enthalpy of vaporization and the weakest ion ion structural correlation as compared to ILs with the other two ions. This trend was further manifested in dynamical properties characterized by self-diffusion coefficients and molecular rotational relaxation times, where IL with N(CN)(2) the anion showed the fastest dynamics as compared to other ILs. We also examine the dynamic correlations between the ions' translational and rotational motions as well as discuss the anisotropy of the latter.